MiNiPA50 HF PA with Icom IC-705: compatibility, real power output, temperature test, heatsink mod.
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- Опубликовано: 11 июл 2022
- What’s up everybody! It’s a long video this time, but you can split your watching time into two slots! The first part is devoted to discuss this little MiNiPA50 HF linear amplifier, it’s pro’s and con’s in relation with usage together with the Icom IC-705 transceiver, counter-electromotive force and heatsink mod I made for my MiNiPA50. Second part of the video is all about practical power output of this PA vs the input from the transceiver vs supply voltage. I find out that 18V of power supply with 2.5W drive from the transceiver is the best option. You find out why!
In this video, I also briefly mention another Chinese HF power amplifier, MX-P50M, for comparison purposes. That PA is not readily compatible with the IC-705, so I provide a link in the video to another video by Kevin “The Old Tech Guy”, KB9RLW for possible mods. I also stress that these two amps are not the same in different package, they are different in schematic diagram design.
Here is my affiliate links to these two interesting ham radio products (I might earn a small commission if you buy through these links at no extra costs for you).
MiNiPA50 HF PA
amzn.to/3Pm7avK
MX-P50M
amzn.to/3v3TjT9
Thanks for watching and subscribing! This channel only grows and survives thanks to you!
73! Linas LY2H 
Хобби
Excellent! Rarely do I see such clear and complete explanations. I'm strictly QRP but I enjoy seeing discussions of higher power equipment too. Keep up the good work.
72,
David VE7EZM and AF7BZ
Great video. First person in the planet who actually reads manuals
This was a perfect video for me. Just thinking about some amplifiers for my IC-705 too. Great job. Western Canada is under a heat wave too. +32 C here to day. VE6KBI Dana.
Excellent video. Thanks!
Good morning, very good video. Thank you for your informativo. 👍😀
Excellent and thorough test. N9EEE
mni tnx for this video!
Excellent quality modifications and testing.
Can you install a small shallow fan for the resistors at maybe half speed?... just enough to keep them at a safe level and not be loud?
Thanks for watching! A tiny fan would probably be a good idea, just as you say- it should be small and quiet . I need to look into that! Thanks for a tip!
73! Linas LY2H
Very good and informative presentation. Really enjoyed it! Wish you had increased the power input to the amplifier to at least the 5 watt level at 18V as the MRF-186 is a very rugged transistor and it would have been well within it's ratings. What might be interesting would be to measure efficiency at different voltages right up to it's full rating. I suspect you might find it would actually be more efficient at the higher levels and I suspect if the other PA components would handle it, you could achieve twice the power.
Also, would have liked a little more information on your PTT method as some of these amplifiers have RF Sensing. Did you use the "Send" output on IC=705 and if so, any difficulty? Many seem to find it will not activate an external amplifier.. 73 and thanks
Thank you very much Randy! Yes, I did try 5W ( and not only:)) IN at 18V (and not only :)), and the PA was giving out around 60W. Further increase in incoming power made no feasible effect , except that possibly overloading the gates of the transistors :). The transistor itself , by the way, was not getting overheated after the mod on the heatsink, but the 3 big resistors were. These resistors are important to keep the PA entry impedance in place , but they are getting very hot even at the modest duty cycle. I'd like to replace them with the more powerfull ones if I manage to source them out ( they need to be of non-inductive type).
As it comes to the IC-705 SEND port, yes I use this connector as there is no any other on 705 ( like usual ACC port) :). It goes to ground on transmit and it's OK for the radio , as long as current this port has to handle is no more than 200mA. The relay in the PTT line on the PA50 is only drawing some 55mA, so it's OK. It's on 7.23min in the video about this issue. Practical test in the field proved it's OK too ( more on the field test in my other video:
ruclips.net/video/lOmpzDdTt6E/видео.html
Thanks for watching! 73! Linas LY2H
Very informative video as always. I opted to pick up a Yaesu FL-110 amplifier instead of getting one of the PA50's. Now you have me wondering if this older amplifier may have the same fedback issues and be harmful to my IC-705? Guess I will have to do more research before hooking it up. Seems to work well with the FT-818. Thanks again for your videos.
