[time-nuts] HP 5065A lamp

[Magnus Danielson]

Dear Corby,

Corby Dawson wrote:
> Bill,
> 
> The receiver unit is not sealed.
> 
> To remove the lamp assy. you remove the two nuts (one inside) and the 3
> shields from the central threaded rod that protrudes from the lamp end.
> 
> Then remove the tiny phillips head screws (3) around the circumference of
> the lamp assy.
> 
> Wiggle a bit and pull straight out.
> 
> If you look thru the honey-combed end you will see the bulb.
> 
> NOTE! when you reassemble the unit the two nuts must be positioned so
> that they clamp tightly against the last shield cap! It is the heat sink
> for the lamp assy!
> 
> Also as to the bulb appearance. A clear bulb can indeed be bad and a
> discolored bulb can be good!
> 
> If enough rubidium gets absorbed into the bulb envelope there won't be
> enough left for proper operation. Bulb can be clear or discolored if this
> happens.
> 
> Also the photo-I indication does not always reflect a bad bulb.
> 
> The photocell responds to all the light from the bulb, but the operation
> of the standard only needs a good output at a very specific frequency
> (7800 angstroms).
> 
> So if the wideband light output is down but the 7800A is good the photo-I
> is low but the RX output is still good!

Good point. It makes perfect sense. Thanks for taking the effort to 
share your experience.

Best Regards,
Magnus