[Milsurplus] Saga of my RAL

[Richard Brunner]

For the amusement of the cognoscenti:
The story starts about a year ago when I acquired an RAL which had been 
stored outdoors face-down in the mud.  First I repainted the front panel 
and box with black crackle, which came out rather well.  Needless to say 
the meters were broken beyond repair.  I replaced all the resistors, 
which were mostly way out of tolerance, and all the mica capacitors 
which were mostly leaky.  The oil and paper caps were all good.  I also 
deleted the plate to ground capacitors in the audio stages to extend 
audio frequency response, but found the audio distorted; by and by I 
found 33 volts of supersonic oscillation on the 'phones which I couldn't 
hear.  This was due to the improved frequency response and about five or 
six feet of unshielded low-level audio wiring.  I shielded the audio 
wiring with braid from RG-58, and the oscillation dropped to 17 volts. 
It was still oscillating because of proximity of audio wiring on the 
filter selector switches and the 41 audio output tube, so I added a 
shield to the 41 and it stopped.  Then followed a long sporadic period 
of tracing crackling noises.  I had to clean all the pots, and replace 
the detector grid leak capacitor four times.  The original was leaky and 
was replaced by an old silver-mica, which soon leaked.  It was replaced 
with a capacitor pried from an old board, which also soon leaked.  The 
third was a new capacitor, and it soon leaked.  Hopefully the new new 
one remains good.

At the end I found a low-level hum picked up in the detector, so I took 
out the ballast tube socket and 200 Watt resistor in the power supply 
and built in a regulated dc supply for the heaters.  It could be easily 
restored, but I cannot think why anyone would want to...  Now there is 
no hum whatever, and the set is singing sweetly.  Was it worth it?  Yes, 
success makes everything worthwhile, besides, I enjoy hopeless challenges.

Richard Brunner, AA1P