This is by far the best review of chinese transmiters in RUclips. I was concerned about spureous emisions and harmónica and you solved all my doubts. I apreciate your help.
It doesn't work like that unfortunately. The chip would have to be programmed to support it. I'm not even sure if it has full RDS. I think only partially. When you use stereotool, you need to make sure RDS and MPX are disabled. Everything else like AGC will work fine.
@@MiiMaker Cause they probably bypassed the stereo gen portion of the chip and sent it right into the VCO. I think it's only possible with that chip. On other chips like the quintic chips, they are all digital and integrated, so you can not do that. I guess you could see that as one of the downsides to those chips. I never used RDS cause I don't like the way it spreads out the signal even more. I like it to stay as narrow as possible.
You know I've bought 5 of these on Ali Express, they keep saying "DELIVERED" always to someone with a fake name, like Chad Chaddington (I live in Australia so that's not even a remotely feasible name here) and never actually arrive. Idk if they're just not prepared to sell them as cheap as they are going for or what, but they keep refusing to send what I buy.
I've tried the shit QN8027 in the Little 1mw ebay tx module, and found there was a few spurs at +-12Mhz on each side of the carrier, but is nearly -35 and -40 dbc not 25 -15dbc like yours. I added a 1Watt rf booster amp on it, but used a tuned ring and stub ant it has a narrow bandwidth and the spurs end up -60dbc down, I tested the band splatter with a fm radio just meters from the transmitter and yes its like faint second station appearing across the band, but its so weak there is no way it will interfere with another broadcaster. The sound is good, you can actually plug the thing in and it powered via the usb socket and it comes up as a sound card CD002 you send digital audio directly to it. It sounds is surprisingly good.
I got the one at the lower left @15:46. I got it from "SZHQ Eelectronic [sic] Store" through AliExpress for about $30 including shipping to the US. It came without any documentation. Here's what I figured out: The DC input is specified at 12 volts at 1.0 Amp. It does not come with a power supply, so I used one I had on hand: 12 V up to 3 amps. The audio input on the heatsink side is apparently the stereo "line level" input. I presume the other is "mic level"; its tip has 5 volts on it (for a condenser mic?). On startup, a momentary message appears in Chinese. Google translate said "This kit is only for sale abroad. It is strictly forbidden for sale or use in China. Violators shall be liable for all legal responsibility!!!" There is a sticker on the heatsink that says the same thing. I guess the Great Firewall can't stop FM radio. After the Chinese warning, a settings screen appears. There are a total of three parameters that can be adjusted: "FRE", "VOL," and "PO" (frequency, volume [modulation level], and power). There are three buttons along the right side of the display; let's call them UP, MENU, and DOWN. To adjust the parameters: press and hold MENU for 4 seconds. The FRE item is highlighted, and the UP and DOWN buttons will adjust the frequency in 0.1 MHz steps. Once FRE is highlighted, pressing MENU highlights each other parameter in turn. Changes take effect immediately. VOL has a range of "0" to "30," and came set at 30. At 30, only tiny hint of audio was heard. It wasn't like it was very quiet, but more like only the loudest parts were punching through. Only by LOWERING the VOL setting to about 19 could audio be heard. It was like there was a DC bias on the audio and the VOL setting was amplifying and pushing the whole signal into clipping. This was with the line level input; I did not try the mic input. I suppose the mic and line level signals are summed at some fixed ratio? And the VOL adjust affects the sum? The "PO" power setting goes from "0" to "300". I used a Surecom SW-102 meter (ruclips.net/video/3GbvHtnK-eI/видео.html) into a dummy load to measure the power. The SW-102 is designed for 125 - 525 MHz and I had set the transmitter to 106.5 MHz, which may explain why it only read "1.53" watts at setting "300". Or maybe it really only puts out less than 2 watts? Lowering the PO setting lowered the power as low as "0.071" watt at setting "100". Below setting "67" the power jumped up to full power again! Strange. After running about an hour at max power, the heatsink was 21 deg C above ambient. It sound like there is pre-emphasis, but there is no pre-emphasis adjustment; I don't know what it is set to (50 or 75 uS?). There is an SD card slot, but no menu item refers to it. Perhaps plugging an SD card with mp3 files will cause them to be played? And summed to the mic and line signals? With no audio input there was an audible whine maybe 30 dB down. Perhaps this was my power supply? Or maybe digital crosstalk on the board? More tests are required. The FM chip may be "the best" in terms of spurious RF harmonics, but as a whole (including the audio performance and menu settings) this transmitter is pretty rough.
I forgot to say that if you need MPX input, then you got to get the BH1414K transmitters. If you don't know what MPX is, then you don't need that - just get ELE or QN8066 transmitter.
@@angelowasteste6343 I don't normally sell transmitters, but I may have some extra in the future from another review. I have a new 7W review coming in 1-2 weeks.
I have a vintage stereo with a nice FM tuner (Yamaha T-2). Broadcast radio is pretty horrible these days (as is broadcast television), so it never gets used. I want to simply transmit music from my pc to the FM tuner if only so that it is an active and organic part of my stereo system. Your video helped me to understand which budget transmitter choices there are and why I might choose one over another. I still don't know about audio quality, but at least I know of a couple transmitters on this list that I can try. Thanks.
16:30 I just got the 7 watt mentioned to the bottom left. Possibly something changed, or I got a bunk one, but that thing is DIRTY! Takes out 1/4 of the dial! Full power there's like 2/3 reflected watts, cleans up a bit at 2 watt out. Swapped out my 15W, minimal reflection on that one.
Many of the Qintec small 8027 transmitters, use a low grade resonator instead of a decent quarz X-tal. As it used in PLL comparator, I am wondering what will be the affect on noises/wider carrier ? Maybe just replace it with a decent X-tal and put some decoupling Capactors around the chip and checkthe results first. (just to ensure it is the chip and not the design) But for me the 8027 sound great,really perfect. But you must ensure you cap your audio at 15khz, as it is not filtered. (and indeed use limiter and audio chain if you want to sound loud)
Thank you, sir. Your other comment was not completely visible to me. Did you use PLL/VCO in these new transmitter kits? If not, you should consider it in the new version. It will be better than 1414K.
@@spectra-man Warner RF transmitter do not use BH1414K because the sound quality is not so good, use my own PLL/VCO for this new type fm transmitter, some Car cinema use this fm transmitters in USA
I bought a Retekess TR508. Any idea what FM IC those are? I looked inside and see a microcontroller of STC8G1K08. Not sure what that means. I think mine has grounding issues, and I'm not sure if that is inherent in all of the TR508 or not. If the transmitter is on and is within several feet of my mixer, whether it's plugged into the mixer or not, there is a terrible humming noise when I turn up the volume for channel 1 on my mixer. The only difference between channel 1 and the rest of the channels on the mixer (ARTPro USBMix4) is that channel 1 has phantom power. Though the humming is still there whether I have phantom power on or not, whether I have a mic plugged in or not, and the hum is in the actual audio (not just the radio listening in from the transmitter). If I touch the transmitter case, then the hum significantly lessens (though not gone), and if I turn off the transmitter, the hum is gone. So I have to have a big, long aux cable and have the transmitter far enough away that it doesn't interfere with the sound in the mixer. What in the transmitter could cause this?
Great video, lots of useful information for someone like me looking to enter the HAM community but on a strict tight budget. You mention you have built your own transmitter and don’t plan to sell it, can I ask if you are willing to share the schematics / build instructions?
Very interesting Fm transmitters presentation . What could be happen if i use one of this Qn8007 transmitter in texas...with about 30 w..can i have issue with Fcc?
Very grateful that you've done all of the R&D with these various chips. I have one with the BH1415F chip that I picked up a couple years ago to go with a Christmas light display. Out of pure curiosity, I put it on a spectrum analyzer and saw a whole mess of spurious emissions and noticed a bunch of other "undocumented features" that I'm not happy about. I'm looking to kick this to the curb for another with better audio quality. I can't see the model number on the ELE that you have. If anyone could reply with the model number I would appreciate it. Also, don't use garbage telescopic antennas on these. I built a folded dipole which gives me about 3dB of gain and makes a low power transmitter far more effective for neighborhood use. Worse case scenario, make a standard dipole with a ground radial hanging below. Both should be at 33.5" for 88MHz and 27.25 for 108MHz. Using a trash antenna will result in high VSWR and can eventually fry your final amplifier.
For anyone wondering the top left one in the video is the EL-05H but it seems to be rather hard to find and expensive
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@@ivanpoddubnyy3421 I'm still undecided about buying the ELE EL-15S. I need to know if you have it and can confirm its power is effective. I would also like to know if it's stereo or mono and if I can select this option. I need data on the stereo pilot percentage it triggers. Regards.
The 8027 is good for up to a few watts, before the side spurs are a problem I find. The Freq is off on those cheap usb powered modules too, you can pad the crystall with a cap to get it within 2Khz of dead on freq. You can filter out harmonics and spurs if needed. However none of those transmitters in the video you discussed are good enough for professional use, not even pirates should use them they are terrible, just fun toys.
I have a NIORFNIO T15A, which with an internal antenna gives interference to other stations within a radius of 15 meters, further than that it does not cause interference, I want to know if the 'ELE transmitters' give less interference than it does.
Wonder if it's possible to get RDS running on the QN8066 chip? I see on the data sheet that it supports it. However, the chip also seems to be a transceiver, so it's possible its for receive only. I can't see an MPX input pin on the chip which there is with the BH chips and a way to inject the RDS? I wonder if It's possible to do it through the audio chain, if the transmitter supports mono then it could be possible to use a stereo encoder, then in to RDS as then in to the audio? Not sure if it will work very well with the transmitter in stereo?
I've been messing around and I can get RDS through the Audio on a Chinese TX with the QN8066 chip using a basic home-brew encoder feeding it with a mono signal. There is some wine on the audio, but I think this can be filtered out with a low pass filter in the audio chain. RDS is working well. I will post up a video once I have all the issues ironed out.
@@farpointradio OK, that's very interesting. I expected the mono mode of QN8066 to be filtered of the high frequencies. I never used it in mono mode though. Pretty sure the datasheet said it was. I'm very surprised. Send a link if you make a video. Thanks.
@@spectra-man Will do, you have to modify the MPX out from the RDS to get it to show the data on radio, but It's not that much of a job. I will post a video up and show you what I did.
Hi thanks for the video. The Retekess TR-505 I've tested is far superior to the CZE-7C. 25 watt maximum but it has a problem between say .4 watts and 5 watts where a pulsing noise is generated but if you do anything in the menu the noise goes away, would you happen to know why?
Hmm, guess I missed that one. Never saw that one on ebay. It's probably not matched properly. If you saw my video on the new 30W, you will see how these lower grade transmitters put out a lot of noise unless you run them at full power. My solution is to set the power to full on the screen and lower the input voltage maybe down to 8 - 9V or how low you can go.
I've watched this like five times and I zone out about 8-10 minutes in. I think you just waffled a bit too much. 30 watter with the QN8066? Which was that?
Thank you for this video! But I found it to late, I still ordered a BH1415F transmitter....Retekess TR509 :-( The ELE EL-07 @ 26:48 with the "?" seems also to use the BH1415FIC (product information @ eBay). I´m searching for an QN8007 FM transmitter 5-25w in a case, ready to use for outdoor lasershows. recommendations? Thank you!
id like to thanks this vlogger. this makes my reference when buying my 7w fm transmitter with QN8066 . i just want to ask a question. if this fm transmitter with QN8066 is good to pair with booster transmitter pallet with 250watts output? thanks a lot.
