Re: [Elecraft] Choke for QRP with unbalanced antennas?
Hi Julie, A unun is an auto-transformer, not a choke. It is a matching device. Does your antenna include a counterpoise? It should -- it's a critical half of of an end-fed antenna, carrying return current. Without it, return current flows on whatever wiring is connected to your rig, and what that's connected to, which SHOULD be Ground, at minimum via the Green wire at the power outlet. 73, Jim K9YC On 11/20/2021 10:09 AM, Julia Tuttle wrote: If this were a fixed antenna, I'd just slap one of the LDG RU-1:1 ununs on it as a choke, but they're pretty chunky -- they're rated for 100 W CW, and have SO-239 connectors, which would require adapters on both sides in this setup. Does anyone know of a choke more appropriate for this kind of setup? I'd prefer something smaller (rated for maybe ~40-50 W continuous?) and natively BNC, so I don't need to juggle adapters. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Choke for QRP with unbalanced antennas?
The problem occurs when the counterpoise doesn't provide a low impedance path for RF. If the problem occurs on a specific band, then try a counterpoise that is about 1/4 wavelength long on that band. You can add one in addition to the existing counterpoise, if that one is working properly on the other bands. You might have to play with it because the appropriate length of a wire lying on the ground will not be the same as one in the air. Regarding ratings, you are lucky if "100w CW" actually means 100 watts at 50% duty cycle! It certainly doesn't mean 100w continuous. 73, Victor, 4X6GP Rehovot, Israel CWops #5 Formerly K2VCO https://www.qsl.net/k2vco/ On 20/11/2021 20:09, Julia Tuttle wrote: Hi folks, I was tinkering with a whip + counterpoise antenna connected to my KX3 by a short stretch of coax with BNC connectors a couple nights ago, and discovered (painfully) that there was quite a bit of RF coming back along the ground when I bumped the outside of the antenna connector. I know from experience that the KXPD3 can end up tingly in turn, and I'd like to avoid that. If this were a fixed antenna, I'd just slap one of the LDG RU-1:1 ununs on it as a choke, but they're pretty chunky -- they're rated for 100 W CW, and have SO-239 connectors, which would require adapters on both sides in this setup. Does anyone know of a choke more appropriate for this kind of setup? I'd prefer something smaller (rated for maybe ~40-50 W continuous?) and natively BNC, so I don't need to juggle adapters. More broadly, is this the appropriate way to fix this problem? This was with the counterpoise extended as best I could, and with the radio powered from mains (which may have actually made the problem *worse* by providing a more attractive path than the counterpoise?). (As an aside, when components like baluns/ununs or tuners are rated as "100 W CW, 200 W SSB", do they mean literally a continuous wave, or do they mean CW at a standard Morse duty cycle of roughly 50%?) Thanks and 73, Julie __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Choke for QRP with unbalanced antennas?
Make a choke with RG-316 - small size and can handle quite a lot of power. Bert VE3NR On 2021-11-20 13:09, Julia Tuttle wrote: Hi folks, I was tinkering with a whip + counterpoise antenna connected to my KX3 by a short stretch of coax with BNC connectors a couple nights ago, and discovered (painfully) that there was quite a bit of RF coming back along the ground when I bumped the outside of the antenna connector. I know from experience that the KXPD3 can end up tingly in turn, and I'd like to avoid that. If this were a fixed antenna, I'd just slap one of the LDG RU-1:1 ununs on it as a choke, but they're pretty chunky -- they're rated for 100 W CW, and have SO-239 connectors, which would require adapters on both sides in this setup. Does anyone know of a choke more appropriate for this kind of setup? I'd prefer something smaller (rated for maybe ~40-50 W continuous?) and natively BNC, so I don't need to juggle adapters. More broadly, is this the appropriate way to fix this problem? This was with the counterpoise extended as best I could, and with the radio powered from mains (which may have actually made the problem *worse* by providing a more attractive path than the counterpoise?). (As an aside, when components like baluns/ununs or tuners are rated as "100 W CW, 200 W SSB", do they mean literally a continuous wave, or do they mean CW at a standard Morse duty cycle of roughly 50%?) Thanks and 73, Julie __ Elecraft mailing list Home:http://mailman.qth.net/mailman/listinfo/elecraft Help:http://mailman.qth.net/mmfaq.htm Post:mailto:Elecraft@mailman.qth.net This list hosted by:http://www.qsl.net Please help support this email list:http://www.qsl.net/donate.html Message delivered tove...@bell.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Choke for QRP with unbalanced antennas?
I use a large ferrite clamp-on to isolate my short whip/counterpoise from my KX2. Needed tor running digital modes. The large variety will hold 3 turns of RG-58 which seems to be enough for what I need. IIRC I got them from ProAudio Engineering. GL 73, Brian, K0DTJ > On Nov 20, 2021, at 10:10, Julia Tuttle wrote: > > Hi folks, > > I was tinkering with a whip + counterpoise antenna connected to my KX3 by a > short stretch of coax with BNC connectors a couple nights ago, and > discovered (painfully) that there was quite a bit of RF coming back along > the ground when I bumped the outside of the antenna connector. I know from > experience that the KXPD3 can end up tingly in turn, and I'd like to avoid > that. > > If this were a fixed antenna, I'd just slap one of the LDG RU-1:1 ununs on > it as a choke, but they're pretty chunky -- they're rated for 100 W CW, and > have SO-239 connectors, which would require adapters on both sides in this > setup. > > Does anyone know of a choke more appropriate for this kind of setup? I'd > prefer something smaller (rated for maybe ~40-50 W continuous?) and > natively BNC, so I don't need to juggle adapters. > > More broadly, is this the appropriate way to fix this problem? This was > with the counterpoise extended as best I could, and with the radio powered > from mains (which may have actually made the problem *worse* by providing a > more attractive path than the counterpoise?). > > (As an aside, when components like baluns/ununs or tuners are rated as "100 > W CW, 200 W SSB", do they mean literally a continuous wave, or do they mean > CW at a standard Morse duty cycle of roughly 50%?) > > Thanks and 73, > > Julie > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to huntin...@coastside.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Choke for QRP with unbalanced antennas?
Hi folks, I was tinkering with a whip + counterpoise antenna connected to my KX3 by a short stretch of coax with BNC connectors a couple nights ago, and discovered (painfully) that there was quite a bit of RF coming back along the ground when I bumped the outside of the antenna connector. I know from experience that the KXPD3 can end up tingly in turn, and I'd like to avoid that. If this were a fixed antenna, I'd just slap one of the LDG RU-1:1 ununs on it as a choke, but they're pretty chunky -- they're rated for 100 W CW, and have SO-239 connectors, which would require adapters on both sides in this setup. Does anyone know of a choke more appropriate for this kind of setup? I'd prefer something smaller (rated for maybe ~40-50 W continuous?) and natively BNC, so I don't need to juggle adapters. More broadly, is this the appropriate way to fix this problem? This was with the counterpoise extended as best I could, and with the radio powered from mains (which may have actually made the problem *worse* by providing a more attractive path than the counterpoise?). (As an aside, when components like baluns/ununs or tuners are rated as "100 W CW, 200 W SSB", do they mean literally a continuous wave, or do they mean CW at a standard Morse duty cycle of roughly 50%?) Thanks and 73, Julie __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
