Thank you for doing a build of my new antenna kit! For any ham radio clubs out there just wanted to let you know we offer a $5 discount per kit if you want to do a club kit build! 73 from Jonathan Kayne, KM4CFT
Nice little antenna! I like your banana plug idea. End fed antennas seem to be the latest craze and rightfully so. I always hear great signals come from them and it looks like you don't have to go too far off the ground to get a descent signal out. Quick and easy to set up as well. Thanks for showing and 73.
End Fed antennas had bad rap for a long time with stories of RF "in the shack", etc. which probably stemmed from the use of end fed random wires used without proper UNUNs and counterpoises. But a properly tuned EFHW really does work great - super easy to deploy, and works well when setup as a sloper, inverted V or vertical - just keep the feedpoint and end point a foot or more away from ground.
I would love it if you could do these two sanity checks: (1) Please measure the insertion loss of two 49:1 un-uns wired back to back. That is, high impedance side connected to high impedance side. (2) Pease terminate the high impedance side of one un-un with a 2450 non-inductive resistor (2.2k is close enough) and measure the return loss (or VSWR) looking into the 50 ohm port. A nano-VNA would be the instrument to use.
Hi Alan, Nice build with great instructions, especially how to handle the soldering of the enameled wire. Had no doubts on the results. Stay safe. 73 WJ3U
SO DAMN FRUSTRATING! Great video. Learned a lot and plan to buy one of these. But I’m a new ham and have tried many times daily to get picked up the RBN on 40m and NOTHING. There must be a secret handshake or something. Absolutely maddening. But, I sure liked the build and look forward to getting it, building, and using it! Many thanks for posting.
The bands have not been in good shape the past few days. Also, the RBN isn’t great about picking up calls if the timing of your code isn’t perfect (which is why I used the keyer).
It's simply a 100pF 1kV capacitor. I find that as long as they are decent quality then they work fine. Any variation in capacitance would be sorted out when you prune the wire for the antenna
@@JonathanKayne @aktik6000 One interesting thing here is, most people specify a 1kV rated capacitor for this application. This really isn't necessary since the capacitor is on the low-voltage side of the transformer. Any decent RF-type of 100pf cap will do (ceramic NP0, silver-mica, etc.).
Hello again. So, as I continue to learn as much as I can about the radio hobby and the field in general, I always come back to Baluns. I pretty much get the why and how, my new question is do the varying sizes matter? And if so in what way. This build you recorded is a 9:1 balun. I’ve seen various other 9:1 Baluns that have the transformer SMD Size, to a 9:1 transformer IC all the way to a 9:1 balun in a box with a toroid the size of a fist. Yet they are all marketed for the same type of applications. I’d appreciate any feedback or wisdom you can share. As I watch your video and lookup these other examples , it dawns on me that I should be able to make my own from scratch. If I follow step by step and don’t take short cuts. Also, yes , the transceiver you featured is awesome but I went to the site and the way they are priced, you’d think they’re made of gold. And the there’s stock to ship completed units, there are no kit’s forthcoming for this model. I think there will be kits available for the 35 CW only Transceiver
The UNUN shown in this video is actually a 49:1, not a 9:1. A 49:1 is typically used to feed an End-Fed Half-Wave antenna since the feedpoint impedance is a few thousand ohms typically. A 9:1 unit is typically use with an end-fed random wire (not resonant, not a halfwave), and typically needs a counterpoise. The physical size of the toroid relates to the amount of power it can handle. The "type" or "mix" of the toroid determines largely what frequency range it is useful for.
@@w2aew Thanks for the response. You know, the part I was missing was the Tx portion of radio. Not being a licensed operator, I always consider everything in Rx only. Duh!! My bad. So to clarify, if I want to run a hidden random wire on my fence for Rx only , I can : 1. Run single random wire with 9:1 balun or 2. Run a counterpoise parallel to the random wire 3. Or can I run essentially a long wire dipole with equal lengths of wire extending away from each other. Please don’t spend a lot of your time answering these. I’ll get into the books tonight and figure it out. I’ve been spending all my time on microwave and Sat Com, I’ve missed a lot of the fundamentals I should’ve learned to begin with. Thanks again for time and all the knowledge you share through your media.
