[Milsurplus] Utility Amp Driving Advice.

[Robert Nickels]

On 3/20/2011 1:12 PM, David Stinson wrote:
> I used a Motorola Triton 40S marine SSB rig as the heart
> of a utility linear amplifier
Well Dave, I think you did a heck of a job with it!   Real clever re-use 
of the marine SSB rig (knowing I woulda been up late nights for weeks 
trying to figure out how to reprogram some unobtainium IC in the doggone 
thing ;-)

I can't see any flaw in the basic approach and the on-air and on-scope 
results seem to confirm that you've got a clean signal.

Regarding the protection circuit - assuming you measured the drive on a 
'scope, that's peak-to-peak voltage, and your average RF power is .3535 
times that.   This website does a good job of explaining basic RF power 
measurements than I can do here:
http://www.ab4oj.com/test/pwrmeas.html

Some kind of indicator to let you know how much drive you are applying 
might be a good idea.   As you've stated, you don't want to get even 
close to the diode threshold or you'll have a dandy high level 
mixer-amplifier going!   By the way, that's a nice color choice for the 
front panel too ;-)

I've been having fun with a similar hookup, using my Retro75 2.5 watt AM 
transceiver to drive a Central Electronics 600L broadband linear 
amplifier.   I've got to use an attenuator to keep the output to about 
100 watts carrier to keep the single 813 final happy but it works very well.

73, Bob W9RAN