[time-nuts] R&S XSRM Rubidium

paul swed paulswedb at gmail.com
Fri Feb 18 23:26:41 UTC 2011


As the Rb has run for 3 days the light is brightening. Its gained .4 volts
and is at 7.7vdc.
So thats a very good sign I was concerned it might ramp down as it does when
first turned on.
I think several things could be done on the next one that starts to fail.
Check the oscillator components. Why won't is start reliably in the 85 Mhz
region. That would easily add 1 V additional to the lamp.
Still not crazy about the 17/22 volt regulator circuit design and method of
operation clever as it is. I would change it to a 3 term adjustable
regulator and switch in a additional resistor to lower the voltage on lamp
ignition. Also add some hysteresis to that circuit to allow the lamps to
operate further down the brightness curve.

Curious question why even keep the boards surrounding the oven. Given that
we tend to put these things in boxes the boards can be folded out and kept
away from the heat. This would also easily allow all boards to be adjusted
and repaired.
Anyhow I think this wraps this thread up.
Thanks for all of your comments and suggestions along the way.
Regards
Paul
WB8TSL

On Wed, Feb 16, 2011 at 4:26 PM, paul swed <paulswedb at gmail.com> wrote:

> Maybe get a1980s strobe light and some fiber and pipe it in.
> If you read through the thread though indeed the heat gun at 300 degrees
> did recover the rb lamp nicely and I am burning it in for several weeks to
> see if it stays lit or decays.
>
>
> On Wed, Feb 16, 2011 at 2:27 PM, Oz-in-DFW <lists at ozindfw.net> wrote:
>
>> And cold fluorescent tubes.  I can often get my attic fluorescents to
>> start with a bright flashlight applied close to an end.
>>
>> On 1/22/2011 5:05 PM, Bob Camp wrote:
>> > Hi
>> >
>> > Neon bulbs do the same thing. The ignition voltage is light sensitive.
>> If you see a place they are being used as a voltage reference, they get
>> painted black.
>> >
>> > Bob
>> >
>> >
>> > On Jan 22, 2011, at 6:02 PM, WB6BNQ wrote:
>> >
>> >> Paul,
>> >>
>> >> The LED thing is interesting.  Are you sure you were not just seeing a
>> reflection
>> >> of some sort ?
>> >>
>> >> Bill....WB6BNQ
>> >>
>> >> paul swed wrote:
>> >>
>> >>> Other thing, measuring ignition time. On the first run just for the
>> heck of
>> >>> it I flashed a led light into the ampule and it ignited instantly. So
>> >>> perhaps for old hard starting end of life RB lamps this might be a
>> trick to
>> >>> at least get it going for a bit longer.
>> >>
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>> --
>> mailto:oz at ozindfw.net
>> Oz
>> POB 93167
>> Southlake, TX 76092 (Near DFW Airport)
>>
>>
>>
>>
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