[Hallicrafters] High voltage capacitor source?

[Rodger]

Skip,

The original power supply caps in your S-36A are oil type units and are 
very reliable.  Unless you have evidence that they are bad, I would not 
replace them just because they are old.  Unlike electrolytic caps, most 
of the oil filled units of this type are going to be fine still.  I have 
several older mil spec receivers, including a couple of S-36A's,  
running with their original oil units.

If your S-36A is one of the commonly found units built for the Navy, 
then it has an extra acorn tube in the front end that was meant to be a 
radiation suppressor.  This extra first stage is untuned and reduces the 
sensitivity more than 10 db so if you find that yours contains this 
extra stage I would remove the tube and bypass this stage.  If you find 
excessive distortion on FM along with difficulty aligning the FM 
discriminator, then suspect fixed capacitors C29, C74, and C75 which are 
located in the discriminator "can".  Leakage in any of these will create 
problems with poor FM detection.  You should align the discriminator 
after at least a 10 minute warm up and you will find that it takes a few 
minutes for subsequent start-ups for the FM detector to work at its best.

Properly set up, the S-36A does a great job on FM broadcast.  The 
de-emphasis isn't correct for "modern" FM standards but can be changed 
if you wish.  R42 and C32 are the de-emphasis network and are set up for 
the old standard instead of the current 75 uS standard but you will 
probably be happy with the stock value.

73, Rodger WQ9E

Waldo Magnuson wrote:
> I'm in need of a few 650 v.d.c. capacitors (4 uf and 8 uf) for the  
> power supply section in my S-36A.  Where/who is a good source?  Most  
> sources end at 400 or 500 volts.
> Thanks.
> 73,  Skip  W7WGM
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