Lankford's stuff works great. I have used his antenna which does NOT use a preamp.....it's only suitable for situations where match to the feedline isn't critical, but it sure is great to not have any preamp outside.
de K8RYU ________________________________ From: Topband <[email protected]> on behalf of Mikek <[email protected]> Sent: Thursday, March 12, 2020 7:29 PM To: [email protected] <[email protected]> Subject: Topband: Hi Z amplifiers for 160m 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 _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
