One of my favorite portable antennas is a homebrewed link dipole for 40, 30, and 20m. I tuned it very carefully for the middle of the CW portion of each band, but it's still fairly well tuned in the SSB portions of 40 and 20. I still use a tuner with it for phone, though, just to keep from stressing the radio. If I'm using my KX3, the internal tuner works just fine. If the radio doesn't have a builtin tuner, I have an Elecraft T1 that I use. If it's by some weird quirk of fate a radio that puts out too little for the T1 to register (a couple of my QRPp radios are like that), I pull out the ZM-2, and everything is cream cheese. (Cream cheese? Yes. https://youtu.be/c0m5wJRGHEQ)
I still have a project hanging fire to try a fan dipole using horse farm electric fence webbing. It's poly webbing about 2" wide with 15 stainless-steel wires run lengthwise through the weave. I know they'll interact, but maybe with very careful trimming I can get it all to tune. With 3 bands, or maybe just 2, I'll have multiple wires for each band, and if I tune THOSE to a spread frequency set, maybe I can get a very wide bandwidth AND multiple bands on a single dipole strap. Or perhaps a vertical with counterpoise radials? Not sure which I want to experiment with. But I've got a lot of that strap (it was fairly cheap) and there's a nice clamp-on connector that connects all of the wires at once to a single connection for the power connections in its normal usage, but will also serve as a good feedpoint. Worth a try. If nothing else, I can rule out a multi-band fan and just go with a single band and get REALLY good bandwidth. (A company already sells monoband dipoles made of similar strap, but they charge through the NOSE.) But a link dipole is my favorite multi-band antenna, at least for portable use, where connecting and disconnecting the links isn't a big deal. It'd be a nightmare for a fixed base antenna...you'd have to use some kind of high-voltage, high-current relay, then you'd have the control wires interfering with the tuning...ack. Maybe SteppIR can try it...but then, if I was going to get a SteppIR, I'd get the new vertical that extends or retracts a tape up and down a PVC column to tune for each band, sort of like the "measuring tape" version of a screwdriver antenna. I still intend to make an automatic clothesline antenna using a stepper motor and a microcontroller at some point. I'll probably crib some of the control circuits from Jack's new book when it comes out! -=-=-=-=-=-=-=-=- 73, Gwen, NG3P On Sun, Aug 2, 2020 at 9:24 AM CUTTER DAVID via Elecraft < elecraft@mailman.qth.net> wrote: > 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 ard...@gmail.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
