[Amps] 3-500Z filament desoldering - sequel

[Pete Smith]

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
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