[ARC5] LM and BC-221 adventures

[Kenneth G. Gordon]

On 21 Feb 2012 at 8:48, Bill Cromwell wrote:

> Hi Ken,
> 
> I had two power supplies that started eating rectifier tubes. Both had
> leakage from the high voltage winding to the 5 volt rectifier filament
> winding and were applying higher voltage across the filaments. The
> transformers were still usable but only with solid state rectifiers
> and the filament supply leads taped off.

Thanks, Bill. I had suspected several different scenarios, but have not yet 
gotten back to that particular unit.

The power transformer is VERY old, like over 50 years old, and quite small to 
boot. Furthermore, I had been running it 24/7/365 in the interests of 
maximum stability and calibration. It didn't run particularly hot, though.

At first, I suspected an intermittant short in the BC-221 itself, but then I 
began to suspect the power supply again.

At this point, my original suspicions concerning the transformer are at the top 
of my list.

I'll dig into it as soon as I have some other projects finished, and will let the 
gang know what I find.

Ken W7EKB