[time-nuts] HP 5061a synthesizer transistors alternates

[paul swed]

Hello to the group.
Have a recently acquired HP 5061a. The 5 MHz oven oscillator has a short
between the 32V and 18.7V bus. Replaced the oscillator with another. The
synthesizer lost 3 transistors in the phase detector section. One is a
select on test with no number Q20.

Here are the transistors that do work. What I had on hand.
Q17 1854-005 used 2n2222 or a 2n2221
Q18 1854-0035 used 2N3444 same can be used for 1854-0547
Q20 1854-0273 no standard number. Given its job used a 2n5179.
The synthesizer locks up solid at 7.96V and multiple restarts lock.
This is now a spare synthesizer so its not been used in a 5061. But the
scope and 5370 looks very good.

One good thing about all this is because the CS tube had a high current
(not pumped down) the damage was actually minimized as the +3500 ion pump
supply held the CS oven off even with the 32V.
That 5061 is up and operational behaving well.
Now to dig into the crispy oven suspect a shorted heater winding.
Regards
Paul
WB8TSL