On 12/13/2011 12:53 PM, David Herring wrote: > I'd like to ask a few questions.
David, I hardly know where to begin in responding to your question. First, if you want a self-supporting vertical antenna for 30-10M, there are some really good choices that you can buy, that can be easily installed, that can be fed with 50 ohm coax, that don't require radials, and that don't require a balanced tuner. Loss in the feedline should be quite small if you use RG8 (or even RG8X). Look at the Hy-Gain AV-640, which one of my friends has used to work a lot of DX and do contesting from a small city lot. You should use one of my chokes at the feedpoint of this antenna. See my RFI tutorial, previously referenced. IMO, balanced tuners and so-called balanced line are highly over-rated solutions to problems that don't exist, or that could be better solved with other far simpler and less costly means. IMO, the only GOOD use of high impedance parallel wire feedlines is for very long runs -- 500 ft or more. Likewise, I am not a fan of all-band non-resonant dipole antennas, primarily because it is mechanically difficult choke them at their feedpoint, which makes them noisy and puts RF on the feedline, but also because their directional patterns vary widely with frequency. Since you're trying to make a vertical work on all bands, I'm assuming that horizontal antennas are not practical for you, hence the recommendation for the AV-640. I'm not a fan of compact, multi-band verticals below 40M because their efficiency tends to be poor, but at 30M and above they can work quite well. As to RF in the shack -- nearly all RF in the shack problems are the result of Pin One Problems in equipment. See the RFI tutorial for an explanation and solutions. Also see the pdf on Ham Interfacing for detailed instructions about bonding all of your gear together with short lengths of copper wire. This kills hum and buzz, and makes a big dent in the RFI you're experiencing. In extreme cases you may need to add chokes to individual cables. http://audiosystemsgroup.com/publish.htm 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
