[time-nuts] HP 5061A Problem

[Tom Knox]

If you have another reference like a GPS or Rubidium it makes set up much easier since you simply tune to 5MHz and then adjust current.
The High Perf Tubes often needed to be degaussed, I have the 10638A but no cable if that is any help contact me off list. 
Also placing an external power supply on the ion pump is often needed if the clock has been stored for a long period. 
In the past I could talk you through set up on the phone but now I would need it in front of me, sorry.
Thomas Knox



> Date: Sat, 21 Sep 2013 14:27:38 +0200
> From: rfnuts at arcor.de
> To: time-nuts at febo.com
> Subject: [time-nuts]  HP 5061A Problem
> 
> I got a 5061A with high performance tube that I'm trying to get running.
> 
> The Cs oven works and the -3500 and -2500V are there.
> The beam current has its maximum at the correct frequency.
> 90MHz from the multiplier are there and they are phase modulated with 
> 137Hz at about 0.01 rad.
> Measured on a spectrum analyzer, the 137Hz sidebands are some -47dBc.
> I'm not sure if that low modulaion index is correct though.
> 
> Also, the harmonic generator alignment worked as described in the manual.
> Measured with the EM output into a 10M input DMM, the floor was around 
> -60mV, finally set to some -90mV after alignment.
> The low frequency test worked as well and delivered a maximum at some 
> 41.6kHz.
> 
> An unusual observation is that the meter indicates beam current 
> immediately after switching the CBT on.
> Nevertheless, it could be tuned to the correct maximum after warming up.
> However, there is still no 2nd harmonic and it doesn't lock.
> 
> Measured with a scope directly at the EM output, there is mainly noise 
> with just a faint signal when maxed with the A3 mod level potentiometer.
> 
> Unfortunately, I couldn't find reference data in the manual, neither for 
> the beam current nor the multiplier modulation index.
> 
> So far, everything seems to work properly except for the missing 2nd 
> harmonic and the unusual beam curren behavior.
> 
> Any help would be much appreciated.
> 
> Adrian
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.