[time-nuts] Re: Turning off display on HP 58503 A or B

[Bob kb8tq]

Hi

Both control loops in the 3801 OCXO’s are thermistor based. If the outside loop 
goes nuts, the device might survive. If the inside loop shorts out, the normal 
result is a melt down of the OCXO innards. 

Bob

> On Jun 2, 2022, at 9:55 AM, K5jv via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> I was recently evolved in a discussion about the HP 58503 option 001 display.  The general idea is that there is some command to tune the display on or off.  A few ideas were offered but no one had anything except "they heard about it."   I have found nothing on the subject from old HP literature.  Comments would be appreciated.  I am not talking about turning the power off to the DC/DC converter.
> 
> On a different subject:  A couple of month back I got some strong criticism about suggesting that the oven in the Z3801A was a potential source of problems.   I just got another Z3801A in for repair.  Same symptoms as before;  appears to turn on normally but after a while goes into holdover and stay there,  same LH flat lines.  Once again the problem turned out to be the oven.  It was unusually hot to the touch.  Changing the oven solved the problem.  Now my question.  I have never opened one of these oven, so have no real idea exactly what is inside.  I would  suspect that one of  the oven's thermostats is stuck in the "on" position.  Since it is a "double oven",  there could be two thermostats?   If these are mechanical contacts, as one might expect fro the 1995 era, can they be cleaned or replaced?   Comments from anyone who has actually seen inside one of these ovens would be appreciated.
> 
> 
> 73 de Lon, K5JV
> 281-795-1335
> 
> 
> [a96323c7-47c0-46b2-8018-f039618476d5]
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe send an email to time-nuts-leave at lists.febo.com