[time-nuts] HP 5328A fan - suspected issue

[Brett Owen Rees]

Hi all,

This is my first post to this list. I recently acquired three HP 5328A
counters and have been using one in my shack. They all seem to have fan
issues, with the fans not running in two of them and in the third unit a
resistor near the fan starts to smoke if I turn it on. All of the fans look
identical, being 110V AC units.

So, I have some questions:
- should the fan run all of the time or is it on a thermostat
- does the smoking resistor mean that the fan is seized
- can I replace it with a 5V/12V computer fan. If so, can I safely tap DC
off the power supply and will the fan introduce any electrical noise? I am
240V here so sourcing a fan 110V fan locally may be difficult

The counter I have running seems ok without the fan running. It is the pick
of the bunch with the OCXO, 525MHz and DVM option. Being the best
oscillator I have currently, I have checked it against WWV and it seems ok.
I also used it as an alignment  reference for a funcube dongle receiver
(with tcxo) and am receiving WSPR spots on frequency, so I think it is
good. I am slowly getting the time-nuts bug and am building a GPSDO with a
Morion MV89A ocxo ...

Many Thanks es 73
Brett VK6EZ


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