Great video. Though it's hard to get the model numbers of some of them from the pictures. Also, I think some of these transmitters will not come back on after a power failure (someone has to push the power button to turn it back on) which is a no-go for some applications, yet few of them mention whether they do or not.
The RF noise is really bad. Don't amp it up. Sound quality was also "digital" compressed sounding. Not sure if I just had a bad setting. I used the Adafruit board to test it.
Found this video after purchase and looks like I got lucky, from the images it looks like the board I have coming is the one in the bottom right at 15:08 It will be here in a day or two so will be able to see for sure what chip it has. I already have a 45w amp so plan to run the main transmitter at 1w rather than 15w and run it through the amp but also have the option of changing the output transistor on the amp to one that will do 60w for less than £5 which is no big deal for me as I soldered the amp from a kit.
@@spectra-man interesting. It looks like the model I'm looking at (supposedly a .1/.5W "low power" one) has a shield over the RF portion, so I can't see the actual FM tx chip.
You did a very good in depth reverse engineering job I’m a old ham guy that has gone rouge LOL yes the eBay ones stay away from. We have a Camel RF from a guy in California that imported the Warner style transmitters puts better parts in that are known to give problems and tests for hours on a dummy load before shipping them out we have the 150 watt rack unit been running it for close to 10 years with no problems and is clean FM audio and does not drift ! The site has disappeared that we got it from was about $1200.00 back then . Do a spot on antennas we have about the last dominator from Norwalk electronics before they went out of business . It’s. .94 wave .
Did you know that there is st-7c that is 3.0 version. Maybe it is better than st-7c 2.0 version. If know what is difference between them please advice.the chip is stc 12c2052
@Spectraman Spectraman , At 7:36 you mention the transmitter that I have, the SD card one 7watt pll. So I've built it a few years ago and it didn't want to work properly at all, the greatest distance transmission I could get was like 300 meters. As I was just a kid I got bored with it, tossed it away at my grandma's. 6 years later now I found it by accident, and went all Jerry Reed Amos Moses on it, disassembled the whole thing, and cleared the connection points because solder wouldn't stick to them AT ALL, and after re soldering, the thing decided to give life, and work properly without overheating for the first time, and I made a big proper dipole antenna in hope it would work better this time, I calculated the antenna in that android app, made the thing out of two metal broom pipes that were hollow 22mm diameter thin metal pipes. And I put it at the top of my rooftop, and my house is like really tall and on the top of a MOUNTAIN. Fired the thing up, went for a test drive, and what I got was 800 meters (half a mile) of clear signal, and all else was just cutting out and nothing after 1 mile *approx 1,6 km*. I am still very dissapointed, because people claim that you can get 6 miles with that thing if your antenna is at a height, and my antenna is not only high, but, really high up, at full power this is my result. TERRIBLE. Also i use expensive coax tv cable about 3 meters long for the transmitter output. (i think that the cable is 75 ohm, or it says on it I think). SO, there could be more things involved, I use 13 volt 1 amp power supply, is it too weak? Is my transmitter too close to the antenna? Too much feedback power? Bad antenna? Bad cable? PLEASE HELP IF YOU CAN, or everyone, thanks in advance, means much to me, i cannot describe how much.
It's hard to give a definite answer without more equipment. You really should get an SWR/power meter. A used one can be very cheap on ebay. That way you can actually see what it's doing. Do you have a power supply with an amperage readout? Maybe when you were a kid you didn't make the proper antenna and blew the transistor? Does the heatsink/transistor get warm? The 1A power supply might be OK, but it's right at the limit. These small 12V transmitters aren't very efficient (often a little less than 50%) meaning that power supply may not be enough. 2A would be plenty though. When I first started, I thought I could get away with just transmitter, antenna, and power supply, but in the long run you will need things like this cause it's like driving blind and asking why you crashed.
@@spectra-man Yeah I need the SWR. You made a fair point, the current meter pops over 1A, so I found a big 12V ac transformer capable of 5A, made a rectifier, filtered it with capacitors, and it's capable of just under 5 amps, however, when I connected the transmitter, the reading that I got was 0,63 A. Way less than my table 1A variable PS set at 13V which reads over 1A current surge.
@@spectra-man The heatsink is always warm, sometimes it gets a little hot, but then the PC homemade temperature reading fan kicks in and cools it down, i made a beautiful alu case for it btw.
@@spectra-man While thinking about it now, I forgot to tell you an important detail, I was transmitting over a taken frequency on accident, a local radio station that has a tower about 15 km from me... could it be the cause of low range?
Ehh spectraman!! Thank you so much again for your videos!! I have a couple of these chinese xmitters but I dint recall what chips are in them but lol.....I'm still rockin a bw warehouse xmitter/exciter that I built as a kit about 25 years ago!! I can get approx 6-8kms with a home made copper pipe slim Jim! I recently picked up a warnerrf fm150a but it has issues. I replaced the roasted final but now it hunts the rf power output after 30 seconds of running. Im gonna try and borrow a thermal camera to hopefully see what is failing. It seems as there is rf getting in the b+ because voltage spikes up n down on the + rail when it starts hunting......odd huh?
Original? Which original? Almost all of these transmitters are best to find on aliexpress. Just search "X" watt fm transmitter and look for the same picture (XW). Replace X with watts.
Yes, in theory, you could connect an MCU to control it. It would be hard to get it connected to the traces, but it's possible. When you say LC parameters, I assume you mean to control the tuning circuit. That would be almost impossible.
Looking for advice....was using Si4713 adafruit for my Holiday Light Show but am unhappy with audio quality of FM transmission.....looking for an alternative with better quality audio but would like to retain RDS capability.....most people in holiday light show community use Signstek ST-05B but there is no RDS capability with that unit.....Also it lacks an MPX input ......maybe a modification to allow MPX input?......Then use a separate encoder for stereo and rds?......Any suggestions? Thank you 😊
Well, you can get better audio quality with an ELE or QN80xx transmitter, but none of the cheap transmitters have RDS. ELE says it does, but doesn't. Your only option is to go for a more expensive transmitter like PCS electronics if you need RDS and MPX. If you got a BH1414K transmitter, you can hack in RDS, but you need some soldering and electronics skills. If you have it, then you can search darkliferadio.proboards.com for the BH chip hack.
@@spectra-man thanks for the reply.....I have searched the forum and I have not been able to locate that BH chip hack post you reference ....could you maybe send a link to it or be more specific on where to look?....thank you
You know what? I decided I would rather have a good transmitter than RDS. It was nice to have RDS but not completely necessary so I ordered one of the 8066 7w transmitters with the SDcard slot...the blue one from aliexpress for $25! Now I just have to find a box for it or 3D print something😊😎
Was thinking.....what are the odds that the screen on this module is controlling the qn8066 chip with i2c? If it is couldn’t I hook it up to my Raspberry Pi just like my Si4713 was and control it like that? Maybe rewrite the plugin to adjust for programming code of the qn8066 and get it to do RDS also? Data sheet says it is capable of RDS transmission🤔. Just a thought.....any feedback?
@@iamwally Sorry for delay. Yes, you could theoretically do it, but you'd have to break the connections on the PCB and solder connectors to the PI. Also, it uses a pretty complicated init code. The RDS is very limited. It won't let you display long stuff like song name AFAIK. 7W is plenty of power - it will go too far :)
Thanks for this video. Can you recommend a portable FM transmitter that would be good for 1km vehicle to vehicle transmission in a busy city? Sonic quality highest possible. 12 volts or lower is a bonus.
I realy appreciate your work. I have seen all your videos and they are useful. Here I must give some clarification. By the data sheet, regarding the spectral spurs there are no significant difference between BH 1414K and QN 8007. But QN is slightly improoved. This Made in China transmitters up to 30 Watts RF Power are not EXCITTERS. They are quite good as LP FM standalone transmitter. No further amplification !!! Soundwise, BH 1414K is very, very good. But, to achieve good (professional radio station) sound, it demands a lot of knowledge and additional equipment. 31 band equalizer, at least one compressor/limiter device, this is if you want to make program by studio connected to audio input of transmitter. If you want to air USB device recording, you must process all sound recordings by special sound filter curve and compressing/limiting . This demands some knowledge with experience. If you have done this process properly, your China FM Transmitter will sound as good or even better than Professional FM Radio station.
In my early youth (mid seventies) there was great revolution by Made in Japan "HI-FI" eqiupment. People liked more sound of FM Stereo radio stations (recorded on cassete decks) than turntable sound. So they considered that FM Stereo is Hi-FI (and turntable not). The truth is opposite. FM Stereo is very Low FIdeliti, but sticky to the ears. That comes from processing sound before FM Stereo transmitter. The trickyness comes from the fact FM Stereo sound consists of 4 elements. Only one L+R is in the original human hearing sound range. There is 19 kHz pilot tone we can not hear, but this sound runnes stereo decoding process combining L+R and L-R, R-L signals which are in the range we can not hear. This facts are main reason why sound before modulation in transmitter must be processed. And additionar reason is "loudness", for the listener who are using low grade radios. With small narrow range speakers, different bad acoustic enviroments, but it is demanded in all this occasions sound od FM Stereo radio station must be attractive,....
You can't rely on the datasheets to always give accurate info for noise on these chips cause they aren't meant for real transmitters. I think QN8007 sounds better than any BH chip, but it has more phase noise. 1414K has less phase noise, but it has a porcupine around the carrier from no filtering the MPX internally. Overall, I think 8007 is better. I don't use most of these transmitters. I have PCS electronics and BW broadcast TXs. I just make this video for curiosity and for people who want to buy a cheaper transmitter.
@@spectra-man Thank you for the answer. I have for the years PCS transmitter intented to be a excitter. I tested two Made in China LP FM stereo transmitters branded as "Niorfnio". One is 15 W (mesuring shows 19 W) and 25W measuring shows 30 W (even burned 25 W rated dummy load). And , both have problems with spurious emisions when output power setting is low. But soundwise they are great. Of course after the processing the sound. I was the owner of licenced radio station, so I like more XLR ballanced audio inputs, they can not be interferred with RF or lenght of audio cable. I prefer stereo coders separate from PLL. And setting the output power via trimmer potenciometer. But thats pricy professional style of transmitter (good filtering the spurious and harmonics, 70 dB or better). For intented use as backup or even LP FM transmitters (educational, community or RSL,..Radio Stations.) Chinese transmitters are not that bad if are used by qualified persones. Using antenna VNA and spectrum analisers are must for qood setting of this transmitters, feeder cable and antennas. Best regards.
@@jazzforever4631 wow. I like how you broke this down. I have a question if you don't mind. I have a 150watt and I don't understand what the external modulation feature does. It goes from mute all the way up to 15db but I don't understand its function or purpose. Can you help with and explanation? Also, mine is a 5.0 version and as far as audio im using XLR Balanced inputs and audio is compressed before it hits the transmitter and it sounds superb. My input volume is set at -1.0 db which is strange but other than that and an internal error of some sort its still working.
