Re: R: Re: LF: TXing 2200m WSPR

[DK7FC <selberdenken@posteo.de>]

Hi Paul,

Am 28.12.2017 21:57, schrieb N1BUG:
> It seems the problem must be RF getting into something, RF current 
> where it does not belong, but only when feeding the antenna.
> An important note: There is no such thing as complete isolation of 
> antenna ground from shack AC power ground here. Both towers are 
> grounded for lightning protection, one has an extensive radial field 
> because I shunt feed the tower on 160m.
That can make things even worse, because you have a low impedance closed 
loop then.
As i meant, just build a 1:1 isolation transformer and place it between 
coax and antenna. Take one of the blue cores you took for the 
transformer in the PA, using 2x 10 or 2x 15 turns or so.
Oh and regarding class AB vs. class D PAs: Build a second one in 
class-D. It is no problem to get 100W at 13.8V with your U3. Good enough 
for WSPR, OP32 and of course EbNaut :-)
73, Stefan