Top vid Peter, I’ve been a ham for over 40 years and never stop learning. I always get something out of your videos the detail and pace is just right. What I’ve found with my Foundation classes is they need that push and extra know how, some of us take for granted, to get them on the air. 👍🏻👍🏻👍🏻
Sorry to be off topic but does anyone know of a trick to get back into an instagram account?? I was stupid lost the login password. I love any tips you can offer me.
@Gordon Eli I really appreciate your reply. I got to the site thru google and I'm waiting for the hacking stuff now. I see it takes a while so I will get back to you later when my account password hopefully is recovered.
Cheers for this. Build this antenna in about 20 mins. Never built a transformer before. Amazing. Worked Portugal 5 9 plus from London, and the the Orkneys, even stronger.
Many thanks, Peter. Having recently discovered your channel, I was glad to have seen this video, because my first attempt at winding the UNUN with the bifilar primary produced some results I couldn't understand, but definitely did not look good. I tried a couple more times, each one with a little better results, but still not quite what I would have expected. When I rebuilt it again using your single winding technique, I finally got some more believable results. An observation I wanted to make, however, is that given the tap point is 2 turns from the earth end of the transformer, using only 5 turns before and after the cross over results in a turns ratio of 10:2 (or 11:2 if the cross over is counted as one turn), which you identify as being less than the "recommended" number of turns. This would result in a 25:1 (or 30.25:1) impedance ratio. The usual references I've seen to EFHW UNUNs refer to a 49:1 ratio. I'd guess that the difference in the impedance matching characteristics of your design might be a partial explanation for the improved performance on the higher bands that you suggest. My thinking is that the impedance at the feed end of the EFHW wire is a bit different on each band (lower on the upper bands, so the match is better with a lower impedance ratio). At any rate, I'm looking forward to getting this antenna built and getting on the air again after a 40 year lapse. Thanks again, Peter. 73 Phil KE7HC, Michigan, USA.
Peter- this is "brilliant" as you Brits would say... I now have everything I need to build my HWEF 80/4020/10 antenna. By using the loading coil you covered in another video, I can fit it in my back yard between a tree and the house, AND I can get better resonance points on 40 to 10. I'll follow your advice and use an isolation transformer close to my rig. You've given me everything I need,,, including instructions on how to build it all myself if I want. Again- BRILLIANT! -Jake
Thank You for this. I'm still learning but my biggest issue is sourcing what I need to complete these projects..once I crack that nut, I can start building some things
You can purchase what you need on a well known online auction site. For the toroid core, try searching "Fair-Rite FT240-43". The 240 means it has a diameter of 2.4 inches. 43 is just the type of ferrite material. Suggest going for genuine Fair-Rite - as other brands of type 43 may look the same but not behave the same. For a capacitor, try "100pF 2KV ceramic capacitor". Also you will need something like a "SO-239 panel mount socket" (for connecting co-ax feed) and a couple of nuts and bolts for the antenna connection and ground or counterpoise. Of course you will need a box. If you want to have the transformer outside, suggest searching for "IP67 Electrical Enclosure". Give it a go. It's not difficult to collect the parts and make these. If you wrap connections to the transformer box in self-amalgamating tape, you can mount it outside and it will provide years of service.
Good Video, I think the EFHW deserves more promotion - minor point I think your transformer has 11 turns as the crossover turn ( the Riesert modification) counts as a turn -- 10,11,12 doesn't matter too much. (I use 14). The real issue - the one that may need experimenting with is the earthing and counterpoise arrangements. If your transformer is near the ground it is not a problem - just earth to a earth rod. But if the Trafo is up in the air then some people add a short wire counterpoise (0.05 of your lowest wavelength) or a choke a short distance down the coax (0.05 wavelength down the wire) - or just leave coax lying on the ground and hope any outer shield currents leak to earth before it gets to the shack. The chokes work best if good quality - 4k Ohms so you need another FT240. Also (always) worth adding additional chokes to all coax that enters your shack and adding an Earth Rod just outside the shack too. Of course if you don't bother it all still works... It would be nice if one arrangement worked and the others didn't - but all antennas "work" And RF in the shack is a mixed bag, sometimes you don't notice and it doesn't matter too much. For portable operation it doesn't matter at all I suppose. Thanks for putting out the video, I am looking forward to your next one and what you do for earthing. Best 73, MI5AFL
Hi Ian, You raise some interesting questions. There is much on the web about whether to earth or not to earth. I have tried short and long lengths of coax feeder. I have tried an earth and a counterpoise, and frankly have not come to any conclusions - all options seem to work well! My bottom line is always, does it work! Keep in touch. 73s Peter.