Thank you Raith! And congratulations with an excellent purchase , the FL-110! I wish I had one too! I like this pre-FET, pre-WARC design. As it comes to the work together with the IC-705, I see in the schematics this PA is PTT controled by the RF signal sensor, actually, not the PTT line from the transceiver? I’m not sure there is even a PTT socket anywhere on the box :) If so, then it does not matter , the pecularities of the PTT line in the IC-705. I found an excellent article by a Dutch ham PA0FRI here, hope it could be useful for you , or you have it already may be:
pa0fri.home.xs4all.nl/Lineairs/FL-110/fl110eng.htm
Have fun with it! 73! Linas LY2H
@@Linas_LY2H You are absolutely right. No PTT socket and RF sensing. Thanks for the hyperlink. I will put it into action. I have heard good things about this amplifier and managed to find it in a junk shop for $150 cdn. Looks almost new. It will pull it out and use it with by qrp radios (TruSDX, FT-818, IC750 and the QCX & QDX when they arrive) when a little more power is needed. Your clever insights into radio are greatly appreciated.
Do you think the thermal efficiency would be improved if the black paint on the case inside and outside surfaces were removed ? There is now a similar product called Micro PA50 available from China. Excellent explanation ! Thank you.
Thanks for your comment! I think, these boxes, in most cases, are of anodized aluminum, not painted. As anodization is an electrochemical oxidation process, the surface, actually remains a part of the aluminum mass, not an extra insulating layer of paint. So, I would think, there is not much sense in grinding off the anodized layer for the purpose of better heatsinking. But I'm not major in metals chemistry, so may be other people here would know better :)
I do have and testing the Micro PA50 at the moment, looks and works nice. But it's not the same as Mini PA50. The transistors are different and much more features incl safety protection, are installed. The IRF530 transistors are not designed to work in HF PA applications, so could be problematic , but being very cheap, they are easy to replace. My review on this nice PA is in the pipeline :)
73! Linas LY2H
Interesting video linas, and too much heat is always a worry.
Is it possible to use the unit upside-down, therefore the heatsink is on the top.
Maybe more drilling and some small holes on the top for air to rise.
Good work.73.
Thanks Brian! No, you can't install the heatsink on the top cover , as the PCB is so designed that final transistors have to be fixed to the heatsink from the bottom side. But it's certainly possible to flip the whole PA upside-down when in use ! :) 73! Linas LY2H
Hello LY2H,
Great Video!!! I was wondering if you know if the Micro PA50 has the same diode protection as the mini?
I have the micro paired with the Lab 599 Tx-500. I’ve noticed sometimes there is a spike of swr on the radio to infinity and it comes down but sometimes stays at around 2.5:1 while the amp states 1.3:1 or so? The radio works fine without the amp and the swr is always around 1:1 but I’m getting s9 reports with distortion and voice clipping.
Thank you!!
Thank you Bob! The vendors of the MicroPA-50 do not provide with the schematic diagram motivating that "it is not an open source", so it is hard to say if there is a diode installed you are asking about. Chances are, it is, as this PA is packed full of various safety features, so this simple diode would be the simplest thing to do. But if it is not, not a big deal for me, as I am mostly intend to use it in the automatic mode with the RF-sensed T/R switching, so no PTT cable connection would be employed in my IC-705 ( or any other radio).
As it comes to the SWR anomalies, I have encountered nothing similar so far, but I've only have it since recently so too few of user practice to make any judgements. It seems to me, though, this PA is pretty sensitive to any "RF in the shack" and it's the CMC which may be a cause for the SWR-related abnormalities, so the RF choke is our friend here :). I could tell more after some more intensive use of it. CUL! 73! Linas LY2H
@@Linas_LY2H Thank you very much!!! I guess I am confused as I thought the issue was if the radio didn’t have the diodes while using the rf sensing there would be a problem.
I just figured out what is happening with my SWR issue. I’m using SL259 to BNC Adaptors on the Amp. The connectors on the radio have a lip at the base that is too high causing the adapter to not seat tight. I switched over to cables with pl259 ends and it works perfect now.
Thanks!!
@@Linas_LY2HAlso there actually is a firmware update for the Micro PA50 (Note this is not for the Mini) I have 2.1 firmware and going to leave it unless I can find out what this update does but thought you would want to know about it. www.dropbox.com/sh/8ckmcobxo3pwagd/AADlxpVcmSsz8VQEtS1olmaAa?dl=0
@@Linas_LY2Hwas still noticing some spikes of swr and put a choke on as you suggested. Absolutely all clean now!!
