[time-nuts] Dead 5065A - Some comments - Some questions...

[Ulf Kylenfall]

Greetings.

Having had my 5065 disconnected several months
due to all sorts of things, and started it up
yesterday. It was dead. "Pining for the fjords"

No 2nd harmonic. Just PhotoCurrent. Quick Phase Checkusing a scope in X/Y-mode returned a "U" instead of a bump
And most of the rest was noise.

I have previously replaced a number of transistors
in A3 (5 -> 60 MHz Multiplier) during first attempts
to resurrect this unit and it seems like
the rest of them were gone (how come?) now.
Many of them are 1855-0327 which I have replaced 
by 2N4416. Q7 by BC557 (!)
and Q9 by 2N5109. After this, I have adequate regulation
and an AGC of > 4V.

All-in-all: Just about every transistor in A3 was bad.
There were output at first ~ 10 dBm at J8 but it was not
possible to increase the output by tuning. Also
there was no AGC.

I checked a second unit from a scrapped 5065 on my bench
and the situation was the same with that A3. Low output
power. No AGC.

So now for the question before I put any more
energy in trying to fix the rest of the old faithful:

I checked the A1 syntesizer unit which did
provide correct output frequencies but
they were not as stable as the internal
5 MHz Osc. (10811) HP does not mention any
stability/jitter data for A1. Using a 5370B and 1 second
gating, the output fq was stable down to
single kHz figures but jittered further down.
The 5370B counter is locked to a GPS diciplined
105B and comparing with the 5065's internal
10811 (in OpenLoop mode), that oscillator
is also very stable and settable within spec.

I have two of these synthesizers, but they are
both the 1st edition using TO packaged
IC's that are unobtanium. One of my manuals
shows a more modern unit with plastic DIP's.
Some signetics and a one-shot that is unidentifiable.

IF the A1's are bad - has anybody made some
reverse engineering trying to fit the
"DIP-version" with modern available IC's
or modified it in a way that can be reproduced?


Best Regards

Ulf Kylenfall
SM6GXV