Re: LF: TX > RX isolation test

[DK7FC <selberdenken@posteo.de>]

Am 16.07.2018 13:49, schrieb N1BUG:
> I don't know if this is correct but I read that for optimum S/N one
> should have 10 dB noise increase on the antenna when compared to a
> 50 ohm termination.
Yes, 10 dB at least, better more.
What type of preamp are you using (schematic?). For a comparison with 
and without antenna, you need to replace the antenna wire with a 
capacitor of the same C (assume 5...6 pF/m antenna wire, i.e. use 56 pF 
to replace a 10m vertical) connected to the preamp. If this shows as 
e.g. -120 dBfs it should show -105 dBfs with the antennna connected.
73, Stefan