I'll stick my neck out and suggest Dallas Lankford's '2 FET amp'.
He designed it for phased loop antennas for the MW band.
I believe it will work to at least to 9 MHz and maybe to 30 MHz.
The specs High input Z, ~100 ohm output Z. He lists input intercepts:
IIP2 = ~ +88dbm and IIP3 = ~+41dbm in the MW band.
The webpage has some noise measurements on pages 3, 4, and 5 that
were over my head.
This page has more than just his amp but enough so you can
understand it.
If anyone has an interest, I have some more files in my computer.
https://www.okdxf.eu/lankford/Hi%20Z%20PPL%20Loop%20And%20Flag%20Arrays.pdf
I have a plan to put a matching transformer and a Hi Z amp on my
antenna with relay switching,
so I can do a real A, B, comparison. If you have any advice on
implementing that or advice about
common mode filtering, I'm listening. Better relay suggestions would
be appreciated.
Mikek KF4ITA
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband
Reflector