I am confused on the turn count looking at the toroid in the video. Looking at the top right , there are clearly 5 turns, it's the lower left that confuses me. In the video, Peter says two turns for the ground wire and then 5 more. So is there one turn hidden under the black wire tie? and then 5 more to the left? Does the wire that starts the winding - continue all around and come out the top? And then a second piece of wire is connected at the location where the left side if 100pF capacitor is soldered on ?
Being from the USA it took me a while to figure out why you wanted to put up your antenna in your garden. In the USA a garden is where you grow vegetables. Apparently what Brits call a garden is what Americans call a 'back yard', the property behind your house.
There's lots of designs for these around the I'net but many suffer from high loss. It would be interesting to measure 2 of these connected back-to-back on a network analyzer. Even a #47 pilot lamp at the 1-watt level can do this by comparing brilliance with and without the transformers. Use one on a power supply for a reference brightness to compare both cases with, then calculate the power in the lamp and the loss. Thanks for the vid. --N2GX
thank you for your video! quick question. you mention approx. 3000 ohms on a 40m 1/2-wave wire (468/7.5MHz = 62.4 feet of wire for 1/2-wave 40m). in order to reduce resistance on the wire to match a 50 ohm input, the unun / transformer needs a value of 60:1. so, do the 5 turns on each side of the ferrite shown along with the cap result in 50 ohms being shown to the coax?
3000 is an approximation and varies with height and location. 49:1 is by far the best option. The next option id 64:1 and the difference is minute! Go with 49:1.
Great vid. Will be making one but is that toroid really 65mm Diameter? It looks much smaller on the video against the capacitor and your pen. I have one 38mm OD / 24mm ID, will that work the same or will I require more / less turns please. Thanks
Hi Peter.. Great video as always.. I’ve been using this unun for a couple of months now with relatively excellent results given that I have a very poor antenna and antenna location.. There is no high level science involved in my conclusion..it got me back on the air (after a half century break!) and it works!! So thank you.. Could you take a guess as to the maximum power one should use with this unun.. It is slightly warm after a period of 100w CW.. Many thanks again for this, and all of your videos.. 73…John..G4EIJ.. Bristol
Peter- just to followup. I have all the materials and am ready to build following your video but I am confused on the turn count looking at the Toroid in the video. Looking at the top right , there are clearly 5 turns, it's the lower left that confuses me. In the video, you say two turns for the ground wire and then 5 more. So is there one turn hidden under the black wire tie? and then 5 more to the left? Does the wire that starts the winding - continue all around and come out the top? And then a second piece of wire is connected at the location where the left side if 100pF capacitor is soldered on ? so 12 turns altogether? Appreciate any clarification you can give. Tnx
Hi there. If you copy the illustration you will be OK. There are 2 turns, then a tap. Then 3 more turns before the wire crosses. Then there are five and a half turns which I think is pretty clear. BUT don't get too hung up on this. I did add an extra turn on the other side and all that happened was a slight improvement in matching on 80m and less good on 10m. The fact is that 80m - 10m is right on the limit and one turn more or one turn less simply skews it HF or LF. 73 Peter. 73 Peter.
Hi Peter from North Carolina. My name is Hank and really enjoy all of your vidieos. You and I might be the same age and I found that trying to make a transformer with awg 14 wire was more than these old fingers could do. I remembered seeing this video and have a question. What changes if any must I make to use a two 240-43 stack instead of a single torroid? I am looking for a 49:1 so my guess was a total of 14 windings. One of these days maybe we will be let out of confinement. You have been a great help to me and I know to others. Always wonder what's next. Regards and best 73's Hank K4CHD.
