[time-nuts] HP 5065A rubidium lifetime

Chuck Harris cfharris at erols.com
Sat Mar 20 04:57:42 UTC 2010


When my 5065A had its oven failure, it got so hot that it melted all of the
solder joints on the lamp board.  I resoldered the joints, rewound the oven
winding, and foamed the unit with some spray can urethane (Great Stuff), and
had it working again for a couple of years.  Then something else failed.

I'd sure like to fix it, but Scott McGrath, representing himself as an
employee of Harvard University, borrowed my manual more than a year ago,
and refuses to return it.  Oh well!

-Chuck Harris

John Miles wrote:
> One big favor you can do your 5065A is to check the ESR of the electrolytics
> on the A11 oven driver board.  C23 and C24 were open on mine, as was the
> other instance of the same 20 uF cap on the battery-charger board, and the
> lamp driver assembly had experienced overheating to a point that was
> sufficient to char a resistor and crack it open.  I'm not sure how, or if,
> those two caps would cause total control-loop failure, but there was
> apparently nothing else wrong with this unit that could explain the
> overheating.
> 
> -- john, KE5FX




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