[R-390] Rats - There goes a pair of 26Z5W's

[Barry]

I suppose that wasn't the case.  I popped in my other set of 26Z5W's and it
seemed to be okay.  The filter caps are rebuilt so I suppose they withstand
the increased B+ and they don't leak quite as much as the originals did.  I
still think I shorted the PTO can to something - probably the rectified 25V
on the selenium rectifier, but I don't see how that would have blown the
26Z5W's.  Oh well.  It gives me something else to buy...

Thanks,

Barry - N4BUQ

----- Original Message -----
From: "David Wise" <David_Wise at Phoenix.com>
To: "R-390A Receiver List" <r-390 at mailman.qth.net>
Sent: Monday, April 18, 2005 6:59 PM
Subject: RE: [R-390] Rats - There goes a pair of 26Z5W's


Probably blew up the filter caps.  B+ rises in Standby because
the load is smaller.  If the caps were old and used to the nominal
B+, they would conduct greatly increased leakage current
when it was high.  As they warm up due to the increased
power dissipation they leak more.  Hotter, hotter,... SHORT!
Better check them before you replace the rectifiers.

73,
Dave Wise

> From: Barry [mailto:N4BUQ at aol.com]
>
> simply been the tube's time to go.  I had inadvertently left
> the radio in
> STDBY for about an hour and a half while the PTO was warming
> up for the test
> (meant to switch to AGC but forgot).  Perhaps this placed
> some sort of odd
> strain on the rectifiers.  I don't know.
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