Hi Peter, I am learning lots from your videos. I recently purchased an Icom IC-7300 and, having a small garden, I am planning to build an EFHW antenna per your suggestions. Two questions: Is 65 mm the inside or outside diameter of your toroid core? And what is the gauge of the tinned copper wire you are using for the toroid winding? Thanks so much. Gordon VA3GSR
@@watersstanton Hi Peter, Thank you so much for answering my questions. It is appreciated. I have another question more general in this case. It concerns the length of the wire element. To connect the wire to the insulators you must fold it back and wrap it around the antenna wire somehow and fasten it there. That uses up some of the wire length and that means that the measured distance between the insulators on your support poles will be less than the required distance calculated by dividing 468 by frequency (MHz). My question is should the distance from insulator to insulator be the calculated length or is it only necessary that the wire element itself be the calculated length no matter how much is folded back in securing it to the insulators? Thank you. Gordon
Why do all the other 49:1 UnUn vids say to double up the primary wires and use 14 turns? Some want you to stack 2 toroids together. Really confused here.
Any advice for a total newbie just starting out and my first rig (gift from my son) a TYT TH-9000D and mic? I picked up the programming cable, have the software at the ready and using a magnetic auto whip antenna. I worked in cable television as a technician for many years and have prepped to build a rooftop dipole, RG-11 cable and high to 50 ohm matching transformer. Other than that basic install I'm struggling to get started. I'd picked up on station locally for a short bit. Thanks in advance if anyone has some guidance. Bless all!
I believe the radio you have is a VHF set - possibly covering the 2m ham radio band. Your best option is to purchase a fibre glass 2m vertical and install it outside or in the loft. Check out the Diamond X-30 model. Make sure you purchase the model with SO-239 socket. Then you need coax cable with PL-259 plug at either end to connect up to your set.
My EFHW acts like it is shorted. No noise on receive and high SWR. When I unscrew the shield from the pl259 and only the center is hooked to the so239 I get receive noise. What would cause this? Thanks for this great video!
Can you tell me why you would ever need more than a 100. Volt capacitor at 100. pF across the end of the Fifty Ohm coaxial cable, for a one hundred Watts signal? Ron W4BIN
(1) 50 ohms, if the load is matched; the SWR will be higher, perhaps 3:1, so the impedance at the coax may be 150 ohms. (2) Peak-to-peak RF voltage is usually a reasonable guide to select a DC working voltage rating for a capacitor. The peak-to-peak voltage will always be higher than the RMS voltage, particularly for complex waveforms, such as speech. Doing the arithmetic, 100 W RMS, 150 ohms yields 346 V peak-to-peak. A 500 VDC working voltage would be the smallest I would use for 100 W.
Hi Peter, I am learning lots from your videos, what would be the power rating of this matching transformer? And what size is the wire being used, and would larger wire give higher power rating?
It will handle 100W. The gauge is not too important. I think is was 20swg. Poer handling is largely determined by the number of cores. Two will probably handle 400W. 73 Peter
Hi Peter, in the video, you mentioned adding an extra turn to use on 80m, would it still work good on 40 and 20? Also, what would the ratio be with the 6 turns, I'm trying to understand the workings of it. Thanks for all the great videos...
Great video Pete, thank you.. Very inspiring channel.. I'm new to building my own antennas and components for the hobby. Does the gauge of wire have an effect? I was thinking 18 or 14 AWG rubber insulated..because I have this already...
