[TowerTalk] SWR shifts with power

[Tom Osborne]

All the sections bonded together real good?  73
Tom W7WHY


> I'm having trouble with my shunt-fed 15m tower. I have an L matching  
> network that is switched between 80 and 160m. A relay selects  
> different taps on the inductor, and also adds capacitance for 160m.
> 
> If I use an MFJ 259 antenna analyzer, I can get a nice match on  
> either band. And if I transmit with a few watts, I have no problem.  
> Even the 20 watts that the KAT100 uses isn't a problem.
> 
> However, if I transmit about 70 watts or more, the SWR suddenly  
> shifts to 3:1 or worse. It changes with each transmission.
> 
> I thought the caps might be arcing, so I replaced one of them with a  
> wide-spaced variable, same problem.
> 
> Any suggestions?
> 
> 
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
> Quote: "Not within a thousand years will man ever fly!"
>             -- Wilbur Wright, 1901
> 
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