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Old March 24th 07, 08:48 PM posted to rec.radio.amateur.boatanchors
Scott Dorsey Scott Dorsey is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 774
Default Question re TL 922 amplifier

Antonio Vernucci wrote:
A second option exists. When you first power up the 922 don't panic over the
current being drawn and jump to turn it off. Wait for 10 to 15 seconds to see
if the filament heating and resultant thermal expansion will eliminate the
short for you.


Very dangerous with the TL-922. Due to Kenwood design fault, the 80V service
voltage gets shorted to ground when a grid-to-filaments occurs. After a short
while the service transformer (T2) will be permantly damaged.


Agreed. However, sometimes shock and vibration can rattle the whiskers
off the grids. Pull the tubes and let them roll around on the floor of
your car for a couple weeks; this may help you get a little more lifetime
out of them.

Be really careful with the things, though.... the transformer damage issue is a
big deal.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."