@@DjSmoothNY Well Rohm BH 1414 and similar are designed for micro power use. Mostly MP3 players for car radios having no SD or USB. In another word they have a lot "dirty artifacts" regarding stereo multiplex. So if you amplify their signal, you can hear harmonics all over FM spectrum. Especially if they have LCD or OLED display. The harmonics and other bad artifacts are lower when 15W and 25W transmitters are running 50% or more power. So I say as standalone LP FM transmitters they are quite O.K. But as excitter for the further RF amplification, Quintech based 1,5W , 7W, 15 W. Are significantly better as they have more MPX spectral clarity and 5 dB lower harmonics.
The BH1414 single ic awful, its worse than the 8027 the spurs can be managed, and that 30 Watt tx u showed as being the better, has big issues, you need to set the power to 30watts max, else its splatters the band, I found you can drop the power down by reducing the dc supply, works fine, but its unstable at full power, i run the thing for a few hours only to find it suddenly splatters the band with large spurs everywhere. All those medium powered ebay transmitter are awful, I got 15w module that keeps drifting out of pll slightly and then suddenly corrects every few seconds and makes a pop sound in the audio, just crap, spectrum was not that clean either. You wonder what the guy was thinking who designed these and put them on the market.
I have bought an ELE EL-15s in 7 W version and can verify that the near spectrum is very good! BUT can also tell you that second harmonic suppression is extremely bad! At full power at 88 MHz it is 22 dB down, at 1W -14 dB and at 0.3W (lowest power) it is only -9 dB. Second harmonic is thus fairly constant around 15-16 dBm (30-40 mW) regardless of output power, which is at least 50 db worse than permitted in the EU and cannot be used without an external LP filter. Another disappointment is the very strange AGC function on the AF input which cannot be switched off.
I had the same display issue on my broadcast warehouse kit many years ago. The guys sent me a new pic for it and it's still working great some 20 or so years later!!
Thank you, for the explanation. A lot of information from you! TNX I have some chinese fm tx...... the CZE-01B Czerf Pll Stereo Fm-tx Mono Radio Broadcast Station 0-1W is crap.....produce mirrors on much frequencys. The other 1 is like you described St 7c 1W/7W Fm Stereo Radio-tx. Last one CZE T251 . 73 de PA3GEO Robert
Your videos are very good. I have a question 🤔 What is external modulation on these transmitters and what does it do? I have one with this feature but I don't really understand its purpose.
Hmm. Do you mean MPX input? That's basically the same thing as external modulation. It's for if you want to hook up an FM audio processor. Most of the cheap transmitters don't have it, only the more expensive ones. It's good to have cause you can make your station sound very pro. You could try using stereotool with it cause most FM audio processors are overpriced. If you do use stereotool, it's a bit more complicated to set up though. You need to send ur mixer into the comp's line input, that goes through the stereotool software and then that goes out to the MPX. You need a studio level sound card. Then you'd need a second sound card to hook the comp up to the mixer cause both in and out already used by stereotool. It's cheaper, but as you can see, it's kind of annoying and complicated, so if you can afford an audio processor, it will be much better.
@@spectra-manThe thing is, I really don't know if its MPX because it doesn't say that in the settings but I'm sure your correct. I've tried stereo tool and its so complicated to hook up. I had it working once already but found that the presets were horrible. To tin can sounding for me. Not to mention they want 600 usd for the full version. I may as well buy an external unit for that amount.
@@DjSmoothNY Message the manufacturer just to be sure. I just bought one of these optimod processors. You might be interested: prostudioconnection.com/collections/orban-optimod-processors/products/orban-optimod-pc1100-v2-win10-compatible-on-air-processing-pci-card-xlr-w-cables-refurbished
Have not tested it yet, but I will make a video on it in the future. It's the best value for money I could find. All the other good processors are $1000+. And optimod has been known in the industry as the best processor. You need to make sure your PC has a PCI slot in it.
Optimod pc1100 won't be better than stereotool. You can run the station with only 1 computer with stereotool using the soundcard output. Remember to calibrate the Low frequency tilt. If you want external processing you will need a modulation monitor too
good day to you suir idol, i would like to ask if what kind or a halfwave GP antenna is suitable for chinese fm transmitters sir idol... that my question sir idol
You will find them on aliexpress. From there you can order to pretty much any country. Aliexpress has more options than ebay or amazon. Amazon only has the BH1415F. I can't give a link cause I don't know which one you are looking for, but it won't be hard for you to find. Search 7W FM stereo PLL or 30W, etc.
Hi, thanks for your informative video. I have niorfnio t15b, every time i go on air, it can be heard from other stations than the one selected. How can you help me with this issue.
It's because the BH chip has a wide signal. You need a better transmitter without BH chip like I said in the video. But remember, when you put the receiver near the transmitter (EVEN on a very GOOD trans), it still might block other stations. Move farther away.
Thanks for posting this good and informative Video, with all it´s Informations. I also have a transmitter here, prolly using the 1415F chip, stating it puts out .5Watts. Occasionly (really rare) use it for some private broadcasting, but thinking about it, the last 2-ish years it just stood in my shelf. I´ve checked the harmonics (double, tripple Frequency etc) and it is supressed well enough to make me feel ok using it. The audio quality is not the best. The stereo seperation is by ear quite good, but the bass-sounds don´t sound to good. There seem to be no real "low" frequencies, and the bass that is transmitted just sounds... cheap... hard to describe. I´ve got another transmitter that has no volume / mic controls on front. Just a frequency up / down key and the display (the on off key is at the back). Also a .5Watt version bc I think for some "hobby neighbour" broadcast this is far more than enough. However, this transmitter (in a silver metal case) puts out far more power than the CZE one (I think the other .5Watt Tx is a CZE, its the same housing as your CZE7 Watt-er but with .5Watts only)... anyhow, the sound quality is excellent to the ear, and also the harmonics are well supressed. Unfortunately it broke by itself... I used it with original antenna (which I know, may not have had the best SWR, I didn´t measure it...), and what happens now, is that it cycles the power. So it would transmitt with full .5W for like 2 seconds, then go to like ...1/2mW (that´s how the range is) then go back to .5Watt aggain... maybe it´s lose solder connection which bends back and forward as the final transistor heats up? Whatever. ... What do you think of the BH1417 Chip? The one with some fixed Frequencies either at the low FM band or the top FM band... Have you ever heared of the "Veronica" Transmitters? They claim to be professional transmitters. They have seperated VCO / PLL (and PLL is lots of ICs not a single IC) but they run the oscillator at half frequency for better frequency stability. In a forum people tested these, and said that they produce lots of harmonics or... not so good signal bc the doubler circuit may not be perfect. I do have one of these myself (1Watt) but in all the years I own it, I just plugged it in a few times mostly for testing... It´s more like a "novelty" item to have... because it has lots of memories of my childhood for me. You could get / test one of these? What do you think of the combination(s) used in wirless speakers or headphones ... the ones that use the old BA1404 and use it´s internal oscillator, but "steer" it with an external PLL? There´s a company here selling a transmitter based on the SI74 something?? Chip... it is said, that the signal quality is ok for super weak output power, but it´s very "broad" so better not amplify it. Also have one of these transmitters - to me the audio sounds excellent, nearly as good as a professional station (others think that too) but my Tx has issues with its signals because it can for example not log in at Frequencies over 100MHz... Just a "few cents" from me. Good Vids you make there :)
Hi Stefan. I used to watch your electronics vids, but I just forgot about your channel. You also helped me with a simple AM schematic many years ago :) You seem to have a better understanding of general electronics than me. That's a lot, but here we go... Yes, it is true that the BH series of chips have bass distortion. The BH1417 is said to have a slightly better audio quality than the BH1415 due to a better stereo generator, but it still uses the same switching type design. The BA1404 is also marginally better than the 1415, but haven't tried it personally and it lacks the PLL circuit. I think maybe adding your own external PLL could be good. Yes, I've heard of veronica. I have an AAREF clone of the board (1W). The signal spectrum is very clean and the audio quality is great. But today, it's unnecessary to have so many components and it was cloned by a guy with not much RF knowledge. There are some devices from analog devices which could really simplify the design. It's a shame they only come in tiny packages like QFN. But I think if you want to do hand built, the best option would be your own VCO + MC145170 in DIP package (like the radiomaster). You could even get one of those self contained mini-circuits VCOs (but they are kind of expensive and not sure if still available). That's what stefan dunifer did on his free radio berkeley transmitter. You also SHOULD REALLY BE AWARE of the PKB and RDVV: www.amateurradioshop.nl/webshop/bouwkits/fm-broadcast/ They have an EXCELLENT VCO with many diodes. You can see they have a 6W sender kit and just a PLL kit. Maybe the PLL could work with BA1404.
Hello Spectraman, many thanks for your video, very informative. Do you know if the QN8007 is still on production? If so, where can we buy it. Best regards.
I don't know, but you can still get it I think on alibaba and a few on ebay. If you want to make your own transmitter with it, just know that it's very hard to solder properly. I spent a lot of time just trying to solder it. I hope you just use it for yourself though cause I might be selling my transmitter and I was kind enough to tell everyone the secrets, so I'd appreciate it if you don't steal the idea. It took me a very long time to find the best chip cause most of them don't tell you how clean the signal is; you have to test it yourself. If you sell only to your country (not US) like Italy or whatever, then I don't care.
@@spectra-man Hello, I got a few QN8007B from ebay. Made a small test board with a buffer-follower (S9018) and a amplifier for +20dBm output (BFG135). Very pleased with the results! No the same as a discrete VCO with PLL, but quite clean compared to the Si4713 that I have tested before. Audio quality is not perfect, but very good, I found that in Mono the audio sounds better. Still have not tried the RDS. The only thing I have not solved is some spurs that appear from around 107 Mhz and up, very noticeable on 107.9 Mhz, they are at +-450 and +-900 Khz. On the rest of the band all is clear as far as I can see on my TinySA. Will try to get a real SA to check further. I promise not to sell this in the USA if I make a full transmitter , I'm very far away from there! Again many thanks for sharing the information on the QN8007, take care
@@diegoccs I don't think I tested above 107 on the spectrum analyzer (only audio test). I use low band, so I only checked that. I can test it and let you know. Maybe make a video. A design with MMIC fed into RQA0009 can make a few watts in two stages. By buffer follower you mean an attenuator to reduce noise in the chip? If not, that is one thing that was recommend to me by PCS. You amplify it more than necessary, put an attenuator and then amp it more. It will reduce potential reactions from the amplifier inside the chip causing noise.
@@diegoccs Also let me know if you test I2S digital audio input on it. You can probably find a module for that on ebay too. I want to know if it's working with the QN8007. It says it has this feature of digital input.
Awesome video idea, I really haven't seen another channel that does stuff like this. What do you think of building an fm transmitter from an FPGA + DAC?
Thank you :) That might be good, but I don't know how to program FPGA. I program only in C type languages. I don't think it would be any better than DDS + DSP though. If you were trying to make some custom signal, then it could be better, but for normal FM broadcast, I don't see an advantage. SDR would be very similar I would think. I do have some experience with that. LimeSDR is still not here, but at some point I will be using that.
I have the niorfnio 15watt.. been on air about 3 years...still sounds good, and no FCC warnings yet.. idk. I dont think they give a rats ass unless your on top a comercial station and they request that the fcc " fix " the issue with you transmitting on top of them..
