Viking II CDC audio compressor/negative peak limiter

[Edward Cain]

   I know at least a couple of members of the group have or had Viking II CDC's.

   My question is what, if anything, have you done to modify or lose the compressor/peak limiter circuits and why?

   I'm in the middle of recapping mine and wonder if I should be thinking about doing something with these circuits.

Thanks,
Ed/KJ4JST

[KM1H]

Me too. Ive left the audio alone so far as Ive not received any negative reports....yet.

Carl
KM1H

[WA1GFZ]

I left my compressor in the CDC. I just don't hit it too hard.

[Edward Cain]

Thanks for the comments, guys. I guess I'll leave mine alone for the time being.

I have another question, though. Does anyone no what the power rating is for the large, tapped wirewound resistor, R13? For that matter, how about the smaller untapped wirewound right next to it, i.e. R28?

Thanks,
Ed

[KM1H]

Not offhand. Its not in the manual? 

Also go to Mouser or manufacturers site and compare dimensions.

Carl
KM1H

[W1AEX]

Hi Ed,

For some unfortunate reason they did not include the power ratings for those devices in the manual. The smaller 20K (R-28) that is used as a screen dropping resistor for the finals appears to be very similar to some 20 - 25 watt resistors in my junk pile. The larger tapped 20K (sometimes stamped as 25K) resistor that sits across the B+ and provides a voltage divider for the modulator screens is very similar in size to some 50 watt resistors that I have. Those are my best guesses at any rate. It seems that R-13 is very prone to failure, perhaps from the clamp being overtightened or thermal expansion under the clamp.

At the Newington flea market I found an obvious R-13 pull from a Viking, in a box labeled $1.00, and grabbed it because it looked to be in perfect shape. When I got it home and tested it, the thing was open. I should have known better!

73,

Rob W1AEX

[WA1GFZ]

I built a zener shunt regulator using a 20 watt I think it was 20 or 25 Kohms.

[Edward Cain]

Thanks again guys for all the replies. I answered my own question, however, by downloading the assembly manual from BAMA. The power ratings are listed there. Rob was right on the money. R13 is listed as 50 watt and R28 as 20 watt. Mouser has a 50 watt that looks like it will fit perfectly.

Thanks again,
Ed