[time-nuts] FRSc RB lamp experiment
paulswedb at gmail.com
Sun Feb 13 03:27:24 UTC 2011
Well pretty good news
The lamp voltage went from 1.83 volts a dead bulb to* 8.9 volts a new bulb*.
By adjusting the oscillator I can get to 9.6 volts but I know the the
oscillator will not start correctly at 82 Mhz its happy at 92 Mhz.
Its not locking but that can be due to several issues.
At least 3 grounds are not connected. These are completed by the boards
being mounted on the oven.
The +24 lamp ignition is hanging at +17. So again the grounds or I have a
problem in the lamp regulator. I suspect its the grounds actually. I
disconnected pin 1 into the oven and applied 24 volts when the lamp ignited
manually backed it down to 17volts.
So tomorrow will start to reassemble the boards for correct grounding.
On Sat, Feb 12, 2011 at 7:57 PM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:
> Dear Paul,
> On 13/02/11 00:02, paul swed wrote:
>> Well indeed Magnus the black stuff and silver blob were rb.
>> 300 degrees F for 15 minutes made it all go away.
>> I was using a j thermocouple to measure the temp and right at the bulb.
>> The trick seems to be for a FRS c to get the blob to the lowest point of
>> capsule thats observable. I did this with the normal RB power system
>> to 177 degrees. Gently tapped a few times to get it concentrated.
>> Then powered off and let it cool.
>> Next step hung the assembly from a lamp so the heat gun could be pointed
>> straight up to boil the RB off at 300 degrees for 10 minutes and let it go
>> for 5 more for good luck.
>> The dark area on the capsule is significantly reduced and no trace of the
>> silver blob.
> I had mine go greyish on the first heat-up, but then I cleared it on the
> second run.
> During the heating I could actually see the silver blob shrink.
>> The RB lamp lights well and looks good.
>> Now to try reassembling everything. That will be a job.
> Good news!
> Eager to hear of lock-up results!
> It seems like the normal temperature of the bulb is good for keeping it
> lit, but you need to go further up for the clean-up operation. Maybe this is
> why the grey rubidium-coating didn't rub off for others... they didn't go
> high enough. Still, no extreme temperatures is needed to get the job done.
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