As i didn't Test yet >1. QN8007 and 2. QN8066 < ..... The BH1414K is the Best IC, compared with the others IC's ((except 1. QN8007 and 2. QN8066 As i didn't Test yet )) that i Used and Tested......BH1414K has very good Audio Modulation but it has a problem in Carrier S/N. (has a noticable"hiss" noise in carrier than some others IC's). BH1414K DataSheet declaires that it has a S/N ratio of -55dB Min / -68dB Normal, 🤔 but i think the Normal S/N is -55dB for this IC....and this value is not good for me. 😠 This S/N carrier problem of course affects, and increase the "hiss" noise on carrier when use it in Stereo Mode. It's not such a serious problem, but it is quite noticeable if we are seriously interesting about the best Fm TX IC in market. Also, I take very seriously the Spurious/Harmonics dBc/dB values and the BH1414K is the best in that case...Unfortunately...😢 the carrier S/N ("hiss") problem is quite serious for me, so my rating for BH1414K IC is 8/10...and still the best than the others IC's that i tested. If BH1414K it doesn't had the S/N carrier problem my rating it will be absolutely.... 10/10 !!!!🙂
Who uses these transmitters? Aren't they highly illegal. I doubt if they would pass the FCC requirements for FM Licensed LPFM I'm assuming they must be used in China. 100 watts on FM? Surely you aren't talking about broadcast. I bet the pirate broadcasters in Manchester UK (there are lots of them), causing OpCom some serious headaches.
Kt0803 is not a bad one.it has a well defined digital interface . When the i2c programming done very well it has awesome output like qn8007 and bh1415. so please try to program very well in c or cpp with respect to the datasheet
Are you sure? Have you seen the output on a spectrum analyzer? It looks like a tit :) Do you mean if you program it differently, it won't look like a tit?
A lot of great information..But for those who don't want the FCC knocking on our door.. How about reviewing Part 15 FCC Certified FM transmitters in the future.. Great information for church, drive-in movie theatres,etc. Thanks.
The FCC is complaint driven, unless you're really interfering with another licensed station or not minding your own business, I doubt they will waste time and money to come hunt down a 15Watt broadcaster.
Don't you see it? It's in the BH1415F category. It's the gold model in there, but silver is the same thing. I don't have one, but the supplier told me it's BH chip. So not 100% sure, but like 90%.
Hi, thanks for your informative video. I have niorfnio t15b, every time i go on air, it can be heard from other stations than the one selected. How can you help me with this issue.
Ive got the unassembled 7w one 15:55 (Quintic) the 3.5mm jack doesnt work. It produces high-ptched beep noises when I hooked up my phone or PC to rebroadcast DAB-only stations which is weird but good thing: no harmonics. I would have to use the built-in SDcard slot. Also, the antenna port doesnt work (I tried copper wire connected to the pin since I dont have a 50 ohm antenna. The distance is just 6 feet away, dissappointed. 7W is a lie. UPDATE: The jack works but the sound is very low (like BBC Radio 3). Youll need a receiver with a really loud speakers! I tried turning on compressor and it doesnt work.
Probably something wrong with the kit. I found that it's not usually a good idea to buy kits from China, only the pre-made versions are good. When you get a kit, the Chinese put used/broken components in there and sometimes they forget stuff. Better to get pre-made cause it's not very expensive. I had this happen to me a few times with an MRF186 amplifier kit.
UPDATE: The port I plugged was a green jack which is a microphone Jack anyways. The transmitter now works but I'm waiting for a 50 ohm antenna. I got 2-inch distance from a old used wires connected to a pin which is weird maybe it is not callibrated. Luckily the tranmitter didn't blow up but when I moved the wire it stopped transmitting until I replug the cable.
@@bioskahabinivous9906 Don't use it without a proper antenna! The 7W transistor might blow out. You might want to get a couple extras just in case. I don't think they are too expensive. Then you can play around with it.
This is informative, but showing a unit, circling it and saying "this one" doesn't tell us what model it is. I'd like to see a list of what each one actually is, otherwise it's just guesswork on the viewer end.
See, the problem is that many of these transmitters are model-less and brand-less. I think I said in the video all the models of the ones that actually have model numbers. So in order to find these transmitters, you just need to look on aliexpress or ebay under generic search terms.
@@spectra-man We both know that a single design in these Chinese products is duplicated many times over into similar-looking products, some of which vary widely in quality, so matching a fuzzy image is literally a shot in the dark. What about for instance the one at 26:10? You say you own it? If the images were sharper we could read them, and *some* of them we can but otherwise it seems unnecessary guesswork, and I see several others already made the same point. I do recognize the one at upper left 19"22 as a *CZE-15B* if that helps anyone. If that's the CZE-T251 to its right there seems to be conflicting info on that one, as Eddy Bergman says the 251 uses the BH1415F, while the 15B does use the 1414 as indicated. You've got the 251 using the 1414. I don't know which is correct, just looking for reliable info before making a(nother) purchase.
@@DJTKarlsson Not really. I did end up picking up one of the ELE units, and I have to say it's disappointing. Stable, but doesn't really sound great. And I'm comparing to much cheaper stuff.
Do you mean the QN8066 or QN8006? Cause the QN8066 is very common and pretty good for a single chip design, but not PLL/VCO quality. The QN8006 I believe is slightly better because it's basically just the QN8007 with a receiver built into it as well.
@@spectra-man I bought a PLL board that has this QN8006 chip (not the QN8066). I didn't find more tests with this chip on the internet, so I decided to ask the question for you. Thanks for your attention!
Looks like there's already two transmitters I missed. If you go to my site: dosaidsoft.com/wp/ Scroll down until the end of the right side column and click the donate button and then I will buy more of these transmitters to review. Thanks!
@Spectraman Spectraman , At 7:36 you mention the transmitter that I have, the SD card one 7watt pll. So I've built it a few years ago and it didn't want to work properly at all, the greatest distance transmission I could get was like 300 meters. As I was just a kid I got bored with it, tossed it away at my grandma's. 6 years later now I found it by accident, and went all Jerry Reed Amos Moses on it, disassembled the whole thing, and cleared the connection points because solder wouldn't stick to them AT ALL, and after re soldering, the thing decided to give life, and work properly without overheating for the first time, and I made a big proper dipole antenna in hope it would work better this time, I calculated the antenna in that android app, made the thing out of two metal broom pipes that were hollow 22mm diameter thin metal pipes. And I put it at the top of my rooftop, and my house is like really tall and on the top of a MOUNTAIN. Fired the thing up, went for a test drive, and what I got was 800 meters (half a mile) of clear signal, and all else was just cutting out and nothing after 1 mile *approx 1,6 km*. I am still very dissapointed, because people claim that you can get 6 miles with that thing if your antenna is at a height, and my antenna is not only high, but, really high up, at full power this is my result. TERRIBLE. Also i use expensive coax tv cable about 3 meters long for the transmitter output. (i think that the cable is 75 ohm, or it says on it I think). SO, there could be more things involved, I use 13 volt 1 amp power supply, is it too weak? Is my transmitter too close to the antenna? Too much feedback power? Bad antenna? Bad cable? PLEASE HELP IF YOU CAN, or everyone, thanks in advance, means much to me, i cannot describe how much.
PCS is a PLL/VCO so it works as a professional transmitter. These work like the little transmitters for a car, but amped up. It's not #1 though. I'd say NRG PLL PRO or RadioMaster is the best you can buy, but they are much more expensive and PCS is good enough you won't notice any difference between them.
@@antonio1681 Yeah, it's worth it. It might only sound a little better, but the difference is in what you can't hear. And PCS is clean enough for amps unlike BH chip.
@@spectra-man www.ebay.com/itm/150W-76M-108MHz-FM-Stereo-Transmitter-RF-Power-Amplifier-Radio-Station-Ham-/122824900269?_trksid=p2349624.m46890.l49292 Is this any better than the pcs electronics? Also, can this be changed to 75uS?
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I have a CZE 7C with a BH1415F, and it distorts too much in the bass frequencies. I have to adjust the processor to the point where I lose the bass in the music I transmit to avoid exceeding modulation. Also, which one of these transmitters has a stereo pilot that doesn't overmodulate the final carrier? In the CZE 7C, the stereo pilot reaches 24% modulation, and I can't lower it. Which one do you recommend then, one that doesn't have distortion and has a stereo pilot of at least 10%? Greetings, your video was very helpful.
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This is by far the best review of chinese transmiters in RUclips. I was concerned about spureous emisions and harmónica and you solved all my doubts. I apreciate your help.
Very interesting ,good presentation enjoyed watching ,take care 73 de ve3hip from Welland Ontario Canada 🇨🇦
I saw in the documentation that the Quintic QN8006 has RDS support. I can't wait for an antenna and test this out with Stereo Tools! Bloody excited!
It doesn't work like that unfortunately. The chip would have to be programmed to support it. I'm not even sure if it has full RDS. I think only partially. When you use stereotool, you need to make sure RDS and MPX are disabled. Everything else like AGC will work fine.
@@spectra-man but why had someone on the internet managed to get RDS to work on CZE 7W transmitter using StereoTool?
@@MiiMaker Cause they probably bypassed the stereo gen portion of the chip and sent it right into the VCO. I think it's only possible with that chip. On other chips like the quintic chips, they are all digital and integrated, so you can not do that. I guess you could see that as one of the downsides to those chips. I never used RDS cause I don't like the way it spreads out the signal even more. I like it to stay as narrow as possible.
@@spectra-man Plus, RDS increases a chance of getting caught by the FCC/Ofcom. The station name may not be on their licensed-stations list.
The one @18:05 are great FM transmitters. Clean and on point with great quailty. We have been running them for years.
plus how can I get one
You know I've bought 5 of these on Ali Express, they keep saying "DELIVERED" always to someone with a fake name, like Chad Chaddington (I live in Australia so that's not even a remotely feasible name here) and never actually arrive. Idk if they're just not prepared to sell them as cheap as they are going for or what, but they keep refusing to send what I buy.
Awesome presentation. This was a great dump of much needed information, thank you.
You're welcome. Let me know if there is another vid you'd be interested in.
I learned more in the last 20m about Chinese FM than I ever did on rqdionecks
Thank you :) Some of the radionecks guys are very smart, they just don't take the time to make a detailed video.
I've tried the shit QN8027 in the Little 1mw ebay tx module, and found there was a few spurs at +-12Mhz on each side of the carrier, but is nearly -35 and -40 dbc not 25 -15dbc like yours. I added a 1Watt rf booster amp on it, but used a tuned ring and stub ant it has a narrow bandwidth and the spurs end up -60dbc down, I tested the band splatter with a fm radio just meters from the transmitter and yes its like faint second station appearing across the band, but its so weak there is no way it will interfere with another broadcaster. The sound is good, you can actually plug the thing in and it powered via the usb socket and it comes up as a sound card CD002 you send digital audio directly to it. It sounds is surprisingly good.
Thanks for sharing your thoughts on this topic. I've been looking at fm x matter. You really opened up a lot of research on this, great.
Rid on maui
Great video. The cussing made it even better. Usually these videos are so dry and boring, made it more exciting haha
I got the one at the lower left @15:46. I got it from "SZHQ Eelectronic [sic] Store" through AliExpress for about $30 including shipping to the US. It came without any documentation. Here's what I figured out:
The DC input is specified at 12 volts at 1.0 Amp. It does not come with a power supply, so I used one I had on hand: 12 V up to 3 amps.
The audio input on the heatsink side is apparently the stereo "line level" input. I presume the other is "mic level"; its tip has 5 volts on it (for a condenser mic?).
