Hi Roughly speaking the OCXO is 40 Hz or 8 ppm at the max end of the tune range. That’s a lot.
If your OCXO is that low, then yes, it is a problem. You either need to repair or replace the OCXO. If you are replacing, the question becomes - do you upgrade to a 10 MHz 10811? That would involve tracking down one of the assemblies that mate up with the 10811. Bob > On Nov 27, 2021, at 12:28 PM, Jared Cabot via time-nuts > <[email protected]> wrote: > > Hi, > I have performed the test with the 10Mohm resistor. > With an 0.5V P-P signal from the function generator into A7J1, I get 980mV at > A7TP2 (Manual says it should be about 0.9V) > When I probe the A7 output (Yellow wire) i get a good output as described in > the manual too, so it looks like my A7 module is ok. > > However, when I plug the RVFR back into A7J1, I get exactly no output from > the A7 module at all. > > Interestingly, the highest I can get the OCXO to adjust using the coarse > adjustment (with the fine adjustment set to 250) is > 4.99996155 MHz, measured using my GPS referenced 5335A connected directly to > P3 on the A10A2 OCXO Frequency Divider/Amplifier Assembly. > > If this isn't close enough to exactly 5MHz, could it be causing a problem? > > > Thanks, > Jared > > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > > On Saturday, November 27th, 2021 at 01:24, paul swed <[email protected]> > wrote: > >> 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 < >> > >> [email protected]> 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_______________________________________________ >>> > >>> time-nuts mailing list -- [email protected] -- To unsubscribe send >>> > >>> an email to [email protected] >>> > >>> To unsubscribe, go to and follow the instructions there. >> > >> time-nuts mailing list -- [email protected] -- To unsubscribe send an >> email to [email protected] >> > >> To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send an > email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
