[AMPS] Military Surplus Conversion on VHF amp
Bob & Linda McGraw K4TAX
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
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