On startup, a momentary message appears in Chinese. Google translate said "This kit is only for sale abroad. It is strictly forbidden for sale or use in China. Violators shall be liable for all legal responsibility!!!" There is a sticker on the heatsink that says the same thing. I guess the Great Firewall can't stop FM radio.
After the Chinese warning, a settings screen appears. There are a total of three parameters that can be adjusted: "FRE", "VOL," and "PO" (frequency, volume [modulation level], and power). There are three buttons along the right side of the display; let's call them UP, MENU, and DOWN. To adjust the parameters: press and hold MENU for 4 seconds. The FRE item is highlighted, and the UP and DOWN buttons will adjust the frequency in 0.1 MHz steps. Once FRE is highlighted, pressing MENU highlights each other parameter in turn. Changes take effect immediately.
VOL has a range of "0" to "30," and came set at 30. At 30, only tiny hint of audio was heard. It wasn't like it was very quiet, but more like only the loudest parts were punching through. Only by LOWERING the VOL setting to about 19 could audio be heard. It was like there was a DC bias on the audio and the VOL setting was amplifying and pushing the whole signal into clipping. This was with the line level input; I did not try the mic input. I suppose the mic and line level signals are summed at some fixed ratio? And the VOL adjust affects the sum?
The "PO" power setting goes from "0" to "300". I used a Surecom SW-102 meter (ruclips.net/video/3GbvHtnK-eI/видео.html) into a dummy load to measure the power. The SW-102 is designed for 125 - 525 MHz and I had set the transmitter to 106.5 MHz, which may explain why it only read "1.53" watts at setting "300". Or maybe it really only puts out less than 2 watts? Lowering the PO setting lowered the power as low as "0.071" watt at setting "100". Below setting "67" the power jumped up to full power again! Strange.
After running about an hour at max power, the heatsink was 21 deg C above ambient.
It sound like there is pre-emphasis, but there is no pre-emphasis adjustment; I don't know what it is set to (50 or 75 uS?).
There is an SD card slot, but no menu item refers to it. Perhaps plugging an SD card with mp3 files will cause them to be played? And summed to the mic and line signals?
With no audio input there was an audible whine maybe 30 dB down. Perhaps this was my power supply? Or maybe digital crosstalk on the board? More tests are required.
The FM chip may be "the best" in terms of spurious RF harmonics, but as a whole (including the audio performance and menu settings) this transmitter is pretty rough.
For the power jack, is the pin positive or negative?
I forgot to say that if you need MPX input, then you got to get the BH1414K transmitters. If you don't know what MPX is, then you don't need that - just get ELE or QN8066 transmitter.
what you selling and how much
@@angelowasteste6343 I don't normally sell transmitters, but I may have some extra in the future from another review. I have a new 7W review coming in 1-2 weeks.
I have a vintage stereo with a nice FM tuner (Yamaha T-2). Broadcast radio is pretty horrible these days (as is broadcast television), so it never gets used. I want to simply transmit music from my pc to the FM tuner if only so that it is an active and organic part of my stereo system. Your video helped me to understand which budget transmitter choices there are and why I might choose one over another. I still don't know about audio quality, but at least I know of a couple transmitters on this list that I can try. Thanks.
One flaw I have discovered with many of these transmitters is the audio is very muddy due to the Pre-Emphasis being set incorrectly.
Really great video! I would be pretty interested in your FM transmitter, 1w is good for me!
Excellent video presentation, cleared up a lot of information, thank you
16:30 I just got the 7 watt mentioned to the bottom left. Possibly something changed, or I got a bunk one, but that thing is DIRTY! Takes out 1/4 of the dial! Full power there's like 2/3 reflected watts, cleans up a bit at 2 watt out. Swapped out my 15W, minimal reflection on that one.
Legitimately incredible video. Thank you so much!
Many of the Qintec small 8027 transmitters, use a low grade resonator instead of a decent quarz X-tal. As it used in PLL comparator, I am wondering what will be the affect on noises/wider carrier ? Maybe just replace it with a decent X-tal and put some decoupling Capactors around the chip and checkthe results first. (just to ensure it is the chip and not the design) But for me the 8027 sound great,really perfect. But you must ensure you cap your audio at 15khz, as it is not filtered. (and indeed use limiter and audio chain if you want to sound loud)
Very good review about fm transmitters from China, Thank you Spectraman
Thank you, sir.
Your other comment was not completely visible to me. Did you use PLL/VCO in these new transmitter kits? If not, you should consider it in the new version. It will be better than 1414K.
If you use PLL/VCO or DDS in the new kit, I will buy it and make a good review for you.
@@spectra-man Warner RF transmitter do not use BH1414K because the sound quality is not so good, use my own PLL/VCO for this new type fm transmitter, some Car cinema use this fm transmitters in USA
I bought a Retekess TR508. Any idea what FM IC those are? I looked inside and see a microcontroller of STC8G1K08. Not sure what that means. I think mine has grounding issues, and I'm not sure if that is inherent in all of the TR508 or not. If the transmitter is on and is within several feet of my mixer, whether it's plugged into the mixer or not, there is a terrible humming noise when I turn up the volume for channel 1 on my mixer. The only difference between channel 1 and the rest of the channels on the mixer (ARTPro USBMix4) is that channel 1 has phantom power. Though the humming is still there whether I have phantom power on or not, whether I have a mic plugged in or not, and the hum is in the actual audio (not just the radio listening in from the transmitter). If I touch the transmitter case, then the hum significantly lessens (though not gone), and if I turn off the transmitter, the hum is gone. So I have to have a big, long aux cable and have the transmitter far enough away that it doesn't interfere with the sound in the mixer. What in the transmitter could cause this?
Great video, lots of useful information for someone like me looking to enter the HAM community but on a strict tight budget. You mention you have built your own transmitter and don’t plan to sell it, can I ask if you are willing to share the schematics / build instructions?
You can buy a baofeng hand held radio for $20. Have you looked at those?
I have a t251.. I don't know if they changed it at some point, but mine has the bh1415f, not the bh1414k.
Very interesting Fm transmitters presentation . What could be happen if i use one of this Qn8007 transmitter in texas...with about 30 w..can i have issue with Fcc?
Looking for a quality FM stereo encoder. What's your opinion of the RBS-RF102 from Robonson Engineering Co sold on Etsy?
I’d prefer to purchase one of your 15 watt units… can you please advise on how to get more info to order?
Very grateful that you've done all of the R&D with these various chips. I have one with the BH1415F chip that I picked up a couple years ago to go with a Christmas light display. Out of pure curiosity, I put it on a spectrum analyzer and saw a whole mess of spurious emissions and noticed a bunch of other "undocumented features" that I'm not happy about. I'm looking to kick this to the curb for another with better audio quality. I can't see the model number on the ELE that you have. If anyone could reply with the model number I would appreciate it.
Also, don't use garbage telescopic antennas on these. I built a folded dipole which gives me about 3dB of gain and makes a low power transmitter far more effective for neighborhood use. Worse case scenario, make a standard dipole with a ground radial hanging below. Both should be at 33.5" for 88MHz and 27.25 for 108MHz. Using a trash antenna will result in high VSWR and can eventually fry your final amplifier.
Fm transmitter ELE EL-15S
For anyone wondering the top left one in the video is the EL-05H but it seems to be rather hard to find and expensive
@@ivanpoddubnyy3421 I'm still undecided about buying the ELE EL-15S. I need to know if you have it and can confirm its power is effective. I would also like to know if it's stereo or mono and if I can select this option. I need data on the stereo pilot percentage it triggers. Regards.
The 8027 is good for up to a few watts, before the side spurs are a problem I find. The Freq is off on those cheap usb powered modules too, you can pad the crystall with a cap to get it within 2Khz of dead on freq. You can filter out harmonics and spurs if needed. However none of those transmitters in the video you discussed are good enough for professional use, not even pirates should use them they are terrible, just fun toys.
I have a NIORFNIO T15A, which with an internal antenna gives interference to other stations within a radius of 15 meters, further than that it does not cause interference, I want to know if the 'ELE transmitters' give less interference than it does.
Dear Spectraman, does TZT ELE15 W based on Quintec, have "radnom-play" function? And sre there some protection over high SWR? Best Reagards
22:56 The "Elechouse FM Transmitter V2.0" also has this chip.
Wonder if it's possible to get RDS running on the QN8066 chip? I see on the data sheet that it supports it. However, the chip also seems to be a transceiver, so it's possible its for receive only. I can't see an MPX input pin on the chip which there is with the BH chips and a way to inject the RDS? I wonder if It's possible to do it through the audio chain, if the transmitter supports mono then it could be possible to use a stereo encoder, then in to RDS as then in to the audio? Not sure if it will work very well with the transmitter in stereo?
I've been messing around and I can get RDS through the Audio on a Chinese TX with the QN8066 chip using a basic home-brew encoder feeding it with a mono signal. There is some wine on the audio, but I think this can be filtered out with a low pass filter in the audio chain. RDS is working well. I will post up a video once I have all the issues ironed out.
@@farpointradio OK, that's very interesting. I expected the mono mode of QN8066 to be filtered of the high frequencies. I never used it in mono mode though. Pretty sure the datasheet said it was. I'm very surprised. Send a link if you make a video. Thanks.
@@spectra-man Will do, you have to modify the MPX out from the RDS to get it to show the data on radio, but It's
not that much of a job. I will post a video up and show you what I did.
@@farpointradio I'd also like to see
Hi thanks for the video. The Retekess TR-505 I've tested is far superior to the CZE-7C. 25 watt maximum but it has a problem between say .4 watts and 5 watts where a pulsing noise is generated but if you do anything in the menu the noise goes away, would you happen to know why?
Hmm, guess I missed that one. Never saw that one on ebay.
It's probably not matched properly. If you saw my video on the new 30W, you will see how these lower grade transmitters put out a lot of noise unless you run them at full power. My solution is to set the power to full on the screen and lower the input voltage maybe down to 8 - 9V or how low you can go.
I've watched this like five times and I zone out about 8-10 minutes in. I think you just waffled a bit too much. 30 watter with the QN8066? Which was that?
Thank you for this video!
But I found it to late, I still ordered a BH1415F transmitter....Retekess TR509 :-(
The ELE EL-07 @ 26:48 with the "?" seems also to use the BH1415FIC (product information @ eBay).
I´m searching for an QN8007 FM transmitter 5-25w in a case, ready to use for outdoor lasershows.
recommendations? Thank you!
Very Informative...Thanks.
id like to thanks this vlogger. this makes my reference when buying my 7w fm transmitter with QN8066 . i just want to ask a question. if this fm transmitter with QN8066 is good to pair with booster transmitter pallet with 250watts output? thanks a lot.
do you know if exist a PCB with a QN8007 to be easy buy and get? on ebay maybe? or aliexpres¿
Great video. Though it's hard to get the model numbers of some of them from the pictures. Also, I think some of these transmitters will not come back on after a power failure (someone has to push the power button to turn it back on) which is a no-go for some applications, yet few of them mention whether they do or not.
Phase lock loop. PLL for people that dont know VCO voltage control oscillator. What about stereo encoder. .? Guess its included.
Can you tell us more about the Silicon Labs ICs?
I own a Si4713 breakout board (controlled by an arduino) and there is much RF noise on the band.
The RF noise is really bad. Don't amp it up. Sound quality was also "digital" compressed sounding. Not sure if I just had a bad setting. I used the Adafruit board to test it.
Any links to the Qn8066 150watt?? Thank you
do you heave qn8007 exciter ? do you run RDS on it?
