Topband: Slightly OT - amplifier noise

[Steve London]

This has been a very interesting thread - Thanks for all the input.

Perhaps I have set my expectations too high.

A typical application is on 15 meters, late in the opening, working JA's from 
here in SW New Mexico. Absent any local QRN, the band is very quiet. Any local 
noise covers the bottom layer of 5 watt JA's calling me.

I did some more testing with the MFJ-1025. With no antennas connected, the box 
raises the noise floor about 10 dB, irrespective of the Aux Antenna Gain or the 
Main Antenna Gain. I haven't yet tried powering from a battery, to make sure the 
power supply isn't the source. Assuming the J310's are quiet, that leaves the 
2N5109 emitter follower, or the back-to-back protection diodes. Might also try 
disconnecting the RF sense circuit.

73,
Steve, N2IC