Jim and Dave Let's start with Kevin KD5ONS and his 40m vertical. A great monobander and I'm sure it performs very well on that band. He tells us it works great on most other HF bands as well, using the wonderful Elecraft matching ability. Had he stayed with that one antenna on that one band there would be nothing more to say, but he desires a multi-band antenna and he now thinks he's got one, thanks to Elecraft. However, as Jim points out, the matching unit doesn't make his antenna work any better, it hides the losses to make us feel better. Kevin is no doubt blissfully unaware of the loss in the feeder and in the matching unit because it just works for him and he's a happy customer. He is also unaware of the high voltages appearing in the matching unit. I'm not sure how much power he's running but those conditions could lead to failure and I want to advise him of the risk.
This is where the phrase "it can be undesirable to have" comes in and the follow-on advice to make it non-resonant on any band to avoid potentially damaging conditions. I'm not saying anything new, I'm sure I read about this when solid state RF amplifiers first came on the scene. I don't want to make assumptions about Kevin, but I guess he might not yet be aware and ready to evaluate the vswr on his feeder for the other bands and work out the transformation of voltages back at the rig. Perhaps we should take the time and ask him: Kevin, what length and type of coax are you using to feed your 40m vertical? What power are you running? If he answers, I'm sure you will be able to help him do math. The great thing about this net is there are so many good folks willing to help and I'm glad of the chance to raise this old subject. I suspect for most of us, we don't have the space for mono-banders and multi-band antennas are the only practical solution and I'm very grateful for the matching ability of my Elecraft rig, but I'm cautious, I wouldn't run a mono-band antenna on another band without checking with my antenna analyser first, but that's another amazing story. David G3UNA > On 01 August 2020 at 23:09 Jim Brown <j...@audiosystemsgroup.com> wrote: > > > On 8/1/2020 12:12 PM, David Gilbert wrote: > > My gripe with the original post from G3UNA was simply his generalization > > that resonant antennas are bad and that non-resonant antennas are good. > > Same here. Most antennas that we can install are some form of > compromise. Higher is better. One size fits all solutions generally > don't perform as well as antennas optimized for a band or given > application. Antenna tuners do NOT make an antenna work better, they > simply allow the transmitter to put power into the feedline, and by > optimizing the load that the transmitter sees, they reduce the > distortion that the amplifier produces. Remember -- SWR is NOT a measure > of antenna performance. Louder at the other guy's radio IS. Less RX > noise IS. > > What we all would do if we could is often very different from what we > CAN do. What we would rig to operate from a park bench or on a > mountaintop is usually very different from what we would do at home. > > 73, Jim K9YC > ______________________________________________________________ > 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 d.cut...@ntlworld.com ______________________________________________________________ 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
