UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Sparky67 · 29th Oct 2020, 4:14 pm

Thanks all.

I do have some voltage readings either side of R62 sent to me by another owner, so have some info on what volts are needed for AGC action. Knowing the 4021 series uses the same AGC circuit is also useful. I did wonder how the PRC320 and VRC321 achieve the same thing, and whether that method could be adopted. No doubt there are a few other HF radio circuits to peruse too!

Yes, the Plessey building-block chips do look like they might provide AGC for this set, thanks. I may also pull the thick film and see if there is a possibility of getting into it.

I have just joined the Racal group on Groups.io and will have a search through their posts this evening.

Thanks again

Martin

29th Oct 2020, 4:14 pm	#7
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 589	Re: Racal VRM4156 AGC Fault Thanks all. I do have some voltage readings either side of R62 sent to me by another owner, so have some info on what volts are needed for AGC action. Knowing the 4021 series uses the same AGC circuit is also useful. I did wonder how the PRC320 and VRC321 achieve the same thing, and whether that method could be adopted. No doubt there are a few other HF radio circuits to peruse too! Yes, the Plessey building-block chips do look like they might provide AGC for this set, thanks. I may also pull the thick film and see if there is a possibility of getting into it. I have just joined the Racal group on Groups.io and will have a search through their posts this evening. Thanks again Martin