Thanks Peter. I'm certainly no expert but in my experiences, I find that the worry you mention concerning bifilar "twisted" pairs shorting out may be a bit unwarranted. I hope the following explanation alleviates some of that concern when improved performance is desired. Shorts are almost non-existent in these applications and quite frankly, even when they do occur, they do not have drastic affects in this application that some folks might associate with "short circuits". Here's one way of thinking about it: Imagine winding your primary with a bifilar (twisted) pair where there are 1000 unexpected shorts occurring between the two bifilar wires of the common, shared lengths comprising the primary winding (not shorts between the two-turns themselves). If you think about it, the result of these shorts of the twisted pair would simply be to electrically convert these two conductors of the bifilar winding to a single conductor (which is exactly what you are doing here anyway!) . Taking this example to the extreme, let's say we use tinned, bare, un-insulated copper wire and, despite knowing better, we twist them together in a bifilar fashion (which, of course, shorts them together for their entire length to be used for the primary winding), and then using this resulting wire/s we wind the primary. Then, ignoring the fact that we KNOW that in actuality the bifilar pair is shorted together, we go ahead and connect their individual ends to form the primary as if we'd actually used insulated, annealed copper. What would be the end result? Electrically, the final result would simply be the exact same transformer circuit that you have wired and demonstrated here. That is, functionally, the shorted bifilar-wound bare wires would result in a single-conductor as the primary and the total transformer winding would be electrically center-tapped as in your original design. For emphasis: The twists would be completely shorted together forming one larger conductor for the first two turns, tapped at the same two-turn point as desired. Now, I'm not recommending doing this to any advantage, but rather only to illustrate the point. So, though a just a slight bit more challenging, I think your viewers might wish to consider using annealed copper (#14 magnet wire) and winding the primary's turns in a bifilar fashion which will reduce losses (core temps), improve efficiency, and improve performance in the lower frequency ranges among others. But, having said all this, for specific applications needing a quick & easy solution, this design that you have shared here focuses directly on 'simplicity' and as such, takes that prize. Thank you Peter. Well-presented. 73.
I’ve used enamelled copper wire with twisted for primary and if I put a meter across the so239 I have a short. Don’t know if this is expected or I’ve done something wrong.
Hi there, You are right if you add in the reverse point. I tried to make it simple and in fact one turn either way makes virtually no difference because it is a broad-band transformer. 73s Peter
watersstanton Did you bother to check the performance with a 2.7k non reactive restistor on the antenna side? Would be interesting to see if the traditional calculation holds for your design, which is more towards 1:30 than the traditional suggested 1:49 with a twisted primary.....
Thank you for your slow speaking style. It’s music to my old ears (and brain). Dave K8WPE since 1960
Many thanks for passing on your experience Peter. Very clear and great explanations. All your solutions are affordable and simple to impliment.
Top vid Peter, I’ve been a ham for over 40 years and never stop learning. I always get something out of your videos the detail and pace is just right. What I’ve found with my Foundation classes is they need that push and extra know how, some of us take for granted, to get them on the air. 👍🏻👍🏻👍🏻
Many thanks Mike. 73s Peter
Sorry to be off topic but does anyone know of a trick to get back into an instagram account??
I was stupid lost the login password. I love any tips you can offer me.
@Brantley Joaquin instablaster :)
@Gordon Eli I really appreciate your reply. I got to the site thru google and I'm waiting for the hacking stuff now.
I see it takes a while so I will get back to you later when my account password hopefully is recovered.
@Gordon Eli It worked and I now got access to my account again. I am so happy:D
Thanks so much you saved my ass :D
Cheers for this. Build this antenna in about 20 mins. Never built a transformer before. Amazing. Worked Portugal 5 9 plus from London, and the the Orkneys, even stronger.
Sid, glad you got good results - 73s Peter
Many thanks, Peter. Having recently discovered your channel, I was glad to have seen this video, because my first attempt at winding the UNUN with the bifilar primary produced some results I couldn't understand, but definitely did not look good. I tried a couple more times, each one with a little better results, but still not quite what I would have expected. When I rebuilt it again using your single winding technique, I finally got some more believable results.
An observation I wanted to make, however, is that given the tap point is 2 turns from the earth end of the transformer, using only 5 turns before and after the cross over results in a turns ratio of 10:2 (or 11:2 if the cross over is counted as one turn), which you identify as being less than the "recommended" number of turns. This would result in a 25:1 (or 30.25:1) impedance ratio. The usual references I've seen to EFHW UNUNs refer to a 49:1 ratio. I'd guess that the difference in the impedance matching characteristics of your design might be a partial explanation for the improved performance on the higher bands that you suggest. My thinking is that the impedance at the feed end of the EFHW wire is a bit different on each band (lower on the upper bands, so the match is better with a lower impedance ratio).