Hi, do you know the factory website of the ELE transmitters?
Great video.
Do you know what chip is used in the fmuser fu 25A transmitter.
It's either BH1414K or 1415F. If I had to wager, I'd say it's the 1414K.
Found this video after purchase and looks like I got lucky, from the images it looks like the board I have coming is the one in the bottom right at 15:08 It will be here in a day or two so will be able to see for sure what chip it has. I already have a 45w amp so plan to run the main transmitter at 1w rather than 15w and run it through the amp but also have the option of changing the output transistor on the amp to one that will do 60w for less than £5 which is no big deal for me as I soldered the amp from a kit.
Have you seen an STC chip labeled "11F02E"? Other numbers
on the chip are "35I-S0P20" and "1950H10S02.XA".
I believe STC chips are all microcontrollers; it's not the FM chip you're looking at.
@@spectra-man interesting. It looks like the model I'm looking at (supposedly a .1/.5W "low power" one) has a shield over the RF portion, so I can't see the actual FM tx chip.
You did a very good in depth reverse engineering job I’m a old ham guy that has gone rouge LOL yes the eBay ones stay away from. We have a Camel RF from a guy in California that imported the Warner style transmitters puts better parts in that are known to give problems and tests for hours on a dummy load before shipping them out we have the 150 watt rack unit been running it for close to 10 years with no problems and is clean FM audio and does not drift ! The site has disappeared that we got it from was about $1200.00 back then . Do a spot on antennas we have about the last dominator from Norwalk electronics before they went out of business . It’s. .94 wave .
Did you know that there is st-7c that is 3.0 version. Maybe it is better than st-7c 2.0 version. If know what is difference between them please advice.the chip is stc 12c2052
@Spectraman Spectraman , At 7:36 you mention the transmitter that I have, the SD card one 7watt pll. So I've built it a few years ago and it didn't want to work properly at all, the greatest distance transmission I could get was like 300 meters. As I was just a kid I got bored with it, tossed it away at my grandma's. 6 years later now I found it by accident, and went all Jerry Reed Amos Moses on it, disassembled the whole thing, and cleared the connection points because solder wouldn't stick to them AT ALL, and after re soldering, the thing decided to give life, and work properly without overheating for the first time, and I made a big proper dipole antenna in hope it would work better this time, I calculated the antenna in that android app, made the thing out of two metal broom pipes that were hollow 22mm diameter thin metal pipes. And I put it at the top of my rooftop, and my house is like really tall and on the top of a MOUNTAIN. Fired the thing up, went for a test drive, and what I got was 800 meters (half a mile) of clear signal, and all else was just cutting out and nothing after 1 mile *approx 1,6 km*. I am still very dissapointed, because people claim that you can get 6 miles with that thing if your antenna is at a height, and my antenna is not only high, but, really high up, at full power this is my result. TERRIBLE. Also i use expensive coax tv cable about 3 meters long for the transmitter output. (i think that the cable is 75 ohm, or it says on it I think). SO, there could be more things involved, I use 13 volt 1 amp power supply, is it too weak? Is my transmitter too close to the antenna? Too much feedback power? Bad antenna? Bad cable? PLEASE HELP IF YOU CAN, or everyone, thanks in advance, means much to me, i cannot describe how much.
It's hard to give a definite answer without more equipment. You really should get an SWR/power meter. A used one can be very cheap on ebay. That way you can actually see what it's doing. Do you have a power supply with an amperage readout?
Maybe when you were a kid you didn't make the proper antenna and blew the transistor? Does the heatsink/transistor get warm?
The 1A power supply might be OK, but it's right at the limit. These small 12V transmitters aren't very efficient (often a little less than 50%) meaning that power supply may not be enough. 2A would be plenty though.
When I first started, I thought I could get away with just transmitter, antenna, and power supply, but in the long run you will need things like this cause it's like driving blind and asking why you crashed.
@@spectra-man Yeah I need the SWR. You made a fair point, the current meter pops over 1A, so I found a big 12V ac transformer capable of 5A, made a rectifier, filtered it with capacitors, and it's capable of just under 5 amps, however, when I connected the transmitter, the reading that I got was 0,63 A. Way less than my table 1A variable PS set at 13V which reads over 1A current surge.
@@spectra-man The heatsink is always warm, sometimes it gets a little hot, but then the PC homemade temperature reading fan kicks in and cools it down, i made a beautiful alu case for it btw.
@@guitarjoe4379 I don't know. All I can say is the mosfet is probably damaged.
@@spectra-man While thinking about it now, I forgot to tell you an important detail, I was transmitting over a taken frequency on accident, a local radio station that has a tower about 15 km from me... could it be the cause of low range?
Thanks. Great video with many good information.
Just add a low-pass LC filter to the output to kill harmonics.
Ehh spectraman!! Thank you so much again for your videos!! I have a couple of these chinese xmitters but I dint recall what chips are in them but lol.....I'm still rockin a bw warehouse xmitter/exciter that I built as a kit about 25 years ago!! I can get approx 6-8kms with a home made copper pipe slim Jim! I recently picked up a warnerrf fm150a but it has issues. I replaced the roasted final but now it hunts the rf power output after 30 seconds of running. Im gonna try and borrow a thermal camera to hopefully see what is failing. It seems as there is rf getting in the b+ because voltage spikes up n down on the + rail when it starts hunting......odd huh?
Is it safe to feed the Pll/vco kit transmitters like you showed an mpx signal? Or are they already set to 50uS?
If it's really pll/vco, then you can find a way. Can't feed mpx on qn8066.
good info but what is the original transmitter from and where can get one ?
Original? Which original? Almost all of these transmitters are best to find on aliexpress. Just search "X" watt fm transmitter and look for the same picture (XW). Replace X with watts.
it is possible to set the FM frequency with a digital circuit such as MCU, I mean digitally change the variables of LC parameters
Yes, in theory, you could connect an MCU to control it. It would be hard to get it connected to the traces, but it's possible. When you say LC parameters, I assume you mean to control the tuning circuit. That would be almost impossible.
Looking for advice....was using Si4713 adafruit for my Holiday Light Show but am unhappy with audio quality of FM transmission.....looking for an alternative with better quality audio but would like to retain RDS capability.....most people in holiday light show community use Signstek ST-05B but there is no RDS capability with that unit.....Also it lacks an MPX input ......maybe a modification to allow MPX input?......Then use a separate encoder for stereo and rds?......Any suggestions? Thank you 😊
Well, you can get better audio quality with an ELE or QN80xx transmitter, but none of the cheap transmitters have RDS. ELE says it does, but doesn't. Your only option is to go for a more expensive transmitter like PCS electronics if you need RDS and MPX.
If you got a BH1414K transmitter, you can hack in RDS, but you need some soldering and electronics skills. If you have it, then you can search darkliferadio.proboards.com for the BH chip hack.
@@spectra-man thanks for the reply.....I have searched the forum and I have not been able to locate that BH chip hack post you reference ....could you maybe send a link to it or be more specific on where to look?....thank you
You know what? I decided I would rather have a good transmitter than RDS. It was nice to have RDS but not completely necessary so I ordered one of the 8066 7w transmitters with the SDcard slot...the blue one from aliexpress for $25! Now I just have to find a box for it or 3D print something😊😎
Was thinking.....what are the odds that the screen on this module is controlling the qn8066 chip with i2c? If it is couldn’t I hook it up to my Raspberry Pi just like my Si4713 was and control it like that? Maybe rewrite the plugin to adjust for programming code of the qn8066 and get it to do RDS also? Data sheet says it is capable of RDS transmission🤔. Just a thought.....any feedback?
@@iamwally Sorry for delay. Yes, you could theoretically do it, but you'd have to break the connections on the PCB and solder connectors to the PI. Also, it uses a pretty complicated init code. The RDS is very limited. It won't let you display long stuff like song name AFAIK. 7W is plenty of power - it will go too far :)
Thanks for this video. Can you recommend a portable FM transmitter that would be good for 1km vehicle to vehicle transmission in a busy city? Sonic quality highest possible. 12 volts or lower is a bonus.
A question for all of you: Is it forcing your quality to 480p? Remember to change to 720p.
It's 720p by default on me and android phone....
I got it at 720 on auto
I realy appreciate your work. I have seen all your videos and they are useful. Here I must give some clarification. By the data sheet, regarding the spectral spurs there are no significant difference between BH 1414K and QN 8007. But QN is slightly improoved. This Made in China transmitters up to 30 Watts RF Power are not EXCITTERS. They are quite good as LP FM standalone transmitter. No further amplification !!! Soundwise, BH 1414K is very, very good. But, to achieve good (professional radio station) sound, it demands a lot of knowledge and additional equipment. 31 band equalizer, at least one compressor/limiter device, this is if you want to make program by studio connected to audio input of transmitter. If you want to air USB device recording, you must process all sound recordings by special sound filter curve and compressing/limiting . This demands some knowledge with experience. If you have done this process properly, your China FM Transmitter will sound as good or even better than Professional FM Radio station.
In my early youth (mid seventies) there was great revolution by Made in Japan "HI-FI" eqiupment. People liked more sound of FM Stereo radio stations (recorded on cassete decks) than turntable sound. So they considered that FM Stereo is Hi-FI (and turntable not). The truth is opposite. FM Stereo is very Low FIdeliti, but sticky to the ears. That comes from processing sound before FM Stereo transmitter. The trickyness comes from the fact FM Stereo sound consists of 4 elements. Only one L+R is in the original human hearing sound range. There is 19 kHz pilot tone we can not hear, but this sound runnes stereo decoding process combining L+R and L-R, R-L signals which are in the range we can not hear. This facts are main reason why sound before modulation in transmitter must be processed. And additionar reason is "loudness", for the listener who are using low grade radios. With small narrow range speakers, different bad acoustic enviroments, but it is demanded in all this occasions sound od FM Stereo radio station must be attractive,....
You can't rely on the datasheets to always give accurate info for noise on these chips cause they aren't meant for real transmitters. I think QN8007 sounds better than any BH chip, but it has more phase noise. 1414K has less phase noise, but it has a porcupine around the carrier from no filtering the MPX internally. Overall, I think 8007 is better.
I don't use most of these transmitters. I have PCS electronics and BW broadcast TXs. I just make this video for curiosity and for people who want to buy a cheaper transmitter.
@@spectra-man Thank you for the answer. I have for the years PCS transmitter intented to be a excitter. I tested two Made in China LP FM stereo transmitters branded as "Niorfnio". One is 15 W (mesuring shows 19 W) and 25W measuring shows 30 W (even burned 25 W rated dummy load). And , both have problems with spurious emisions when output power setting is low. But soundwise they are great. Of course after the processing the sound. I was the owner of licenced radio station, so I like more XLR ballanced audio inputs, they can not be interferred with RF or lenght of audio cable. I prefer stereo coders separate from PLL. And setting the output power via trimmer potenciometer. But thats pricy professional style of transmitter (good filtering the spurious and harmonics, 70 dB or better). For intented use as backup or even LP FM transmitters (educational, community or RSL,..Radio Stations.) Chinese transmitters are not that bad if are used by qualified persones. Using antenna VNA and spectrum analisers are must for qood setting of this transmitters, feeder cable and antennas. Best regards.
