[time-nuts] Using HP5071A with dead tube along with GPS

[vilgotch1 at gmail.com]

I have done this with an older 5061A that still has a good Cs tube but I
don't want to use it too much.

I used a Brooks Shera kit and a Trimble Lassen IQ receiver and fitted it all
into the empty battery compartment. With a bit of modification it was
possible to retain the Cs function but run it as a GPSDO when the Cs is
switched off. I had to determine the VXO characteristics as described in the
original Shera article and fitted a separate opamp to set the loop gain.
Once there's a GPS receiver in there it's a shame to waste the time output
so I also fitted a microcontroller to translate the output code to IRIG-B
for an external time display. It has worked very well for several years now.
The Shera kits are probably not available any more but there are many others
that could be used. 

Good luck!

Morris


-----------------------------------------------------------
Subject: [time-nuts] Using HP5071A with dead tube along with GPS

I can't quite remember who gave me this idea...? but I'm pretty sure he was
a member of this mailing list.
I have an HP5071A high performance version with a dead tube.? But rest of
the unit, as far as I know, works just fine.? I know it has a PPS INPUT on
it.? I also know it has a very good OCXO in that, too.? Would it be possible
to steer this OCXO using GPS when Cs tube is completely dead and unlocked??
I do not want to take this apart, just in case nice usable tube lands in my
hand in future.
The reason I ask...? I can just do it and see, but I have no way to verify
the performance.? I have an old Cs with no characterization, and rest are
Rbs and T-bolts.? Seems like what I propose would result in OCXO pulled by
two different servos.? (and even if the results were awful, I wouldn't know
it)

Happy holidays!

---------------------------------------
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG