[time-nuts] Re: HP 5065A, no 2nd harmonic.

[Bob kb8tq]

Hi

Quick and dirty way to check the oven is to monitor current. It should start out
near the max rated power and drop back after a few minutes. 

Bob

> On Nov 30, 2021, at 9:36 AM, Jared Cabot via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Ok, so I carefully dismantled the OCXO and I may have found the culprit... The screws holding the two transistors to the metal body were both less than finger tight!
> Don't know how that happened, so they were cinched up to 5in-lbs with the torque screwdriver as per the service manual, and I'll give the thing a test once it's all back together.
> I'll have a dig around to see if I can find a small thermocouple or similar to see what the oven temperature is at now.
> 
> Also, I noticed that a 2.0uF, 20% film capacitor in there is looking like it's had a bit of heat-stroke.
> It measures 2.119uF, 0.22ohm ESR, with a dissipation of 0.004 @ 40V, @ 1kHz, so it seems to test ok.
> Does this look like it needs to be replaced (picture link below)? I can't find the same part on Digikey/Mouser, but it seems like Keysight have them as 'orderable' status.
> Details are as follows: P/N: 0160-4947 Part Description: Capacitor-Fixed 2uF +-20PCT 50V polyester metallized THT
> 
> https://i.imgur.com/aZ0KUD8.jpg
> 
> Thanks!
> Jared
> 
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> 
> On Monday, November 29th, 2021 at 06:30, <cdelect at juno.com> wrote:
> 
>> With that offset either the oven set point has changed or there has een a
>> 
> 
>> component value shift in the oscillator circuit.
>> 
> 
>> The easiest way to test is to stick in another 10811 if available.
>> 
> 
>> You could also install one of the original 105 style oscillators if you
>> 
> 
>> have one.
>> 
> 
>> Cheers,
>> 
> 
>> Corby
>> 
> 
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