@@jazzforever4631 wow. I like how you broke this down. I have a question if you don't mind. I have a 150watt and I don't understand what the external modulation feature does. It goes from mute all the way up to 15db but I don't understand its function or purpose. Can you help with and explanation? Also, mine is a 5.0 version and as far as audio im using XLR Balanced inputs and audio is compressed before it hits the transmitter and it sounds superb. My input volume is set at -1.0 db which is strange but other than that and an internal error of some sort its still working.
@@DjSmoothNY Well Rohm BH 1414 and similar are designed for micro power use. Mostly MP3 players for car radios having no SD or USB. In another word they have a lot "dirty artifacts" regarding stereo multiplex. So if you amplify their signal, you can hear harmonics all over FM spectrum. Especially if they have LCD or OLED display. The harmonics and other bad artifacts are lower when 15W and 25W transmitters are running 50% or more power. So I say as standalone LP FM transmitters they are quite O.K. But as excitter for the further RF amplification, Quintech based 1,5W , 7W, 15 W. Are significantly better as they have more MPX spectral clarity and 5 dB lower harmonics.
The BH1414 single ic awful, its worse than the 8027 the spurs can be managed, and that 30 Watt tx u showed as being the better, has big issues, you need to set the power to 30watts max, else its splatters the band, I found you can drop the power down by reducing the dc supply, works fine, but its unstable at full power, i run the thing for a few hours only to find it suddenly splatters the band with large spurs everywhere. All those medium powered ebay transmitter are awful, I got 15w module that keeps drifting out of pll slightly and then suddenly corrects every few seconds and makes a pop sound in the audio, just crap, spectrum was not that clean either. You wonder what the guy was thinking who designed these and put them on the market.
I have bought an ELE EL-15s in 7 W version and can verify that the near spectrum is very good! BUT can also tell you that second harmonic suppression is extremely bad! At full power at 88 MHz it is 22 dB down, at 1W -14 dB and at 0.3W (lowest power) it is only -9 dB. Second harmonic is thus fairly constant around 15-16 dBm (30-40 mW) regardless of output power, which is at least 50 db worse than permitted in the EU and cannot be used without an external LP filter. Another disappointment is the very strange AGC function on the AF input which cannot be switched off.
I would be interested in a 15 w cost ? Thanks
I had the same display issue on my broadcast warehouse kit many years ago. The guys sent me a new pic for it and it's still working great some 20 or so years later!!
Yeah, it could have been just defective.
@@spectra-man yes. It was either defective or the firmware wasnt loaded on it. It makes me feel old when I look at their website now lol
Hey Spectraman, I have an nrg pro 4 but to right side of the transmission it's 75khz but to the left it's like 85 khz. What should I do?
Hi, great vid...I have the cze-7c.
Can you recommend an affordable fm transmitter.
ELE EL-15S
Excellent video !!!
Thank you, for the explanation.
A lot of information from you! TNX
I have some chinese fm tx...... the CZE-01B Czerf Pll Stereo Fm-tx Mono Radio Broadcast Station 0-1W is crap.....produce mirrors on much frequencys. The other 1 is like you described St 7c 1W/7W Fm Stereo Radio-tx. Last one CZE T251 .
73 de PA3GEO Robert
Your videos are very good. I have a question 🤔 What is external modulation on these transmitters and what does it do? I have one with this feature but I don't really understand its purpose.
Hmm. Do you mean MPX input? That's basically the same thing as external modulation. It's for if you want to hook up an FM audio processor. Most of the cheap transmitters don't have it, only the more expensive ones. It's good to have cause you can make your station sound very pro. You could try using stereotool with it cause most FM audio processors are overpriced. If you do use stereotool, it's a bit more complicated to set up though. You need to send ur mixer into the comp's line input, that goes through the stereotool software and then that goes out to the MPX. You need a studio level sound card. Then you'd need a second sound card to hook the comp up to the mixer cause both in and out already used by stereotool. It's cheaper, but as you can see, it's kind of annoying and complicated, so if you can afford an audio processor, it will be much better.
@@spectra-manThe thing is, I really don't know if its MPX because it doesn't say that in the settings but I'm sure your correct. I've tried stereo tool and its so complicated to hook up. I had it working once already but found that the presets were horrible. To tin can sounding for me. Not to mention they want 600 usd for the full version. I may as well buy an external unit for that amount.
@@DjSmoothNY Message the manufacturer just to be sure. I just bought one of these optimod processors. You might be interested: prostudioconnection.com/collections/orban-optimod-processors/products/orban-optimod-pc1100-v2-win10-compatible-on-air-processing-pci-card-xlr-w-cables-refurbished
Have not tested it yet, but I will make a video on it in the future. It's the best value for money I could find. All the other good processors are $1000+. And optimod has been known in the industry as the best processor. You need to make sure your PC has a PCI slot in it.
Optimod pc1100 won't be better than stereotool. You can run the station with only 1 computer with stereotool using the soundcard output. Remember to calibrate the Low frequency tilt. If you want external processing you will need a modulation monitor too
I've bought FM transmitter with QN8066 from Ali. Sound quality is very good. With good audio processing I can professional sound.
good day to you suir idol, i would like to ask if what kind or a halfwave GP antenna is suitable for chinese fm transmitters sir idol... that my question sir idol
I cant find the good ones on amazon / ebay, where I live that are the only options to buy things, could you leave a link? Thanks!
You will find them on aliexpress. From there you can order to pretty much any country. Aliexpress has more options than ebay or amazon. Amazon only has the BH1415F.
I can't give a link cause I don't know which one you are looking for, but it won't be hard for you to find. Search 7W FM stereo PLL or 30W, etc.
Hi, thanks for your informative video. I have niorfnio t15b, every time i go on air, it can be heard from other stations than the one selected. How can you help me with this issue.
It's because the BH chip has a wide signal. You need a better transmitter without BH chip like I said in the video.
But remember, when you put the receiver near the transmitter (EVEN on a very GOOD trans), it still might block other stations. Move farther away.
Thanks for posting this good and informative Video, with all it´s Informations. I also have a transmitter here, prolly using the 1415F chip, stating it puts out .5Watts. Occasionly (really rare) use it for some private broadcasting, but thinking about it, the last 2-ish years it just stood in my shelf. I´ve checked the harmonics (double, tripple Frequency etc) and it is supressed well enough to make me feel ok using it. The audio quality is not the best. The stereo seperation is by ear quite good, but the bass-sounds don´t sound to good. There seem to be no real "low" frequencies, and the bass that is transmitted just sounds... cheap... hard to describe. I´ve got another transmitter that has no volume / mic controls on front. Just a frequency up / down key and the display (the on off key is at the back). Also a .5Watt version bc I think for some "hobby neighbour" broadcast this is far more than enough. However, this transmitter (in a silver metal case) puts out far more power than the CZE one (I think the other .5Watt Tx is a CZE, its the same housing as your CZE7 Watt-er but with .5Watts only)... anyhow, the sound quality is excellent to the ear, and also the harmonics are well supressed. Unfortunately it broke by itself... I used it with original antenna (which I know, may not have had the best SWR, I didn´t measure it...), and what happens now, is that it cycles the power. So it would transmitt with full .5W for like 2 seconds, then go to like ...1/2mW (that´s how the range is) then go back to .5Watt aggain... maybe it´s lose solder connection which bends back and forward as the final transistor heats up? Whatever. ... What do you think of the BH1417 Chip? The one with some fixed Frequencies either at the low FM band or the top FM band... Have you ever heared of the "Veronica" Transmitters? They claim to be professional transmitters. They have seperated VCO / PLL (and PLL is lots of ICs not a single IC) but they run the oscillator at half frequency for better frequency stability. In a forum people tested these, and said that they produce lots of harmonics or... not so good signal bc the doubler circuit may not be perfect. I do have one of these myself (1Watt) but in all the years I own it, I just plugged it in a few times mostly for testing... It´s more like a "novelty" item to have... because it has lots of memories of my childhood for me. You could get / test one of these? What do you think of the combination(s) used in wirless speakers or headphones ... the ones that use the old BA1404 and use it´s internal oscillator, but "steer" it with an external PLL? There´s a company here selling a transmitter based on the SI74 something?? Chip... it is said, that the signal quality is ok for super weak output power, but it´s very "broad" so better not amplify it. Also have one of these transmitters - to me the audio sounds excellent, nearly as good as a professional station (others think that too) but my Tx has issues with its signals because it can for example not log in at Frequencies over 100MHz... Just a "few cents" from me. Good Vids you make there :)
Hi Stefan. I used to watch your electronics vids, but I just forgot about your channel. You also helped me with a simple AM schematic many years ago :) You seem to have a better understanding of general electronics than me. That's a lot, but here we go...
Yes, it is true that the BH series of chips have bass distortion. The BH1417 is said to have a slightly better audio quality than the BH1415 due to a better stereo generator, but it still uses the same switching type design. The BA1404 is also marginally better than the 1415, but haven't tried it personally and it lacks the PLL circuit. I think maybe adding your own external PLL could be good. Yes, I've heard of veronica. I have an AAREF clone of the board (1W). The signal spectrum is very clean and the audio quality is great. But today, it's unnecessary to have so many components and it was cloned by a guy with not much RF knowledge. There are some devices from analog devices which could really simplify the design. It's a shame they only come in tiny packages like QFN. But I think if you want to do hand built, the best option would be your own VCO + MC145170 in DIP package (like the radiomaster). You could even get one of those self contained mini-circuits VCOs (but they are kind of expensive and not sure if still available). That's what stefan dunifer did on his free radio berkeley transmitter. You also SHOULD REALLY BE AWARE of the PKB and RDVV:
www.amateurradioshop.nl/webshop/bouwkits/fm-broadcast/
They have an EXCELLENT VCO with many diodes. You can see they have a 6W sender kit and just a PLL kit. Maybe the PLL could work with BA1404.
Hello Spectraman, many thanks for your video, very informative.
Do you know if the QN8007 is still on production? If so, where can we buy it.
Best regards.
I don't know, but you can still get it I think on alibaba and a few on ebay. If you want to make your own transmitter with it, just know that it's very hard to solder properly. I spent a lot of time just trying to solder it. I hope you just use it for yourself though cause I might be selling my transmitter and I was kind enough to tell everyone the secrets, so I'd appreciate it if you don't steal the idea. It took me a very long time to find the best chip cause most of them don't tell you how clean the signal is; you have to test it yourself. If you sell only to your country (not US) like Italy or whatever, then I don't care.
@@spectra-man Hello, I got a few QN8007B from ebay. Made a small test board with a buffer-follower (S9018) and a amplifier for +20dBm output (BFG135). Very pleased with the results! No the same as a discrete VCO with PLL, but quite clean compared to the Si4713 that I have tested before. Audio quality is not perfect, but very good, I found that in Mono the audio sounds better. Still have not tried the RDS.
The only thing I have not solved is some spurs that appear from around 107 Mhz and up, very noticeable on 107.9 Mhz, they are at +-450 and +-900 Khz. On the rest of the band all is clear as far as I can see on my TinySA. Will try to get a real SA to check further. I promise not to sell this in the USA if I make a full transmitter , I'm very far away from there!
Again many thanks for sharing the information on the QN8007, take care
@@diegoccs I don't think I tested above 107 on the spectrum analyzer (only audio test). I use low band, so I only checked that. I can test it and let you know. Maybe make a video.
A design with MMIC fed into RQA0009 can make a few watts in two stages. By buffer follower you mean an attenuator to reduce noise in the chip? If not, that is one thing that was recommend to me by PCS. You amplify it more than necessary, put an attenuator and then amp it more. It will reduce potential reactions from the amplifier inside the chip causing noise.
