[time-nuts] Hydrogen Maser KIT!

Magnus Danielson magnus at rubidium.dyndns.org
Mon Sep 15 16:19:20 EDT 2014

Hi Corby,

Looks like a nice challenge and lots of fun and learning.
A maser or two would not be bad for my lab :)

Those Sigma-Taus is known to be pressure sensitive. Might be something 
to investigate.


On 09/14/2014 07:16 PM, cdelect at juno.com wrote:
> Well, I bet that got your attention!
> My Hydrogen Maser "kit" arrived recently.
> It's a surplus Sigma Tau VLBA-112 with an unknown physics package problem
> that has had its power supply modules, RF receiver modules, synthesizer
> and cavity servo tuning modules, and a couple other "bits" removed for
> spares.
> Also it has been opened up to the level that the storage bulb could be
> removed. (Magnetic shields, insulation, and bell jar removed)
> The two main problems (so far, fingers crossed) are that the palladium
> silver purifier/leak valve is missing (along with the Hydrogen supply
> bottle), and that the storage bulb coating looks to be shot.
> I've been tracing the power supply wiring and design, and should be able
> to replace the missing stuff easily.
> Minor problems are fabricating connectors for the ion pumps, replacing
> one missing oven control module, and finding a Perkin Elmer pump
> controller (150ma) for a reasonable price.
> Once the bulb and purifier problems are cured the  major efforts will be:
> -to reassemble the cavity, shields, and bell jar.
> -bakeout and pumpdown the ion pumps (in isolation)
> -bakeout and pumpdown the system.
> -stabilize the ovens and initiate the Hydrogen discharge.
> Then if oscillation can be achieved the RF system can be built.
> Replacing the Automatic cavity tuning will come last as it's not needed
> for basic operation.
> I plan to add a relay on the input of the EFOS2 Maser that lives here.
> This will allow the EFOS RF systems to be utilized for testing before
> having to build up the new receiver.
> This will be a LONG term effort and I will share the progress as I go
> along.
> Some info:  Copper cavity loaded with Quartz dielectric cylinder and
> Quartz bulb.
>                  Cavity Q (loaded) 36000
>                  Line Q approx 1.6X10+9
>                  Drift < 5 parts in 10-15 per day (Auto tuner on)
>                  Temperature sensitivity < 1 X 10-14 per degree C
>          `        Weight 525 pounds (including backup battery)
> Tom has kindly posted some PIX at: http://leapsecond.com/corby/maser/
> You might want to look at the old posts about homemade Hydrogen Masers
> starting back in Aug 29 2010.
> Cheers,
> Corby
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