At any rate, I'm looking forward to getting this antenna built and getting on the air again after a 40 year lapse. Thanks again, Peter. 73 Phil KE7HC, Michigan, USA.
Peter- this is "brilliant" as you Brits would say...
I now have everything I need to build my HWEF 80/4020/10 antenna. By using the loading coil you covered in another video, I can fit it in my back yard between a tree and the house, AND I can get better resonance points on 40 to 10. I'll follow your advice and use an isolation transformer close to my rig.
You've given me everything I need,,, including instructions on how to build it all myself if I want.
Again- BRILLIANT!
-Jake
Really appreciate all the antenna videos.
Many thanks. 73s Peter.
Enjoy all of your videos Peter. This was one of your very best. Thanks! 73, George K2WO
Å
Thank You for this. I'm still learning but my biggest issue is sourcing what I need to complete these projects..once I crack that nut, I can start building some things
Many thanks Walter
You can purchase what you need on a well known online auction site. For the toroid core, try searching "Fair-Rite FT240-43". The 240 means it has a diameter of 2.4 inches. 43 is just the type of ferrite material. Suggest going for genuine Fair-Rite - as other brands of type 43 may look the same but not behave the same. For a capacitor, try "100pF 2KV ceramic capacitor".
Also you will need something like a "SO-239 panel mount socket" (for connecting co-ax feed) and a couple of nuts and bolts for the antenna connection and ground or counterpoise. Of course you will need a box. If you want to have the transformer outside, suggest searching for "IP67 Electrical Enclosure".
Give it a go. It's not difficult to collect the parts and make these. If you wrap connections to the transformer box in self-amalgamating tape, you can mount it outside and it will provide years of service.
Very informative and well presented, thanks Peter,
Thanks Matt. 73s Peter.
as always i love your input. you make learning easy to watch n see how..ty Sir..
Much appreciated/
Good Video, I think the EFHW deserves more promotion - minor point I think your transformer has 11 turns as the crossover turn ( the Riesert modification) counts as a turn -- 10,11,12 doesn't matter too much. (I use 14). The real issue - the one that may need experimenting with is the earthing and counterpoise arrangements. If your transformer is near the ground it is not a problem - just earth to a earth rod. But if the Trafo is up in the air then some people add a short wire counterpoise (0.05 of your lowest wavelength) or a choke a short distance down the coax (0.05 wavelength down the wire) - or just leave coax lying on the ground and hope any outer shield currents leak to earth before it gets to the shack. The chokes work best if good quality - 4k Ohms so you need another FT240. Also (always) worth adding additional chokes to all coax that enters your shack and adding an Earth Rod just outside the shack too. Of course if you don't bother it all still works...
It would be nice if one arrangement worked and the others didn't - but all antennas "work" And RF in the shack is a mixed bag, sometimes you don't notice and it doesn't matter too much. For portable operation it doesn't matter at all I suppose.
Thanks for putting out the video, I am looking forward to your next one and what you do for earthing. Best 73, MI5AFL
Hi Ian,
You raise some interesting questions. There is much on the web about whether to earth or not to earth. I have tried short and long lengths of coax feeder. I have tried an earth and a counterpoise, and frankly have not come to any conclusions - all options seem to work well! My bottom line is always, does it work! Keep in touch. 73s Peter.
I am confused on the turn count looking at the toroid in the video. Looking at the top right , there are clearly 5 turns, it's the lower left that confuses me. In the video, Peter says two turns for the ground wire and then 5 more. So is there one turn hidden under the black wire tie? and then 5 more to the left? Does the wire that starts the winding - continue all around and come out the top? And then a second piece of wire is connected at the location where the left side if 100pF capacitor is soldered on ?
Being from the USA it took me a while to figure out why you wanted to put up your antenna in your garden. In the USA a garden is where you grow vegetables. Apparently what Brits call a garden is what Americans call a 'back yard', the property behind your house.
