[R-390] Capacitor failure

[Charles P. Steinmetz]

Perry wrote:

>[The chance of losing a choke from a bypass cap failure] is why one 
>makes the 3 fuse mod to a R 390A and adds an additional separate 
>fuse to the SP 600 B+ circuit.
>*   *   *
>And the most likely cap to short is not a .01 bypass unit but an electrolytic.

Definitely not true of the SP-600.  The paper bypass caps have proven 
to be hundreds if not thousands of times more failure-prone than the 
electrolytics over these radios' lifetimes.

Also, most choke failures are the result of long-term overheating 
from one or more leaky bypass caps, not a sudden current surge from a 
cap going shorted -- so a fuse that is large enough not to 
nuisance-blow on a properly-working radio may not give much if any protection.

Best regards,

Charles