[AMPS] Military Surplus Conversion on VHF amp

Bob & Linda McGraw K4TAX RMcGraw@blomand.net
Wed, 05 Apr 2000 22:18:15 -0500

I've acquired a VHF military amp.  Originally used a pr of 4X150's. 
Presently has a pr of 4CX250B's.  It works!

I'd like to convert it to run a bit of SSB on 2M through it.  As I see
it, the thing needs a regulated bias supply, a change in the control
ckt, and a regulated screen supply in order to run AB2.

The amp is a AM-494 and the psu is a PP-638.  Fortunately I do have
schematics and all military documentation.  The amp was manufactured by
MOTOROLA back in 1953.  This was part of Radio Set AN/TRC-28.

As I see it, I'll remove the 3B28 rectifiers, their sockets, the
filament transformer and replace them with solid state diode units.  The
extra space will be used for a 8 MFD 2500 V filter to make the PSU have
a cap input instead of a choke input.  That should bring the HV up from
1100 to about 1500.

>From there, it's open to suggestions.  As it stands now, 5 watts input
drives it adequately for it to switch over to transmit and output 200 or
so watts.  

Suggestions appreciated.


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