Dan, Some time ago I challenged G0KSC on a balun issue - you can read the discussion here: http://www.g0ksc.co.uk/forum/2-antenna-discussions-here/122-pawsey-stub-error.html You might want to read th
I make it about 60uH if everything is constructed from #14 bare copper wire. That would vary if the vertical section was tubing. 73, Steve G3TXQ _______________________________________________ ______
A loading coil at the base of the vertical section doesn't alter Rrad, but one positioned at the top of the vertical section *does*, by altering the current distribution. With the dimensions given, a
Tom, Wanted signals are EM waves; noise signals are also EM waves. I wonder what characteristic of a Double Bazooka might allow it to distinguish wanted EM waves from unwanted ones in a way that a co
Mark, I guess a couple of considerations would be the variation in radiation elevation pattern and the feedpoint impedance - can the tuner handle it? If we take as a benchmark a quarter-wave vertical
Here's the signal strength at 10 degrees elevation from a 43ft vertical, referenced to the value on 40m: 30m: +0.8dB 20m: +3.0dB 17m: -0.1dB 15m: -2.2dB 12m: -1.6dB 10m: -1.8dB OK, it falls off a bit
I think we sometimes concentrate too much on looking at antenna heights that will maximise gain at certain take-off angles, and forget about the nulls. Those deep elevation nulls can be "killers" if
Plus - the second antenna might not need to cover all the bands if he chooses the heights carefully. Steve G3TXQ _______________________________________________ ______________________________________
Tony, Yes, it's possible if the conducted common-mode path happens to be low impedance compared to the Yagi impedance, and if the balun fails in a way that allows large common-mode current to flow. B
Tony, I made some azimuth plot measurements on my hexbeam with various CM choke arrangements, including "none": http://www.karinya.net/g3txq/hexbeam/common_mode/ The most sensitive indicator of CM is
Tony, It would be the length from the feedpoint to the ground; you also need to factor in the Common-Mode velocity factor of the line - probably in the range 0.95 to 0.99. If I model that feedline le
John, All that I've ever measured lie in the range 0.95 to 0.99. Did you notice that I said *COMMON-MODE* velocity factor? Signals flowing on the outside of the braid are Common-Mode signals - signal
Jim, I frequently talk to folk who question the utility of CM chokes at the antenna feedpoint. I find that one or more of the following questions usually helps them "see the light": 1. Would you inte
Not a direct answer to your question, but from Dan's (N3OX) web site: http://n3ox.net/files/23_adapters_28400kHz.jpg 23 connectors/adaptors including UHF types, 0.08dB loss on 10m 73, Steve G3TXQ ___
K7FR ran an experiment in the measurements lab at Washington State University, passing 1kW through a PL259/SO239 pair and measuring the loss with a calorimeter. He measured 1.8W loss at 30MHz: that's
I just did a short experiment at 28MHz, concentrating on the mismatch issue: AIM4170 Analyser (N-type) connected directly to precision load (N-type): Z = 49.916 - j0.28 Rho = 0.00293 SWR = 1.006 Then
Just to illustrate that last point: Consider a perfect 50 Ohm load connected to a source through three 6ft lengths of 50 Ohm lossless coax with Vf=0.66. The three lengths of coax are joined with two
Whoops - forgot to say: all that was calculated for a frequency of 28MHz. 73, Steve G3TXQ _______________________________________________ _______________________________________________ TowerTalk mai
Fred, If you had 0.3dB loss in a connector I doubt you or the guy at the other end would hear the difference. But if you ran 1.5kW through it you'd probably smell the difference! 100w is a lot of pow