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Re: Topband: Slightly OT - amplifier noise

To: Topband <topband@contesting.com>
Subject: Re: Topband: Slightly OT - amplifier noise
From: Steve London <n2icarrl@gmail.com>
Reply-to: n2ic@arrl.net
Date: Mon, 16 Mar 2020 10:47:09 -0600
List-post: <mailto:topband@contesting.com>
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
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