My xiegu g106 is only swinging 1 to 2 watts. Will just 1 watt activate the amplifier? This information would be very helpful. Thanks
Hello JR! You got me curious, so I took some measurements. The values below are for the 13.8V power supply, I’ve measured it on 14.1Mhz and 7.1 Mhz frequencies, from my IC-705 transceiver. So: 0,5W IN=6W OUT on both bands. 1W IN=20W OUT (20m band), 14WOUT (40m band). 1,5WIN=30WOUT (20m), 20WOUT (40m). 2WIN=35WOUT (20m), 30WOUT (40m). At the power supply level of 18V, the output power is actually the same at the input level up to 1.5W, and it reaches up to 40W of output at the 2W input level. The values above 2W input level are well described in the video. Hope, this helps! Good luck with your G-106! (it should deliver more power, may be some tweeking of low pass filters would help, like squeezing/spreading the turns on the toroids?) 73! Linas LY2H
@@Linas_LY2H Thanks so much. Not many people will go out of their way to help someone out. A hundred thank you's... 73's JR.
I have the MicroPA50 and the fan is so lud that I dont really use it. But if i had a heat sink like you have and disconnect the fan, and I am only SSB, I might use it again
Hello Mike, thanks for the comment. Yes, the fan is noisy in MicroPA and clearly needs a fan mod which I’m working on now. As it comes to the heatsink, interestingly enough, it’s much better/larger than the one in MiniPA. The fan, actually is effective, except for the noise :), and helps the whole construction stay compact, which, I think is rather important for the portable user. CUL! 73! Linas LY2H
Hi there. I was very interested in the MiniPA50 and was planning on buying one. But astonished how much they cost to buy in the UK. At one place it is £798 with £17.67 postage. Via Alliexpress its £448 and £10.84 postage. So with only my state pension it's too much money. A 50w SDR transceiver is lower cost. Cheers from old George in the UK 🤔🇬🇧🤠
Hi there. That's insane! I think, I was paying something abt 180EUR some years ( pre-pandemic) ago. If you try to go via the amazon link in the description ( my affiliate links) for the MX-P50 amplifier, the same link opens also the Minipa50 offer at GBP 229. (The first link in the description seems to be broken now. ) 73! Linas LY2H
By the way. This is not a critisim of the Minipa50 and Ly2H's video. I always enjoy his content. Just saying if like kit building and want to save money, you can build a very similar amp.
@@markmeyers7923 Hi Mark I do enjoy building stuff. But in kit form it can work out more expensive. For example today to make a 49 to 1 unun. With Toroid, Connectors, wire, nuts and bolts, Waterproof Box adds up to £24. I have just purchased a ready made unit for £15. Doesnt make sense to me. Every penny counts at the moment especially in the UK.
@@markmeyers7923 Thanks for your comment! I agree, kit building is fun, I do a lot of it. As it comes to the cheap (pricewise) Chinese HF PA kits, they should perform normally, if components, like FETs are not fake etc. :) and low pass filters supplied by the user ( another simple kit). Then it's the same as MX-P50. As it comes to the MiniPa50, it's a bit more sofisticated device with the voltage comparator circuitry in it in order to decode Yaesu band data from the FT-817 trx, wich this PA originaly was created to work in duet with ( and it really works nicely with my old '817). I have heard of no Chinese PA kits being complicated by such a functionality, so far :) 73! Linas LY2H
Transmit relay buffer as recommended in the icom manual?
Hello, as I understand it, the manual recommends to put a diode accross the power contacts of the RX/TX relay in the PA . If you mean the same, then, yes, such a diode is installed in the MiniPA-50. 73! Linas LY2H
@@Linas_LY2H Yes, meant the same, just didn't have the terminologies correct. Good stuff! Thank you!
Another informative video. IC 705 is bringing lot of possibilities to you.
