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

[Jared Cabot]

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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> 

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