[time-nuts] HP 10811A failure
GandalfG8 at aol.com
GandalfG8 at aol.com
Sat Oct 13 20:31:24 UTC 2012
Perhaps a silly question, but as I get the impression that both seem to
have failed simultaneously with the same fault I'm just wondering if you're
sure it isn't what you're checking them with that's developed a problem?
Regards
Nigel
GM8PZR
In a message dated 13/10/2012 13:52:46 GMT Daylight Time, rfnuts at arcor.de
writes:
Hi All,
both of my double oven 10811A's have been running flawlessly until now
when I noticed that the output power has dropped by about 3 dB (measures
only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by
about 20 dB, while the frequency is still spot on.
I used them for various mesurements, so I can unfortunately not remember
what might have caused the failure. Only the 12V linear lab power supply
that fed the heaters had developed a completely dead filter cap, so the
feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear
to be still working though. I'm only using the internal heater. They
draw some 700 mA at power up and drop to around 150 mA each when warm.
So the oscillators are unlikely to be cooked inside. Something must have
happened to the 10 MHz output, possibly an ESD issue?
Before I start taking them apart, can anyone tell what has happened or
what to look for first?
Regards,
Adrian
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