[time-nuts] HP5071A with bad tube.... can I get one used?

[Tom Van Baak]

Taka,

The chance of finding a cheap, used, working, replacement tube is rather 
small. But...

1) One approach is keep looking for another 5071A that's not working and 
selling cheap and hope very much that it's just the electronics that's 
bad and the tube is still good. Then you can create one working standard 
from a combination of parts; a time nut right of passage.

Some years ago Corby had success retrofitting old "skinny" tubes from 
5061B into 5071A frames. But that requires a working, surplus, late 
model 5061B tube, which is also about as hard to find as a 5071A tube.

2) Or, you can remove the dead Cs tube (to save weight) and simply use 
the 5071A as a stand-alone quartz frequency standard. Besides a very 
nice 10811 oscillator you get lots of nice features, including redundant 
120 VAC and 24 VDC power inputs, internal battery backup, 5/10 MHz 
outputs, 1PPS outputs, optional 1PPS sync, coarse phase stepping and 
fine frequency steering via SCPI commands over RS232, a nice looking LED 
time display, and an LCD with keyboard.

None of this requires so much as a screwdriver or soldering iron. Note 
that using a PC or Arduino and talking SCPI could turn it into the most 
over-the-top alarm clock.

3) Still another idea is to turn the 5071A into a GPSDO. Hey, maybe call 
it the 5071G. Yes, you'd have to add a GPS/1PPS receiver and some sort 
of phase comparator or time interval counter (e.g., TAPR/TICC) and 
microcontroller. But, no, you wouldn't need any of the usual GPSDO DAC 
and EFC stuff since the 5071A already contains a fancy DDS with much 
better resolution and stability than anything inside a traditional 
GPSDO. There's plenty of space for your circuits with once the dead Cs 
tube is removed.

4) Last option is to part the 5071A out. There are people on the list 
who might be interested in select pieces, or even the whole...

/tvb


On 10/23/2019 8:42 PM, Taka Kamiya via time-nuts wrote:
> I have an HP5071A with a high performance option that does not work.  All of my tests indicate the faulty component is a tube itself.  Buying a new tube is way out of my budget.  I am now torn between parting it out and see what I can use and keeping it intact with hope something might pop up.
>
> Question for the group....  Obtaining a used tube for this, I don't care if its high performance or not, as long as it works with the chassis, is really not a possibility, correct?  I have never seen one on eBay.
>
> ---------------------------------------
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.