Yes confusing! 73 Peter
That confused me as well, until I had a half-dozen of his videos under my belt. Then the light bulb went off. Haha
Lol, Out back is the whole of AUSTRALIA.😄
There's lots of designs for these around the I'net but many suffer from high loss. It would be interesting to measure 2 of these connected back-to-back on a network analyzer. Even a #47 pilot lamp at the 1-watt level can do this by comparing brilliance with and without the transformers. Use one on a power supply for a reference brightness to compare both cases with, then calculate the power in the lamp and the loss. Thanks for the vid. --N2GX
There is a much easier and more accurate way than using bulbs. ATU and RF current meter vs Transforner and RF current meter. 73 Peter.
thank you for your video! quick question. you mention approx. 3000 ohms on a 40m 1/2-wave wire (468/7.5MHz = 62.4 feet of wire for 1/2-wave 40m). in order to reduce resistance on the wire to match a 50 ohm input, the unun / transformer needs a value of 60:1. so, do the 5 turns on each side of the ferrite shown along with the cap result in 50 ohms being shown to the coax?
3000 is an approximation and varies with height and location. 49:1 is by far the best option. The next option id 64:1 and the difference is minute! Go with 49:1.
Thank you@@watersstanton !
Very good, I'm a tcw man myself,. So much easier to work with.
Thanks John. &3s Peter
Great vid. Will be making one but is that toroid really 65mm Diameter? It looks much smaller on the video against the capacitor and your pen. I have one 38mm OD / 24mm ID, will that work the same or will I require more / less turns please.
Thanks
Thanks very much for this! -
one question only - what is teh thickness of the wire? - does that matter at all?
Thanks Peter.So easy to do with that transformer.73
Ian G7HFS/PA3IKH
Thanks Ian. 73s Peter
I will be building this EFHW matcher soon.
Hi Peter.. Great video as always.. I’ve been using this unun for a couple of months now with relatively excellent results given that I have a very poor antenna and antenna location.. There is no high level science involved in my conclusion..it got me back on the air (after a half century break!) and it works!! So thank you..
Could you take a guess as to the maximum power one should use with this unun.. It is slightly warm after a period of 100w CW..
Many thanks again for this, and all of your videos..
73…John..G4EIJ.. Bristol
Hi there. I have never used more than 100W which is all the power I have. I suspect you can run a bit more on SSB bur NOT on FT8! 73 Peter.
@@watersstanton Thanks Peter..That’s all I have too.. It’s working great for me..so many thanks..John
BIG THANKS TO YOU PETE
Thanks Sheri. 73 Peter
Why is there an inverted L and inverted V but no upright L or V?
The L max radiation would be low to ground as would the V. No other reason.
Such great vids!
Peter- just to followup. I have all the materials and am ready to build following your video but I am confused on the turn count looking at the Toroid in the video. Looking at the top right , there are clearly 5 turns, it's the lower left that confuses me. In the video, you say two turns for the ground wire and then 5 more. So is there one turn hidden under the black wire tie? and then 5 more to the left? Does the wire that starts the winding - continue all around and come out the top? And then a second piece of wire is connected at the location where the left side if 100pF capacitor is soldered on ? so 12 turns altogether? Appreciate any clarification you can give. Tnx
Hi there. If you copy the illustration you will be OK. There are 2 turns, then a tap. Then 3 more turns before the wire crosses. Then there are five and a half turns which I think is pretty clear. BUT don't get too hung up on this. I did add an extra turn on the other side and all that happened was a slight improvement in matching on 80m and less good on 10m. The fact is that 80m - 10m is right on the limit and one turn more or one turn less simply skews it HF or LF. 73 Peter. 73 Peter.
Peter Tnx for reply and further explanation. I didn’t see the illustration you cite ?
Hi Peter from North Carolina. My name is Hank and really enjoy all of your vidieos. You and I might be the same age and I found that trying to make a transformer with awg 14 wire was more than these old fingers could do. I remembered seeing this video and have a question. What changes if any must I make to use a two 240-43 stack instead of a single torroid? I am looking for a 49:1 so my guess was a total of 14 windings. One of these days maybe we will be let out of confinement. You have been a great help to me and I know to others. Always wonder what's next. Regards and best 73's Hank K4CHD.
