UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - "I never got it to work", the story of a £15 PRC320

G6Tanuki · 27th Jun 2020, 7:26 pm

It was kinda methodical - the sort of follow-the-trail-even-if-it-does-not-seem-to-lead-anywhere stuff I tought my techs..

"Why did they do this?" was always a fun game.

The PRC320 in question continues to work well, though I still don't understand its "AM" behaviour.
Officially it's supposed to run a sort-of 'controlled carrier' AM, where the basic carrier-level is varied with a tine-constant of several seconds to follow the audio.

Talk, and the carrier-level rises quickly; stop-talking and the carrier drops-back to save battery-power [plenty of 1950s/1960s ham-radio gear used the same approach]

What seems odd on this particular PRC320 is that yes, talking on 'High Power' AM the carrier slides to follow the audio - but then when I stop talking it ramps-up the carrier to something like 50 Watts, before after a few seconds throttling it back to a more-sensible 'idling 10 Watts DC input'.

I'm not complaining though: working on 80/160M AM I'm regularly complemented on my audio-quality.

27th Jun 2020, 7:26 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: "I never got it to work", the story of a £15 PRC320 It was kinda methodical - the sort of follow-the-trail-even-if-it-does-not-seem-to-lead-anywhere stuff I tought my techs.. "Why did they do this?" was always a fun game. The PRC320 in question continues to work well, though I still don't understand its "AM" behaviour. Officially it's supposed to run a sort-of 'controlled carrier' AM, where the basic carrier-level is varied with a tine-constant of several seconds to follow the audio. Talk, and the carrier-level rises quickly; stop-talking and the carrier drops-back to save battery-power [plenty of 1950s/1960s ham-radio gear used the same approach] What seems odd on this particular PRC320 is that yes, talking on 'High Power' AM the carrier slides to follow the audio - but then when I stop talking it ramps-up the carrier to something like 50 Watts, before after a few seconds throttling it back to a more-sensible 'idling 10 Watts DC input'. I'm not complaining though: working on 80/160M AM I'm regularly complemented on my audio-quality.