With the idea that I'm not the only one whose 3-500 filaments were coming
unsoldered in contest operation...
I recalled reading a few years ago that someone (W8JI?) theorized that over
time the springs on the filament pins would lose their temper through repeated
cycles of heating, causing the socket to grasp the filament pins less tightly,
leading to higher resistance, more detempering, until temperatures got high
enough to melt the solder out of the pins.
Happily, I discovered that the spring clips are easy to remove and swap, so
what I did was to swap the filament springs for ones that had formerly been on
the grid pins. At the same time I carefully polished the insides of the
filament contacts, as well as the pins themselves, seeking a lower-resistance
connection. Only time will tell...
73, Pete N4ZR
The World HF Contest Station Database
Full details on 3275 contest stations
Updated 1/13/07 http://www.pvrc.org/WCSD/WCSDsearch.htm
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