Hi Antonio, It should run when the ON/OFF switch is ON but not if it's OFF. If the fan runs whenever the power is connected there is a fault, probably a shorted TRIAC. Interestingly on the 5328B they added an RC snubber across the TRIAC which may indicate they had problems with the A model. Alternatively somone may have modified it. The military AN/USM-459 manual still shows the fan as being controlled. The original fan was 35 to 45 CFM (depends on the source of data) so a small 24V DC fan drawing around 100mA should work fine without excessively loading the supply. Any one know a makers part No. or frame size for the original fan? HP don't give these details. I'm assuming it's a 80mm unit but may be wrong as the 5328A is only 89mm high.
Robert G8RPI. ________________________________ From: "[email protected]" <[email protected]> To: [email protected] Sent: Saturday, 18 January 2014, 12:57 Subject: [time-nuts] R: HP 5328A fan - suspected issue I had five 5328A, three military and two normal, and still own three. The fan runs whenever the unit is turned on and never stops. In the military version the fan is much noisy. Antonio I8IOV >Da: [email protected] >Data: 18/01/2014 0.03 >A: <[email protected]> >Ogg: [time-nuts] HP 5328A fan - suspected issue > >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 > > >-- >Mobile: +61 468 512095 >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