Hi Hank. Great to hear you are watching the videos.
Hi, what gauge tinned copper wire did you use thanks
Hi there, 18swg. 73s Peter
Hi Peter, I am learning lots from your videos. I recently purchased an Icom IC-7300 and, having a small garden, I am planning to build an EFHW antenna per your suggestions. Two questions: Is 65 mm the inside or outside diameter of your toroid core? And what is the gauge of the tinned copper wire you are using for the toroid winding? Thanks so much. Gordon VA3GSR
65mm is outside diameter, Wire is 18 swg but nit critical. You will love tge antenna. 73 Peter
@@watersstanton Hi Peter, Thank you so much for answering my questions. It is appreciated. I have another question more general in this case. It concerns the length of the wire element. To connect the wire to the insulators you must fold it back and wrap it around the antenna wire somehow and fasten it there. That uses up some of the wire length and that means that the measured distance between the insulators on your support poles will be less than the required distance calculated by dividing 468 by frequency (MHz). My question is should the distance from insulator to insulator be the calculated length or is it only necessary that the wire element itself be the calculated length no matter how much is folded back in securing it to the insulators? Thank you. Gordon
Why do all the other 49:1 UnUn vids say to double up the primary wires and use 14 turns? Some want you to stack 2 toroids together. Really confused here.
Stacking increases power rating. My winding is an option but it is simple and it works!
@@watersstanton oh that makes sense. Thank you the reply and the great videos. 73
Any advice for a total newbie just starting out and my first rig (gift from my son) a TYT TH-9000D and mic? I picked up the programming cable, have the software at the ready and using a magnetic auto whip antenna. I worked in cable television as a technician for many years and have prepped to build a rooftop dipole, RG-11 cable and high to 50 ohm matching transformer. Other than that basic install I'm struggling to get started. I'd picked up on station locally for a short bit. Thanks in advance if anyone has some guidance. Bless all!
I believe the radio you have is a VHF set - possibly covering the 2m ham radio band. Your best option is to purchase a fibre glass 2m vertical and install it outside or in the loft. Check out the Diamond X-30 model. Make sure you purchase the model with SO-239 socket. Then you need coax cable with PL-259 plug at either end to connect up to your set.
My EFHW acts like it is shorted. No noise on receive and high SWR. When I unscrew the shield from the pl259 and only the center is hooked to the so239 I get receive noise. What would cause this? Thanks for this great video!
Almost certainly there is a fault on the 49:1 transformer or the cox plug into the transformer. Peter.
@@watersstanton Bending the coax a certain way at the pl-259 cause it to short out. Thank you!
Can you tell me why you would ever need more than a 100. Volt capacitor at 100. pF across the end of the Fifty Ohm coaxial cable, for a one hundred Watts signal? Ron W4BIN
Capacitors are rated at DC. We are dealing with RF. The load will never be zero VSWR and can rise rise significantly. Try 100V and see them pop! Peter
(1) 50 ohms, if the load is matched; the SWR will be higher, perhaps 3:1, so the impedance at the coax may be 150 ohms.
(2) Peak-to-peak RF voltage is usually a reasonable guide to select a DC working voltage rating for a capacitor. The peak-to-peak voltage will always be higher than the RMS voltage, particularly for complex waveforms, such as speech.
Doing the arithmetic, 100 W RMS, 150 ohms yields 346 V peak-to-peak. A 500 VDC working voltage would be the smallest I would use for 100 W.
Thanks a lot for this video, 73, Olivier HB9HIW
You are welcome! 73 Peter
Regarding your comment on the "100 puff" capacitor. Is that a colloquial way of saying "100 picofarads"?
Yes it is. 73 Peter
Hi Peter, I am learning lots from your videos, what would be the power rating of this matching transformer?
And what size is the wire being used, and would larger wire give higher power rating?
It will handle 100W. The gauge is not too important. I think is was 20swg. Poer handling is largely determined by the number of cores. Two will probably handle 400W. 73 Peter
@@watersstanton When you say 2 cores, how would that be configured?
Hi Peter, in the video, you mentioned adding an extra turn to use on 80m, would it still work good on 40 and 20?
