C12 and C15 on the support board are for peaking the multiplier/amplifier
for the external standard input. The unit accepts 1MHz, 5MHz or 10MHz for
the external reference frequency. The capacitors tune the external input to
10MHz for the counter to use as the reference.
Cheers,
Dave M
Alberto di Bene wrote:
On 2019-07-23 13:01, Charles Steinmetz wrote:
The later HP5328 "oscillator helper" boards have EFC pots for fine
tuning the timebase frequency. This includes the US military
versions that are so prevalent in the US. I have schematics showing
this with both the 10544 (support board 05328-60027) and 10811
(support board 05328-60038) oscillators (production shifted from the
10544 to the 10811 during the 5328's run).
I found on the surplus market a board with a 10811-60111 OCXO. The
board is marked 5328-20027. I suppose it is for the HP5328 counter.
There is a trimmer marked "Fine Adjust" and two capacitor trimmers
marked C12 and C15. I suppose the "Fine Adjust" trimmer is for the EFC,
but don't quite
understand what those C12 and C12 trimmers are for...
Anybody knows ? Is there any schematics of this board lying around ?
Thanks.
73 Alberto I2PHD
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