Apologies if this is a bit off of the topic which is the KM4CT kit. I would like to just order the kit but the shipping fee is a bit high. I have a T50-2, T50-6, and FT114-61 cores. Can I use any of this using the same winding as you do, 3 primary and 24 secondary?
Hello sir, Thanks for the videos. One day I tried to make a radio transmitter and receiver that would transmit and receive only 1bit signal, based on the things I studied on my books.But What I made was a failure and I felt very sad ,I didn't have any idea why i was not able to receive any signal at all. I searched whole youtube and everyone was making fm transmitter and others but i was only interested in making a simple 1bit tx rx. Please sir if possible make a video on that and explain about it. I love your teaching style and I think only you can teach me how to make it and how it works,Thank you so much!
@@w2aew This is what i did- i made an oscillator and connected an antenna. At the receiver side an antenna,tank circuit and output is connected to an amplifier. Output of the amplifier is connected to the oscope. What i saw was the signal was very poor. I mean not even detectable if it is even 1m apart from the transmitter. What was wrong? (I used same resonant circuit at the both transmitter and receiver)
@@kirom4265 What was your operating frequency? What type antenna did you use? Did you modulate it at all, or just transmitting a continuous signal? Did your amplifier at the other end have sufficient gain at the frequency you were operating at? Lots of things to get "right" in order for something like this to work.
@@w2aew yes could you make a video on just that? I and many others like me who is just starting out will get a great help from that video. If you do it it would be very helpful. Again , thank you so so much for responding. Thank you, from India
That's amazing. I'm wondering how they got your message?? Are they always listening for incoming signals?? That's too much work if they do so?? I don't know how it works
You are correct. The reverse beacon network uses a bunch of radio receivers connected to the Internet and when they decode you calling CQ it gets recorded. The digital equivalent (for RTTY, PSK31, FT8 etc) would be PSKreporter. It's extremely useful too because if you do Parks on the air or Summits on the air the system can use the reverse beacon network to spot you even if you don't have cell service.
@@w2aew Just kiddin'. :) That randomness actually fascinates me. The constraint of being respectful is pretty rare in our modern open-media-based culture. I imagine respectfulness is violated from time to time, what with, well... humans... and all, but overall I'm pretty impressed with the inertia of ham history, at least with what I've seen and heard.
Dear sir Thank you for the video.my call sign (VU2KND). please make a clear video for end fed half wave antenna vs end fed random wire. if i chose my wire length is (66 feet) can i use it for (40m) and all other bands (lower bands) also?. i am a big fan of you Thank you sir.
sir thank you for the response.what you said true. if we changing feed point from center(assume 50 ohms) to one end(assume 2500 ohms). how that changing the antenna behaving(multi band)?. @@w2aew
@@ornithopterindia The end-fed antenna impedance repeats every half wavelength. So this antenna is one half-wavelength on 40m, it is two half-wavelengths on 20m, three half-wavelengths on 15m and four half-wavelengths on 10m.
Excellent presentation! I've used those 2 mm banana plugs/jacks before and they make great lightweight and compact connectors. FB on the strain relief, good idea. Looks like a very nice little kit. [Aha, a misquote! "The proof of the pudding is in the eating." ;-) ]
transformers have a few different functions and applications. In this specific case we are transforming the impedance for use in an antenna. You see, a standard half wave dipole has a different impedance depending on where you feed it from. Typically you do this at the center point which is roughly 50 ohms just like our entire system. At the far ends of the antenna, it is 2400 ohms so we need to transform the 50 ohms to 2400 to form an impedance match. If you look, 50*49=2450 so we want to transform the impedance by a factor of 49, or have a turns ratio of 1:7 or 3:21. I'd recommend looking up "impedance matching transformer" and you will find plenty of good info on the subject. (there probably is a video on this channel too but I am not sure which one if there is)
As @JonathanKayne points out, this is really nothing more than a step-up transformer with a turns ratio of 1:7. Since the voltage is stepped up by 7 (and a transformer ideally doesn't consume power), that means that the voltage*current going in basically equals the voltage*current coming out. Since the voltage increases by a factor of 7, then the current must decrease by a factor of 7. Therefore, the impedance increases by the square of the turns ratio (7*7 = 49)
I got a very similar kit from K6ARK but sold it because I wanted something to wrap my wire. I'll have to deal with the throwing line as well, so some space will be required anyway. I have had some trouble wit the Elecraft T1 tuner I use with my KX3, which does not have the builtin tuner. Best estimate what bands bands I use efficiently with these EFHWs? Or is it a Radom wire? With the K6ARK the cap was used in one case. I'll be dusting off my IC-705 to use at the QTH, since it does have an ATU. I used it before I got the KX3 and thought it was pretty hot. I remember working a guy in my tiny hometown in Hunterdon Cty on PSK, and probably my G5RV. I just need to convert the RS-232 to USB on that PSK adapter. Have their been any software updates for the 705 in the last 20 years?! 72, Barry, VE7VIE and WV2J
The maker says that he took heavy inspiration from K6ARK, but made this one easier to build by not including any SMD components. A 40m EFHW (approx 66.5' long) will tune easily on 40, 20, 15 and 10m.
