Very interesting about reversing the bottom plate, but I wouldn't do
this. The holes are where they are to cool the transformer. If you have
trouble with insufficient cooling, replace the fan with a more powerful
one.
The stock fan in my never-used TL922 was super-quiet, but I was
uncomfortable that it wasn't blowing enough air, so I replaced it. Check
the springs in the socket to be sure they haven't been weakened by
excessive heat and switch them with springs from the grid pins if they
aren't tight.
The one mod that I recommend is replacing the antenna relay with a pair
of fast relays. Even if you never operate QSK, the stock relay is too
slow for semi-QSK and will hot-switch.
I believe there is also a mod to prevent a grid-filament short in one of
the tubes from taking out the transformer. I didn't do this because my
QSK arrangement took acare of it), but I would search for it.
73,
Vic, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
On 25 Oct 2016 13:25, Steve Wright wrote:
On 25/10/16 15:28, Jeff Breitner <lists@rudn.com> wrote:
I'd like to get some opinions/thoughts on bringing back into operation a
TL-922a that I recently acquired. The unit sat for at least 15 years
in an
attic. I don't think it has many hours on it. Which of course may
mean,
it is broken.
Switch to CW and fire it up. If you were really worried about it - then
start it up on the variac at 75% input volts, and bring it up to full
mains input over an hour or so.
If you were really worried about a fault, then switch the amp on first -
then switch on at the wall plate. That might save you sourcing a new
switch for it.
Leave it idling there for a day, then ground the PTT input for just a
second and see if you have any idle IP. If so, I'd just use it for an
evening with about 25 watts drive. If it worked fine for a couple hours
with no cranky stuff, then I'd switch mode to SSB and tune it up at
maximum drive and just use it.
If the panel meters are still lit then it hasn't had any work at all.
There is only one mandatory mod, and that is remove the bottom panel and
swap it end-for-end, so the holes are under the tube sockets. If you
don't do this, the solder will melt in the tube pins and drop out -
after this mod there were no issues. Two screws wont fit the panel now
- I just left them out.
Steve
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