I've got another ham's Ten-Tec 444 amp on the bench,
with the supplied 444S power supply. The RF circuitry
seems to be behaving; initial results show 550 watts
out with 70 watts of drive. But it trips itself into
standby quite readily; doing so, in fact, after simply
being turned on and allowed to idle for five seconds.
I'm suspecting the power supply pass transistors have
shorted and it's delivering excess voltage, causing
the RF deck to fault. Regrettably, the manual gives
two different sets of "normal" readings for DC
voltages on the thing. The front-panel meter shows
53VDC. The manual indicates in one place that 45VDC
is correct, and in another place, suggests that 55VDC
is correct, and that there's an "overvoltage protect"
at 56VDC. Further supporting evidence is that on the
occasion that I can get it into the transmit condition
with 500 watts out, I can simply hold it key-down for
lengthy periods - and the collector voltage has, at
that point, sagged to some 50VDC.
Does someone have a functioning 444 and 444S who can
provide me with some front-panel and/or DVM-validated
DC readings?
TIA,
73,
Dave W8NF
Helvetia, Oregon
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