[Amps] Tube Upgrade for Motorola 2 Meter Amp

[Al Waller]

Steve,

The juice may not be worth the squeezing.  Ideal amp would be a 3cx800a7 at
that plate voltage but the old Class "C" power supply would be rather poor
in SSB service so at a minimum new plate transformer and more capacitors in
the power supply.  3cx800 is a triode so you can scrap the screen supply.
Good Luck with the project.

Al

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Steve Berg
Sent: Saturday, August 23, 2008 6:38 PM
To: amps at contesting.com
Subject: Re: [Amps] Tube Upgrade for Motorola 2 Meter Amp

Years ago when I was a service tech, my boss gave me a really nice 1963 
vintage Motorola 1 range tube type quarter kilowatt station.  The final 
deck uses a pair of 4-125 tetrodes in push pull configuration.  As I 
recall, the plate supply is about 2200 volts.  If I were to convert this 
to class AB1, and regulate the screen voltage, I would get barely enough 
power to be noticeably louder than my 160 watt Mirage brick.  I would 
like to figure out some way to make this into a usable 2 meter weak 
signal amp.  The tuned input and output lines are there, but I need 
better tubes.  What sort of changes might I consider to get this clunker 
back on the air where it belongs?

Steve WA9JML
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