tubes age 43
> continuous service ratings for greater transient temperatures.
I've been following this thread with quite a bit of interest as I have a large
amount of boatanchor gear here (hopefully soon to include an R-390a. ;-)
I know some here recommend running tube type gear on variacs and leaving it
on all the time; but reducing the voltage when it's not being operated. My
question is with typical tube type ham gear, how much voltage reduction is
normally necessary to help preserve the life of the tubes and gear when it is not
being operated? I would like to extend the life of my tubes, but don't want to
lower the voltage enough to cause damage to the cathodes of the tubes.
In a slightly different but related subject, I am also looking at adding inrush
limiters to my tube type gear to help extend the life of the tubes by limiting the
turn on current and allowing them to come up slowly. I believe some here have
also experimented with this in lieu of ballast tubes and had success.
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Date: Thu, 17 Aug 2000 04:50:31 -0500
Subject: [R-390] 15.8K hours and it broke...
About the end of the second week of October of 1998 I finished my overhaul of
an all original and very low mileage 1967 EAC. Well, after better than 15,800
hours of 24 and 7 operation since I overhauled the beast, it puked a little while
ago. This is the first time it actually quit working.
Symptoms? Reception just faded into oblivion over a few seconds.
The receiver had plenty of audio power but no RF. No signal from the calibrator
either. I slid it out of the rack and pulled the two top covers and plugged it back
in. The 6DC6 didn't light up so I stuffed another one in. That did it and it came
back to life so I reinstalled the top covers and slid it back into the rack where it's
playing as I type this. It didn't even cool off since the total repair time was under
four minutes. :-)
For what it's worth, that particular 6DC6 was replaced last November so it only
lasted about 6500 hours before the filament opened up.
In over 15,800 hours of operation, I've experienced a total of two "operational
problems" with this receiver. Both of which were corrected by tube
replacements, first after 13 months of operation and just now after 22 months
of operation.
I've had to replace a grand total of 5 tubes, two 6DC6's, a 5814A, a 5654, and a
6C4W. Not too shabby for almost two years of constant operation sitting in an
open rack in a non climate controlled environment where the humidity regularly
(14 pages)
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