The kit can be made into either an end fed half wave which shouldn’t need a tuner (but will only be resonant on half wave multiples of the cut wire) or an end fed random wire which works on multiple bands with the aid of a tuner. Honestly if you have a T1 you technically don’t really need a random wire antenna. When I use my KX2 I typically just use 28.5 feet of wire and 28.5 foot counterpoise attached to a BNC to banana plug adapter. The T1 is such a great tuner that the matching unit becomes a bit redundant. Personally I like to deploy my EFHW with my radios that lack a tuner such as my 705, QCX, or FT-818nd. As for 705 updates I believe there was a firmware update earlier this year. I think the latest version is 1.32.
@@w2aew I can get 40-10 meters on my kx2. I actually use an antenna solution by Tufteln, but it’s more or less the same thing. Its just a male bnc connector, strain relief and 28.5 feet of polystealth. Slightly more compact than a standard binding post adapter but the same solution
@@JonathanKayne I'll definitely have to give that a try. I currently have a lot of antennas in my POTA kit. A Tufteln 40m EFHW, the MP1 vertical, another 40m EFHW (older/heavier), a 40/30 trapped EFHW and the 20m EFHW that I built in this video. I also have a pair of 28.5' wires, but I haven't tried using it yet. Should tune nicely with my KX2.
Thank you for doing a build of my new antenna kit!
For any ham radio clubs out there just wanted to let you know we offer a $5 discount per kit if you want to do a club kit build!
73 from Jonathan Kayne, KM4CFT
Thanks for the kits Jonathan!!
Just ordered one to go along with my QCX mini. It is neat to have an antenna from KM4CFT as he was my first ever CW contact
Nice little antenna! I like your banana plug idea. End fed antennas seem to be the latest craze and rightfully so. I always hear great signals come from them and it looks like you don't have to go too far off the ground to get a descent signal out. Quick and easy to set up as well. Thanks for showing and 73.
End Fed antennas had bad rap for a long time with stories of RF "in the shack", etc. which probably stemmed from the use of end fed random wires used without proper UNUNs and counterpoises. But a properly tuned EFHW really does work great - super easy to deploy, and works well when setup as a sloper, inverted V or vertical - just keep the feedpoint and end point a foot or more away from ground.
Nice kit! I like the fact that you can build it for either an EFHW or as an UNUN for an EFRW.
The only differences are how you wind the toroid and whether you include the counterpoise wire.
Thanks for the video Alan!!
I would love it if you could do these two sanity checks: (1) Please measure the insertion loss of two 49:1 un-uns wired back to back. That is, high impedance side connected to high impedance side. (2) Pease terminate the high impedance side of one un-un with a 2450 non-inductive resistor (2.2k is close enough) and measure the return loss (or VSWR) looking into the 50 ohm port. A nano-VNA would be the instrument to use.
Hello my friend this Jesus from Mexico, congrats for your videos
I love my TR-35 & TR-45L Skinny, that should be a great SOTA/POTA antenna for it! Cheers, Davey --KU9L
Hi Alan,
Nice build with great instructions, especially how to handle the soldering of the enameled wire. Had no doubts on the results. Stay safe. 73 WJ3U
I've built a couple of similar ones from qrpguys, i love how compact this one is though!
Interesting, thank you.
