[Hallicrafters] PS-500A AC rebuild

[Glen Zook]

Mouser doesn't sell parts kits for amateur radio equipment.  Now you will NOT find the exact capacitor values in modern components.  Capacitor values now follow the same pattern as resistors.  Therefore, you will have to replace the 40 mfd at 450 volt capacitors with 47 mfd, the 50 mfd at 150 volt capacitor with a 47 mfd at 160 volts, and the 20 mfd at 450 volt with a 22 mfd at 450 volts.  Remember that the old capacitors often had a tolerance of - 50% / + 80% and therefore they actually range all over the place.  There are new capacitors available at very reasonable cost from Mouser and other suppliers and those capacitors have a tolerance of +/- 20%.  Therefore, the new capacitors will be much more likely to be closer to the original design values than the old ones were when new.

Also, modern capacitors are generally between 20% and 30% of the size of the original capacitors.

Modern diodes are also smaller than the originals and are available in higher voltage ratings and higher current ratings.  I would just replace them with diodes that have both a higher voltage rating and a higher current rating.  Again, new diodes are very cheap from Mouser and other suppliers.

Glen, K9STH

Website:  http://k9sth.com


--- On Sun, 11/23/08, Tom McDaris <ab8bw1 at chartermi.net> wrote:

From: Tom McDaris <ab8bw1 at chartermi.net>

I recently acquired a very nice SR-400A and plan to keep it so I am interested in going through the power supply.  All is fine now but I consider it a good idea to replace those 38 year old diodes and capacitors.  Does anybody sell a kit with all the required parts like they do for the Collins stuff?  I checked Mouser and found nothing.  Any suggestions would be appreciated.