[time-nuts] HP-5065a advise and purchase decision

J. L. Trantham jltran at att.net
Sat Jun 30 15:30:57 UTC 2012


Edgardo,

The 5065A is a great unit but the price is over the top for a questionable
unit.  If fully meeting specs, the price is still very high, IMO.

The observations you report are likely simple repairs.

The great unknown is whether it will 'lock' or not?  That is to say will the
Continuous Operation light come on?  The 'ovens' all typically go full scale
pegged when initially turned on then come down 'on scale' when warm.  Photo
I will be 0 then come up as the lamp warms up.  2nd Harmonic comes up as the
Rubidium Vapor Frequency Reference unit warms up.  Once things are on scale,
switch from Loop Open to Oper, push the Logic Reset button and the
Continuous Operation light should come on, assuming the 5 MHz oscillator is
close to being on frequency.

Also, the indicator lamps are commonly burned out or the lenses are missing.
There are easy to replace indicators that use the same bulb that you can
install in place of the lamp assemblies if needed.  I can send you the part
numbers for these if needed.


Hope this helps.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Edgardo Molina
Sent: Saturday, June 30, 2012 1:27 AM
To: time-nuts at febo.com
Subject: [time-nuts] HP-5065a advise and purchase decision

Dear Group,

Good morning. I wish you well. This is my first post to the Time-Nuts  
group. Please be gentle with the newbie ;)

I have been offered an HP 5065a Rubidium Frequency Standard recently  
in what I feel, a bad operational condition. I need a reliable  
rubidium standard for my time/frequency experiments, still I am in  
doubt to invest in buying such and old beast. The general situation of  
the instrument (for what I have been able to see from the first  
inspection) is:

100 Khz output: Not working, noise coming out of it.

1Mhz output: Working, sine wave clean and not distorted, a couple of  
frequency meters showing 1.0000030 Mhz in frequency, the oscilloscope  
shows a transient pulse on top of the sine wave signal and affecting  
the frequency readout instantly and then returning to the value  
previously mentioned. Last digits vary sporadically.

5Mhz output: Working. sine wave clean but a little bit distorted when  
ramping up. A couple of frequency counters showing 5.0000014 Mhz in  
frequency. No transient pulses or other glitches around the output  
signal. Last digits vary sporadically.

No lights coming up when the instrument turned on. No physical damage  
of abuse on case or internal components. No options installed . A  
couple of electrolytic caps replaced on some boards, no trace of burnt  
PCB traces or visible damage to electronic components or physics  
package. Haven't got the manual until today and was unable to check on  
the front panel voltages to check on general health. As turning the  
voltage test selector knob, voltage is shown for most positions,  
except of course battery and the 100 Khz oscillator output. Some  
voltage test positions get the instrument needle to go full scale and  
out of range, other appear to be within scale.

I can perform a second visual and operational inspection today, this  
time with a copy of the instrument manual. I will take my own trusted  
frequency counter and portable digital storage oscilloscope. Would  
really appreciate if I could receive comments from you experts to  
evaluate if such a unit could be worth buying. The asking price is $1K  
USD. Should I consider it an instrument that can be repaired and  
serviced to show some decent performance? Or should I look somewhere  
else to get a decent rubidium frequency standard.

Thank you beforehand for all your kind and expert comments.


Respectfully,



Edgardo Molina
Mexico City, Mexico



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