@@diegoccs Also let me know if you test I2S digital audio input on it. You can probably find a module for that on ebay too. I want to know if it's working with the QN8007. It says it has this feature of digital input.
@@spectra-man Hello Spectraman, I sent you an email with the measurements from my QN8007 tests,
Hope you find it useful!
Awesome video idea, I really haven't seen another channel that does stuff like this. What do you think of building an fm transmitter from an FPGA + DAC?
Thank you :)
That might be good, but I don't know how to program FPGA. I program only in C type languages. I don't think it would be any better than DDS + DSP though. If you were trying to make some custom signal, then it could be better, but for normal FM broadcast, I don't see an advantage. SDR would be very similar I would think. I do have some experience with that. LimeSDR is still not here, but at some point I will be using that.
am interested in buying your transmitter 25w ,30 or 50 which of them will i get from u ?
I don't sell my transmitter cause there was not enough interest and many parts have to be hand built due to obscurity of parts.
@@spectra-man so where can i get the good and how will i know this is good ?
@@yungman3033 aliexpress
I have the niorfnio 15watt.. been on air about 3 years...still sounds good, and no FCC warnings yet.. idk. I dont think they give a rats ass unless your on top a comercial station and they request that the fcc " fix " the issue with you transmitting on top of them..
Ευχαριστώ γλύτωσα από περιπέτειες Spectraman
As i didn't Test yet >1. QN8007
and 2. QN8066 < ..... The BH1414K is the Best IC, compared with the others IC's ((except 1. QN8007
and 2. QN8066 As i didn't Test yet )) that i Used and Tested......BH1414K has very good Audio Modulation but it has a problem in Carrier S/N. (has a noticable"hiss" noise in carrier than some others IC's). BH1414K DataSheet declaires that it has a S/N ratio of -55dB Min / -68dB Normal, 🤔 but i think the Normal S/N is -55dB for this IC....and this value is not good for me. 😠 This S/N carrier problem of course affects, and increase the "hiss" noise on carrier when use it in Stereo Mode. It's not such a serious problem, but it is quite noticeable if we are seriously interesting about the best Fm TX IC in market. Also, I take very seriously the Spurious/Harmonics dBc/dB values and the BH1414K is the best in that case...Unfortunately...😢 the carrier S/N ("hiss") problem is quite serious for me, so my rating for BH1414K IC is 8/10...and still the best than the others IC's that i tested. If BH1414K it doesn't had the S/N carrier problem my rating it will be absolutely.... 10/10 !!!!🙂
Play this video at 1.25x speed
I ran it at 1.5
1.5 team
Bh1417f chip any good?
Who uses these transmitters? Aren't they highly illegal. I doubt if they would pass the FCC requirements for FM Licensed LPFM
I'm assuming they must be used in China. 100 watts on FM? Surely you aren't talking about broadcast. I bet the pirate broadcasters
in Manchester UK (there are lots of them), causing OpCom some serious headaches.
Kt0803 is not a bad one.it has a well defined digital interface . When the i2c programming done very well it has awesome output like qn8007 and bh1415. so please try to program very well in c or cpp with respect to the datasheet
Are you sure? Have you seen the output on a spectrum analyzer? It looks like a tit :)
Do you mean if you program it differently, it won't look like a tit?
@@spectra-man 😁😂😂😂
Doe any one know of the best studio to link 1 radio for fm broadcast transmitter
A lot of great information..But for those who don't want the FCC knocking on our door.. How about reviewing Part 15 FCC Certified FM transmitters in the future.. Great information for church, drive-in movie theatres,etc. Thanks.
The FCC is complaint driven, unless you're really interfering with another licensed station or not minding your own business, I doubt they will waste time and money to come hunt down a 15Watt broadcaster.
Wow I learned so much.
Nice explanation!
What about the Niorfnio t15b?
Don't you see it? It's in the BH1415F category. It's the gold model in there, but silver is the same thing. I don't have one, but the supplier told me it's BH chip. So not 100% sure, but like 90%.
Hi, thanks for your informative video. I have niorfnio t15b, every time i go on air, it can be heard from other stations than the one selected. How can you help me with this issue.
Ive got the unassembled 7w one 15:55 (Quintic) the 3.5mm jack doesnt work. It produces high-ptched beep noises when I hooked up my phone or PC to rebroadcast DAB-only stations which is weird but good thing: no harmonics. I would have to use the built-in SDcard slot. Also, the antenna port doesnt work (I tried copper wire connected to the pin since I dont have a 50 ohm antenna. The distance is just 6 feet away, dissappointed. 7W is a lie. UPDATE: The jack works but the sound is very low (like BBC Radio 3). Youll need a receiver with a really loud speakers! I tried turning on compressor and it doesnt work.
Probably something wrong with the kit. I found that it's not usually a good idea to buy kits from China, only the pre-made versions are good. When you get a kit, the Chinese put used/broken components in there and sometimes they forget stuff. Better to get pre-made cause it's not very expensive. I had this happen to me a few times with an MRF186 amplifier kit.
And BTW, I can't respond to all your comments cause youtube is not giving me the reply box for them. Don't know why.
UPDATE: The port I plugged was a green jack which is a microphone Jack anyways. The transmitter now works but I'm waiting for a 50 ohm antenna. I got 2-inch distance from a old used wires connected to a pin which is weird maybe it is not callibrated. Luckily the tranmitter didn't blow up but when I moved the wire it stopped transmitting until I replug the cable.
@@spectra-man how do I set the 7W transmitter to 0.5 watt? I dont get what the power value 300 means.
@@bioskahabinivous9906 Don't use it without a proper antenna! The 7W transistor might blow out. You might want to get a couple extras just in case. I don't think they are too expensive. Then you can play around with it.
This is informative, but showing a unit, circling it and saying "this one" doesn't tell us what model it is. I'd like to see a list of what each one actually is, otherwise it's just guesswork on the viewer end.
See, the problem is that many of these transmitters are model-less and brand-less. I think I said in the video all the models of the ones that actually have model numbers.
So in order to find these transmitters, you just need to look on aliexpress or ebay under generic search terms.
@@spectra-man We both know that a single design in these Chinese products is duplicated many times over into similar-looking products, some of which vary widely in quality, so matching a fuzzy image is literally a shot in the dark. What about for instance the one at 26:10? You say you own it? If the images were sharper we could read them, and *some* of them we can but otherwise it seems unnecessary guesswork, and I see several others already made the same point.
I do recognize the one at upper left 19"22 as a *CZE-15B* if that helps anyone. If that's the CZE-T251 to its right there seems to be conflicting info on that one, as Eddy Bergman says the 251 uses the BH1415F, while the 15B does use the 1414 as indicated. You've got the 251 using the 1414. I don't know which is correct, just looking for reliable info before making a(nother) purchase.
@@notvalidcharacters im in the same boat, did u gather any more info of what is what as of now?
@@DJTKarlsson Not really. I did end up picking up one of the ELE units, and I have to say it's disappointing. Stable, but doesn't really sound great. And I'm comparing to much cheaper stuff.
What if my Transmitter is only pll not vco?
Not possible. If it's PLL, it has to be VCO, but if it's VCO it doesn't have to be PLL.
@@spectra-man oh, okay. Is there a way to just tell by looking at it?
How good or bad is QN8006 ?
Do you mean the QN8066 or QN8006? Cause the QN8066 is very common and pretty good for a single chip design, but not PLL/VCO quality. The QN8006 I believe is slightly better because it's basically just the QN8007 with a receiver built into it as well.
@@spectra-man I bought a PLL board that has this QN8006 chip (not the QN8066). I didn't find more tests with this chip on the internet, so I decided to ask the question for you. Thanks for your attention!
@@thiagolaj Would you mind telling me what PLL board it is? I've never seen an 8006 in the wild.
What about FMUser FU-25A?
It's the same as the CZH-T251 I showed, so very likely it's a BH1414K.
@@spectra-man ok cool I open mine and have a look
Looks like there's already two transmitters I missed. If you go to my site: dosaidsoft.com/wp/
Scroll down until the end of the right side column and click the donate button and then I will buy more of these transmitters to review. Thanks!
@Spectraman Spectraman , At 7:36 you mention the transmitter that I have, the SD card one 7watt pll. So I've built it a few years ago and it didn't want to work properly at all, the greatest distance transmission I could get was like 300 meters. As I was just a kid I got bored with it, tossed it away at my grandma's. 6 years later now I found it by accident, and went all Jerry Reed Amos Moses on it, disassembled the whole thing, and cleared the connection points because solder wouldn't stick to them AT ALL, and after re soldering, the thing decided to give life, and work properly without overheating for the first time, and I made a big proper dipole antenna in hope it would work better this time, I calculated the antenna in that android app, made the thing out of two metal broom pipes that were hollow 22mm diameter thin metal pipes. And I put it at the top of my rooftop, and my house is like really tall and on the top of a MOUNTAIN. Fired the thing up, went for a test drive, and what I got was 800 meters (half a mile) of clear signal, and all else was just cutting out and nothing after 1 mile *approx 1,6 km*. I am still very dissapointed, because people claim that you can get 6 miles with that thing if your antenna is at a height, and my antenna is not only high, but, really high up, at full power this is my result. TERRIBLE. Also i use expensive coax tv cable about 3 meters long for the transmitter output. (i think that the cable is 75 ohm, or it says on it I think). SO, there could be more things involved, I use 13 volt 1 amp power supply, is it too weak? Is my transmitter too close to the antenna? Too much feedback power? Bad antenna? Bad cable? PLEASE HELP IF YOU CAN, or everyone, thanks in advance, means much to me, i cannot describe how much.
Great video
Wow. Thank you. So really the 8015 from pcs electronics is best because why?
PCS is a PLL/VCO so it works as a professional transmitter. These work like the little transmitters for a car, but amped up.
It's not #1 though. I'd say NRG PLL PRO or RadioMaster is the best you can buy, but they are much more expensive and PCS is good enough you won't notice any difference between them.
@@spectra-man Okay, because I just wanna make sure eim buying something that's worth it. I'm currently rocking a 15 watt bh1415f
@@antonio1681 Yeah, it's worth it. It might only sound a little better, but the difference is in what you can't hear. And PCS is clean enough for amps unlike BH chip.
@@spectra-man okay great! I also make videos on the Transmitters and tech at ruclips.net/user/AntonioCasciato
@@spectra-man www.ebay.com/itm/150W-76M-108MHz-FM-Stereo-Transmitter-RF-Power-Amplifier-Radio-Station-Ham-/122824900269?_trksid=p2349624.m46890.l49292
Is this any better than the pcs electronics?
Also, can this be changed to 75uS?
I have a CZE 7C with a BH1415F, and it distorts too much in the bass frequencies. I have to adjust the processor to the point where I lose the bass in the music I transmit to avoid exceeding modulation.
Also, which one of these transmitters has a stereo pilot that doesn't overmodulate the final carrier? In the CZE 7C, the stereo pilot reaches 24% modulation, and I can't lower it.
Which one do you recommend then, one that doesn't have distortion and has a stereo pilot of at least 10%?
Greetings, your video was very helpful.
Stop using cze transmitters. Their audio circuit is complete garbage. Try a DDS transmitter with external audio processing like BreakawayOne
Radio master is so overvalued and rumors is not good about clear signal..
How to get good one brother
28:33 LoL