Great video, as always! Can you please share a link to the website that showed the stations that heard your signal?
The main starting page is: www.reversebeacon.net/index.php
SO DAMN FRUSTRATING! Great video. Learned a lot and plan to buy one of these. But I’m a new ham and have tried many times daily to get picked up the RBN on 40m and NOTHING. There must be a secret handshake or something. Absolutely maddening. But, I sure liked the build and look forward to getting it, building, and using it! Many thanks for posting.
The bands have not been in good shape the past few days. Also, the RBN isn’t great about picking up calls if the timing of your code isn’t perfect (which is why I used the keyer).
@@w2aew I’ve tried it with a straight key and a keyer. Nothing. Oh well. I use WebSDR and KiwiSDR to see where I reach.
Enjoyed the video. What was your source for your telescoping pole? Thanks
It is a Spiderbeam 40' telescoping pole. I bought it from DX Engineering.
I've built one but it reads dead flat on the antenna analyzer.
Solder is good, double checked wraps, wire has continuity.
Any ideas?
Is the capacitor of any special type to be working best in this application? Thank you Alan for all yours videos!
It's simply a 100pF 1kV capacitor. I find that as long as they are decent quality then they work fine. Any variation in capacitance would be sorted out when you prune the wire for the antenna
@@JonathanKayne @aktik6000 One interesting thing here is, most people specify a 1kV rated capacitor for this application. This really isn't necessary since the capacitor is on the low-voltage side of the transformer. Any decent RF-type of 100pf cap will do (ceramic NP0, silver-mica, etc.).
How to mesure impedance of 1:1 balun? And can I use same method to mesure 49:1 unun? (I want to compare balun wound up by coax vs wire pair)
👍
Great vid! Where do you source those banana jacks?
I used these: www.amazon.com/dp/B07NZMT7JL
@@w2aew Thank you!
Hello again. So, as I continue to learn as much as I can about the radio hobby and the field in general, I always come back to Baluns. I pretty much get the why and how, my new question is do the varying sizes matter? And if so in what way. This build you recorded is a 9:1 balun. I’ve seen various other 9:1 Baluns that have the transformer SMD Size, to a 9:1 transformer IC all the way to a 9:1 balun in a box with a toroid the size of a fist. Yet they are all marketed for the same type of applications. I’d appreciate any feedback or wisdom you can share. As I watch your video and lookup these other examples , it dawns on me that I should be able to make my own from scratch. If I follow step by step and don’t take short cuts.
Also, yes , the transceiver you featured is awesome but I went to the site and the way they are priced, you’d think they’re made of gold. And the there’s stock to ship completed units, there are no kit’s forthcoming for this model. I think there will be kits available for the 35 CW only Transceiver
The UNUN shown in this video is actually a 49:1, not a 9:1. A 49:1 is typically used to feed an End-Fed Half-Wave antenna since the feedpoint impedance is a few thousand ohms typically. A 9:1 unit is typically use with an end-fed random wire (not resonant, not a halfwave), and typically needs a counterpoise. The physical size of the toroid relates to the amount of power it can handle. The "type" or "mix" of the toroid determines largely what frequency range it is useful for.
@@w2aew Thanks for the response. I think I’m getting my head around it.
@@w2aew Thanks for the response. You know, the part I was missing was the Tx portion of radio. Not being a licensed operator, I always consider everything in Rx only. Duh!! My bad.
So to clarify, if I want to run a hidden random wire on my fence for Rx only , I can : 1. Run single random wire with 9:1 balun or 2. Run a counterpoise parallel to the random wire 3. Or can I run essentially a long wire dipole with equal lengths of wire extending away from each other.
Please don’t spend a lot of your time answering these. I’ll get into the books tonight and figure it out. I’ve been spending all my time on microwave and Sat Com, I’ve missed a lot of the fundamentals I should’ve learned to begin with. Thanks again for time and all the knowledge you share through your media.
@@TheElectronicDilettante Use 9:1 with random wire + counterpoise, or 49:1 with EFHW without counterpoise (coax acts as counterpoise), etc.
Apologies if this is a bit off of the topic which is the KM4CT kit. I would like to just order the kit but the shipping fee is a bit high. I have a T50-2, T50-6, and FT114-61 cores. Can I use any of this using the same winding as you do, 3 primary and 24 secondary?
