Re: LF: WSPR-15 last night

[DK7FC <selberdenken@posteo.de>]

Am 20.11.2018 13:44, schrieb N1BUG:
> I will look around for the box which contains
> that project, maybe I can easily put it back to its original form...
> if the cat didn't find the box and take too many parts!
>    
There are really many OMs having cats! Joe has one, Markus had one, i 
think M0FMT has one and others. Should i also buy one?
Sorry, OT stuff. Anyway, can you tell me her name? I'm always searching 
for new EbNaut messages!...
> OK, thanks for the ideas. I did notice last night something
> interesting on MF. The phase was changing slightly during each TX
> period. Something to note is that on MF, the coax to the antenna is
> almost exactly 1/8 lambda electrical length. So any change in
> antenna R shows up mainly as a change in phase at the transmitter.
>
> So it may be that something in the antenna is changing R on MF also
> (with only ~75 watts RF). It's a completely different coil and
> transformer so what could it be. I don't know.
>    
There are many possible reasons. Another one: The coil becomes warm and 
this leads to a higher coil diameter and thus a larger L. Then the 
resonance frequency drops and the phase will change. But this will not 
lower the resistive component, usually.
73, Stefan