How do you match its reciever with contest rigs such as ts590?. I saw other video where you operated a contest with only 705. Very interesting to see what little rigs can do paired with Juma amp in contests
Keep sharing.. de vu2xe
Thanks for watching! I don't have the TS-590, so can't compare with it. I have fully upgraded Elecraft K3 instead, so it's gotten a bit lower noise floor vs IC-705 and better Dynamic range when coping with strong adjacent signals. I mean, it's my subjective perception, I've been doing no 2 -signals or similar tests with signal generator. But IC-705 is better , IMHO, than my IC-7300 despite being "similar" which they are not :). The receiver on VHF/UHF is very low noise and sensitive, really better than my former FT-897 or IC-706mkII . And yes, running the contest with my Juma PA in the HP category ( though I like QRP more) is just fun! 73! Linas LY2H
@@Linas_LY2H k3 is Fb rig
Nice video! The schematic of the MX-P50M is wrong. Not only the missing flyback diodes, but also the not switched bias voltage are reasons to doubt the schematic. In fact, the MX-P50M is using flyback diodes for the relays incuding those for PTT (placed on the bottom layer) and the bias voltage is also switched on by the PTT. So the modification shown by KB9RLW is not necessary. The PTT is safe and needs under 50mA (considering 2 x 720 Ohm coil resistance parallel) to switch.
Thanks for watching and commenting! As I said in the video, my story is not about MX-P50M because I don't own one :), so I can't judge if the schematic is correct. I thought it is correct as simple Google search produces the one I mentioned , for example the one presented by WB4KDI on QSL net. As it comes to Kevin's KB9RLW mod , I also saw reports of numerous hams who made this mod on their MX-P50M PA's and were happy with the results. It could be that you have some other, unknown to me, incarnation of that PA with all the diodes in place and of different schematics. I'd be glad to see this PA and that schematic diagram for the sake of some possible future videos. Thanks! 73! Linas LY2H
@@Linas_LY2H Thanks for answerng! I agree, you are presenting the MINIPA50 and did it the right way, checking and comparing the schematic with the real device. That's good practice! I don't know where the wrong and incomplete schematic for the MX-P50M is coming from. I have here 2 devices, both v1.3, like the one in Kevin's video and both are "safe" to use. For sure there is nothing wrong doing the mod, but not necessary. 73 de Cyp, DL1CYP.
@@cymo7817 That's good to know, thanks for the info OM! I feel intrigued now to buy one myself and see :) ! 73! Linas LY2H
Sveiki.Norėjau paklausti.Ar verta pirktis Icom ic-705.Noriu kažko universalaus ir nedidelio.Kaip jo kokybė ir jautrumas(kaip imtuvo)?
Dėkui Jum už video.
Sveiki. Ačiū, kad žiūrite. Imtuvo jautrumas, mano manymu, atitinka nurodytą techninėse specifikacijose ir yra pakankamas radijo mėgėjiškiems ryšiams, kam šis aparatas pirmiausiai ir skirtas, taip pat "broadcast" radijo stočių klausymui. "Kokybės" kriterijaus negaliu komentuoti, nes tai subjektyvus, o ne objektyvus rodiklis, priklausomai nuo to, ar esate radijo mėgėjas, kokius tikslus aparatui keliate ir kokia jo panaudojimo sfera jums svarbi. Man, asmeniškai, kokybė yra gera, bet jūsų nuomonė gali būti ir kitokia. Todėl ir patarti, ar verta pirkti, ar ne, negaliu, tai - tik jūsų sprendimas. Sėkmės! 73! Linas LY2H
Dėkui.
73,Timofejus LY7TI
It doesn't seem to be sold anymore
I don’t know, but have just made a random Google search for “miniPA50 amplifier price” and was rewarded with the link to e-Bay (I can’t copy-paste it here) which says it’s available at the price of 169USD plus shipping. So… :) 73! Linas LY2H
Where to buy?
One of the possible links is in the description. 73! Linas LY2H
@@Linas_LY2H unavailable everywhere 😪
@@regularguy519 sorry to hear 🥲
I haven't seen a "real" MRF186 out of China. I would highly recommend not depending upon the values on the Motorola data sheets. Especially SWR and wattage; as evidenced by the 7 or 8 dead "MRF186's" that have found new homes in my garbage within the last year.
Thanks for sharing this down-to-earth experience of yours! Very useful and good to know! 73! Linas LY2H
Excellent and Informative Video 🙏
ThankYou ⚡🙏⚡
Excellent video! Thanks!