[time-nuts] HP 5065A rubidium lifetime

[Bill Hawkins]

Chuck,

How did you get to the bulb?

I thought the RVFR was a sealed assembly.

Bill Hawkins
 

-----Original Message-----
From: Chuck Harris
Sent: Saturday, March 20, 2010 7:52 AM

The bulb on my HP5065A was silver gray in color when I had it out
of the oven.  It still had plenty of output to make the system work.

-Chuck Harris

Bill Hawkins wrote:
> Corby,
> 
> What I meant by "darkening" was that the photocell current and the
> second harmonic were at half of their minimum value given in the manual.
> I don't know what happens in the RVFR to cause that.
> 
> Why would a clear bulb have a low output? Can you refer me to something
> to read? I haven't found the right words to get Google to reveal any
> useful links.
> 
> Several years after I bought the 5065 in 2003, there was not enough
> second harmonic to maintain control, saturating the integrator. So I
> followed the cure for cell flooding given in the manual. After 10 days
> the second harmonic stopped improving at about 10 on the meter.
> 
> Something appears to be microphonic in the photocell. A sharp tap to
> the case causes the second harmonic to peg the meter briefly. A Tracor
> 308 does something similar, but it doesn't have a meter for anything
> but error - the red Unlocked light comes on briefly.
> 
> Perhaps my brain is darkening with age . . .
> 
> Bill Hawkins