You may have a slightly different frequency response with the different mixes, but definitely worth the experiment.
@@w2aew Thank you, I just have to learn the use of the nanoVNA.
@@itchysaddle I've got an entire playlist on that.
@@w2aew I've watched some of the video, didn't realize there is an entire playlist. I will watch all of it.
Hello sir,
Thanks for the videos.
One day I tried to make a radio transmitter and receiver that would transmit and receive only 1bit signal, based on the things I studied on my books.But What I made was a failure and I felt very sad ,I didn't have any idea why i was not able to receive any signal at all. I searched whole youtube and everyone was making fm transmitter and others but i was only interested in making a simple 1bit tx rx. Please sir if possible make a video on that and explain about it. I love your teaching style and I think only you can teach me how to make it and how it works,Thank you so much!
I don't understand your application. A 1 bit transmission can simply be done by turning a transmitter on (1) or off (0), like morse code.
@@w2aew This is what i did- i made an oscillator and connected an antenna.
At the receiver side an antenna,tank circuit and output is connected to an amplifier. Output of the amplifier is connected to the oscope. What i saw was the signal was very poor. I mean not even detectable if it is even 1m apart from the transmitter. What was wrong?
(I used same resonant circuit at the both transmitter and receiver)
@@kirom4265 What was your operating frequency? What type antenna did you use? Did you modulate it at all, or just transmitting a continuous signal? Did your amplifier at the other end have sufficient gain at the frequency you were operating at? Lots of things to get "right" in order for something like this to work.
@@w2aew yes could you make a video on just that? I and many others like me who is just starting out will get a great help from that video. If you do it it would be very helpful.
Again , thank you so so much for responding. Thank you, from India
That's amazing. I'm wondering how they got your message?? Are they always listening for incoming signals?? That's too much work if they do so?? I don't know how it works
You are correct. The reverse beacon network uses a bunch of radio receivers connected to the Internet and when they decode you calling CQ it gets recorded.
The digital equivalent (for RTTY, PSK31, FT8 etc) would be PSKreporter.
It's extremely useful too because if you do Parks on the air or Summits on the air the system can use the reverse beacon network to spot you even if you don't have cell service.
The proof of the pudding is in the eating.
How can you have your pudding? You can't have any pudding if you don't eat your meat.
73 de KF4LBG
And we all know what a 49:1 QRP End Fed UNUN for EFRW applications is?
This video is geared towards my ham radio subscribers, most of which are familiar with an end-fed halfwave antenna.
73
Whyncha just text? ;)
You make me wanna ham! I *really* need more hobbies!
Texting is no fun, and only for people you already know. *Radio* is random - you never know who you're going to meet and where they'll be located.
@@w2aew Just kiddin'. :)
That randomness actually fascinates me. The constraint of being respectful is pretty rare in our modern open-media-based culture. I imagine respectfulness is violated from time to time, what with, well... humans... and all, but overall I'm pretty impressed with the inertia of ham history, at least with what I've seen and heard.
@@ydonl Yes, I knew *you* were kidding, but I figured that other readers might not know that - hence my reply.
I prefer the known quantity of local 40/80 hams. It can be predictable.
CW is faster
Dear sir Thank you for the video.my call sign (VU2KND). please make a clear video for end fed half wave antenna vs end fed random wire.
if i chose my wire length is (66 feet) can i use it for (40m) and all other bands (lower bands) also?.
i am a big fan of you Thank you sir.
I found that if I tune my 40m EFHW (about 66.5' long") for the CW portion of the band, then it also presents a nice SWR on 20, 15 and 10m.
sir thank you for the response.what you said true. if we changing feed point from center(assume 50 ohms) to one end(assume 2500 ohms).
how that changing the antenna behaving(multi band)?.
@@w2aew
@@ornithopterindia The end-fed antenna impedance repeats every half wavelength. So this antenna is one half-wavelength on 40m, it is two half-wavelengths on 20m, three half-wavelengths on 15m and four half-wavelengths on 10m.
Thank you sir.@@w2aew
sir even harmonics like 20m,10m will transmit or cancel out each other(full wavelength) Thank you sir.
