[TowerTalk] tower resonances

[Rudy Severns]

Wow,  I didn't realize this was such a hot topic!

My interest is driven by a recent practical problem.   I was helping a 
friend with a new 80m 4-square.  He had done a wonderful job mechanically. 
The array was very symmetrical and looked great.  I then proceeded to do the 
standard measurements: i.e. element self impedances, coupling impedances, 
etc.  It soon became very clear that while the array as mechanically 
symmetrical it was very asymmetric electrically.  The readings were really 
crazy!  It was obvious that one or more of the not too distant towers was 
interacting strongly with the array.  The whole project came to a screeching 
halt until we could sort out which tower(s) was the culprit(s) and then 
properly detune it.  I should have checked each of the towers ahead of time, 
identified a possible bad actor and fixed the problem in advance so that the 
array tuning could have proceeded without interruption.  I should have known 
better but I've learned my lesson this time.

I'll be happy to share my technique but I think it would be best if I wrote 
up a short description along with a couple of photos of the arrangements and 
also a graph or two of actual results.  Give me a couple of days and I'll 
post this on my web site and give the reflector a heads-up when it's there.

Thanks for your comments and help.  Several knowledgeable people have been 
pointed out to me and I'll be contacting them. Towers with a bunch of 
stacked Yagis on ring rotors make some of the standard detuning techniques 
difficult.

Again, Thanks and 73, Rudy N6LF