[TowerTalk] TH7-DX 15M problem

[Pete Smith N4ZR]

Or a feedline connector that happens to be at a current or voltage node 
on 15?

73, Pete N4ZR
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On 8/26/2015 3:43 PM, David Robbins wrote:
> a problem with the amp?
>
>
> Aug 26, 2015 03:28:05 PM, kzerohb at gmail.com wrote:
>
> I have an odd issue with a TH7-DXS.
>
> A while back I started to see a higher-than normal SWR, just on 15M, and just when running some smoke.
>
> While barefoot the problem never arises.
>
> The problem never happens on 20M or 10M under any circumstances. I can put a brick on the key at full legal limit on those bands, and the SWR is 1:1 forever.
>
> If I key down full power (actually any power over about 500W) the SWR will be fine for about 20-30 seconds, then will rise (not instantly, but “ramps” up) to about 2.5:1 across the 15M band. If I unkey, kill the amp, then key up barefoot the SWR drops back to 1:1 and stays there forever.
>
> It is as if something heats up under power, then changes value. BUT ONLY ON 15M.
>
> I suspected one of the 15 traps, and hunted down a full new set for a very nice price.
>
> This morning I replaced all of the 15M traps, and freshened up all the slip joints in the antenna. It looks like new!
>
> The problem persists.
>
> Suggestions?
>
> 73, de Hans, K0HB
> --
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