Excellent presentation! I've used those 2 mm banana plugs/jacks before and they make great lightweight and compact connectors. FB on the strain relief, good idea. Looks like a very nice little kit. [Aha, a misquote! "The proof of the pudding is in the eating." ;-) ]
Wow, how concise, I’m going to check your channel and might subscribe. KK7HI
I hope you like the rest of the videos on my channel just as much. I try to be concise, with little waffling.
FB! Nice kit and excellent demonstration
That looks a lot like a Metcal soldering station. Not many using those. I love mine.
Yes, I love my Metcal too! Fantastic temperature control and thermal feedback response, and short working distance.
Did you connect the antenna directly to the back of the radio or was there a section of coax that I missed?
I used about 25' of coax, which can be seen at 9:00 in the video.
I know a fair amount but have never really understood these transformers. Still don't. 🤔
transformers have a few different functions and applications. In this specific case we are transforming the impedance for use in an antenna. You see, a standard half wave dipole has a different impedance depending on where you feed it from. Typically you do this at the center point which is roughly 50 ohms just like our entire system. At the far ends of the antenna, it is 2400 ohms so we need to transform the 50 ohms to 2400 to form an impedance match. If you look, 50*49=2450 so we want to transform the impedance by a factor of 49, or have a turns ratio of 1:7 or 3:21.
I'd recommend looking up "impedance matching transformer" and you will find plenty of good info on the subject. (there probably is a video on this channel too but I am not sure which one if there is)
As @JonathanKayne points out, this is really nothing more than a step-up transformer with a turns ratio of 1:7. Since the voltage is stepped up by 7 (and a transformer ideally doesn't consume power), that means that the voltage*current going in basically equals the voltage*current coming out. Since the voltage increases by a factor of 7, then the current must decrease by a factor of 7. Therefore, the impedance increases by the square of the turns ratio (7*7 = 49)
I got a very similar kit from K6ARK but sold it because I wanted something to wrap my wire. I'll have to deal with the throwing line as well, so some space will be required anyway.
I have had some trouble wit the Elecraft T1 tuner I use with my KX3, which does not have the builtin tuner. Best estimate what bands bands I use efficiently with these EFHWs? Or is it a Radom wire? With the K6ARK the cap was used in one case.
I'll be dusting off my IC-705 to use at the QTH, since it does have an ATU. I used it before I got the KX3 and thought it was pretty hot. I remember working a guy in my tiny hometown in Hunterdon Cty on PSK, and probably my G5RV. I just need to convert the RS-232 to USB on that PSK adapter. Have their been any software updates for the 705 in the last 20 years?!
72, Barry, VE7VIE and WV2J
The maker says that he took heavy inspiration from K6ARK, but made this one easier to build by not including any SMD components. A 40m EFHW (approx 66.5' long) will tune easily on 40, 20, 15 and 10m.
The kit can be made into either an end fed half wave which shouldn’t need a tuner (but will only be resonant on half wave multiples of the cut wire) or an end fed random wire which works on multiple bands with the aid of a tuner.
Honestly if you have a T1 you technically don’t really need a random wire antenna. When I use my KX2 I typically just use 28.5 feet of wire and 28.5 foot counterpoise attached to a BNC to banana plug adapter. The T1 is such a great tuner that the matching unit becomes a bit redundant.
Personally I like to deploy my EFHW with my radios that lack a tuner such as my 705, QCX, or FT-818nd.
As for 705 updates I believe there was a firmware update earlier this year. I think the latest version is 1.32.
@@JonathanKayne I'm going to have to try the 28.5' x2 with the BNC-Banana adapter on my KX2. Do you even tune 40 with this?
@@w2aew I can get 40-10 meters on my kx2. I actually use an antenna solution by Tufteln, but it’s more or less the same thing. Its just a male bnc connector, strain relief and 28.5 feet of polystealth. Slightly more compact than a standard binding post adapter but the same solution
@@JonathanKayne I'll definitely have to give that a try. I currently have a lot of antennas in my POTA kit. A Tufteln 40m EFHW, the MP1 vertical, another 40m EFHW (older/heavier), a 40/30 trapped EFHW and the 20m EFHW that I built in this video. I also have a pair of 28.5' wires, but I haven't tried using it yet. Should tune nicely with my KX2.
73' 88'