Also, what would the ratio be with the 6 turns, I'm trying to understand the workings of it.
Thanks for all the great videos...
I have an efhw and my Balun is about 3 feet from the ground.
Should it be higher since most of the power comes from that end?
No problem. The power is actually distributed among the whole length.
Great video Pete, thank you..
Very inspiring channel..
I'm new to building my own antennas and components for the hobby.
Does the gauge of wire have an effect?
I was thinking 18 or 14 AWG rubber insulated..because I have this already...
No - 16 or 18swg Peter
@@watersstanton Thanks for the reply..got it..👍
What gauge wite should I use and can wire have a plastic cover or does it need to be bare. Thanks for all you do. KH6JMK
18swg but not super critical.
Thanks Peter. I'm certainly no expert but in my experiences, I find that the worry you mention concerning bifilar "twisted" pairs shorting out may be a bit unwarranted. I hope the following explanation alleviates some of that concern when improved performance is desired.
Shorts are almost non-existent in these applications and quite frankly, even when they do occur, they do not have drastic affects in this application that some folks might associate with "short circuits". Here's one way of thinking about it: Imagine winding your primary with a bifilar (twisted) pair where there are 1000 unexpected shorts occurring between the two bifilar wires of the common, shared lengths comprising the primary winding (not shorts between the two-turns themselves). If you think about it, the result of these shorts of the twisted pair would simply be to electrically convert these two conductors of the bifilar winding to a single conductor (which is exactly what you are doing here anyway!) . Taking this example to the extreme, let's say we use tinned, bare, un-insulated copper wire and, despite knowing better, we twist them together in a bifilar fashion (which, of course, shorts them together for their entire length to be used for the primary winding), and then using this resulting wire/s we wind the primary. Then, ignoring the fact that we KNOW that in actuality the bifilar pair is shorted together, we go ahead and connect their individual ends to form the primary as if we'd actually used insulated, annealed copper. What would be the end result? Electrically, the final result would simply be the exact same transformer circuit that you have wired and demonstrated here. That is, functionally, the shorted bifilar-wound bare wires would result in a single-conductor as the primary and the total transformer winding would be electrically center-tapped as in your original design. For emphasis: The twists would be completely shorted together forming one larger conductor for the first two turns, tapped at the same two-turn point as desired. Now, I'm not recommending doing this to any advantage, but rather only to illustrate the point.
So, though a just a slight bit more challenging, I think your viewers might wish to consider using annealed copper (#14 magnet wire) and winding the primary's turns in a bifilar fashion which will reduce losses (core temps), improve efficiency, and improve performance in the lower frequency ranges among others. But, having said all this, for specific applications needing a quick & easy solution, this design that you have shared here focuses directly on 'simplicity' and as such, takes that prize. Thank you Peter. Well-presented. 73.
Hi there. I was referring to the often used twisted input pair which could result in a dead short. Peter
watersstanton I guess I didn’t explain it clearly enough. A “dead short”? No. I don’t know how to say it any other way. 73
I’ve used enamelled copper wire with twisted for primary and if I put a meter across the so239 I have a short. Don’t know if this is expected or I’ve done something wrong.
So this is a 25:1 matching transformer?
No.
@@watersstanton You've wound eleven turns!
Peter can you confirm size of the capacitor? was it 100 pf?? tnx Paul
i used 2x220pf in series. So 100pf is fine. Not super crytical.
@@watersstanton I would just as soon use what is best. So for mostly 20m and 40m what would be the IDEAL capacitor size to use to use?? thanks Paul
It looks like 11 turns to me.
Hi there,
You are right if you add in the reverse point. I tried to make it simple and in fact one turn either way makes virtually no difference because it is a broad-band transformer. 73s Peter
watersstanton
Did you bother to check the performance with a 2.7k non reactive restistor on the antenna side?
Would be interesting to see if the traditional calculation holds for your design, which is more towards 1:30 than the traditional suggested 1:49 with a twisted primary.....
Hi..why do we need capacitor here? TNX
It helps matching above 14MHz - Peter
Great Video. Thank you.
Thanks Martin.
Zl1gam