[time-nuts] HP 5061A Problem

[cdelect at juno.com]

Adrian,

Most used High stability tubes are DOA but you might get lucky!

You say the low frequency test "worked".

What was the amplitude of the peak in nanoamps and was the peak well
above the noise or baseline level?

Once you were on the peak did you adjust the 41.6Khz amplitude to max the
signal?

Once on the peak you can adjust the mass spec pot on the top of A11 to
peak it.

If the peak was >8na and above noise then the tube appears to be working.

Anything below 4 or 5 na the tube is depleted, might be useable but STS
will be terrible.

If the peak is >8na then reconfigure for normal operation, in open loop
mode.

Turn the mod on and connect a scope to A8 J1 to observe the phase
detector output.

Adjust the fine and or coarse oscillator adjustments back and forth
across 5Mhz.

If you can see any output as you sweep through then set the osc.
frequency to peak the signal.

Then adjust the A3 mod and the A4 (top pot) to peak the signal.

A7 gain will adjust the amplitude.

Adj the osc freq. to null the signal (puts you "on" frequency) and see if
you have any 2nd harmonic now. 

If so go ahead and see if it will lock.

Good Luck!

Corby