[R-390] Caps and more caps

[Roy Morgan]

At 08:35 PM 1/11/2005, Bob Camp wrote:
>Hi
>
>I must be shopping for my R-390A's at the wrong store.

Bob,

Anywhere you can get one is a good place.  :-)

>...   Electrolytics on the other hand certainly leak,  ... I check ... for 
>both leakage and value. ... I don't worry about the leakage until it's 
>about 5X the specification. I don't see how an extra few ma of current in 
>a power supply bypass cap is going to bother the radio much at all.

I will suggest a reason:

Leakage in an electrolytic filter cap causes heat. Heat is the enemy of 
electrolytic caps, especially the old ones.  The heat generated inside the 
cap will accelerate the degradation of the thing and hasten it's failure.

This is part of the danger of "bringing it up slowly with a variac" 
(without monitoring the reforming/leakage current.)  When an electrolytic 
reaches it's limit of reforming voltage, further increase in applied 
voltage increases the leakage current, the heat goes up and the thing leaks 
even more.  Pow goes your transformer high voltage winding.

Long live your radios.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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