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

[paul swed]

Jared
I took a look at the manual and if you inject 137 hz at .5 Vpp through a 10
Mohm R  thats in a sheild into A7j1 you will see .9 Vpp at TP2 and some
large signal upto 16 Vpp at Yellow out. That would say the A7 module is
good. It looks like the 2 ICs are lm741 class opamps if they happened to be
bad.
Regards
Paul
WB8TSL

On Wed, Nov 24, 2021 at 8:36 AM Jared Cabot via time-nuts <
time-nuts at lists.febo.com> wrote:

> Hi,
>
> Ok, I managed to get a moment to do a few tests. I'll try to answer the
> questions so far, sorry if I miss something out.
>
> For test equipment, I have the following gear of possible use:
> - HP 5335A 200MHz Universal Counter with 1.3GHz option
> - Leo Bodnar GPS Reference
> - HP 34461A Multimeter, just calibrated.
> - Tek TDS748C 1GHz Scope
> - Multiple HP E361xA Power supplies
> - 3325A Function Gen (All options)
> - Many other bits of gear too, including a billion TM500 modules and
> mainframes etc.
>
> On the 5065A front, I have replaced the resistors in the RVFR with
> Mil-spec Vishay RN55, RN60 and RN65 series parts, cleaned the glass
> elements and added a 100 deg.C thermostat to prevent over temperature
> events.
> I have replaced all the wet tantalum capacitors in the entire unit with
> United Chemicon KYB 220uF, 63V capacitors (10,000 hour rated), bypassed
> with C0G/NP0 0.1uF MLCC ceramic caps, there was no PCB damage, but two tant
> caps had just started leaking, luckily not reaching the PCB's.
> I added heat sinks to the two diodes on the A2 board and replaced the RIFA
> mains filter cap too. The 3 big mains filter capacitors tested well within
> spec, with leakage down around 10uA.
>
> - On A8 Pin9, I get 137KHz, 174mV P-P
>
> - A7 TP2 shows me random low amplitude noise
>
> - A3 TP2 I see 5.38VDC
>
> My serial number is 2432A01344 and I have the 10811-60109 OCXO (and no
> options fitted, so the chassis is clean of battery corrosion).
>
>
> Thanks all for the help!
> Jared_______________________________________________
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