My old room mate, the late Alan McCarthy (AA6GM) bought a video from a
guy back in the midwest who is a Collins repair person. One of the few
factory auth from what I understand. I'm sorry, I've lost his name and
callsign.
The video Alan purchased was for the repair of Collins 30L-1 amplifiers.
I'm told there is a set of videos for the majority of the Collins amateur
line.
A very interesting part of the video is the information given about the
47 ohm resistor(s) in series with each tube path. Alan's 30L-1 used to
eat these resistors for lunch.
In addition to the reduction in gain these resistors provide, a second
less known purpose was to act as a fuse during "problem times". I've
never had a problem with the VHF stability of my amplifier, but Alan had
quite a bit with his. After installing parasitic suppressors, the unit
quit blowing the resistors out.
A final note. The value of resistance and the wattage are both designed
for this "dual function". It was common for persons repairing the
amplifier to use higher watt values and defeating the design feature. We
learned this after doing the mentioned ourselves in his amplifier.
So, the correct size resistors were installed, the parasitics suppressed
and the amplifier never made WAVCR (worked all VCR's).
If any of you would pass along the Name of the guy doing the videos, it
would be nice to know again.
My Jennings catalog arrived yesterday, worth the phone call.
73's
Skip May wv6f
mays@indigo.ucdavis.edu
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