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Messenger m4v 10m 800w mobile:


This was given to me to repair, but the owner wasn't interested in repair when he got the diagnosis. (all 8
of the 2sc2879 were cooked) So it sat in my pile for several years before I decided to fix it for myself. It's
a 2-stage "CB-grade" HF amplifier that I haven't been brave enough to put on a spectrum analyzer yet. but it
would probably work respectably well with the addition of some inter-stage and output filtering. At least it
uses bias on the transistors, and operates in class-C mode. I suspect the biasing either was adjusted too
high or didn't thermally track properly (or the user used it with too high of a duty cycle) which led to a
thermal-runaway and destruction of the entire second stage. (well, two transistors "survived" but were not
doing full output anymore)

It's pretty power-hungry, running at 12 volts DC. With those finals it should be capable of 800W or more, with
10w or so of drive. Pictures taken on 2013.01.28

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IMG_0395	IMG_0396	IMG_0397	IMG_0398	IMG_0399	IMG_0400

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last updated 05/10/2025 at 21:20:49 by make_www_index.command version 2025.05.08.A