[time-nuts] Restoring GR 1120-AB Frequency Standard

[phil]

Gentlemen,
Original poster is trying to "RESTORE" this entire old General Radio 
Standard ( a rack of equipment) to it's "original" glory.
He simply needs a part, a unique thermoswitch or a way to fix it, not 
retrofit an atomic engine! This is a museum class instrument, 100kc.

May I suggest start a new thread on the better/best merits/design of 
temperature control.
Makes it rather difficult to follow a thread as the subject has changed.
Respectfully
Phil



----- Original Message ----- 
From: "Mike Monett" <XDE-L2G3 at myamail.com>
To: <time-nuts at febo.com>
Sent: Friday, August 22, 2008 9:20 AM
Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard


>
>  Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
>
>  >  Max
>
>  > A capacitance  bridge  using  a transformer would  be  a  lot more
>  > stable than merely using the capacitance to vary the  frequency of
>  > an LC oscillator.
>
>  > The advantage of a capacitive sensing technique over a  light beam
>  > is that it has much simpler and potentially more stable mechanical
>  > system than when a the mercury colum interrupts a light beam.
>
>  > Unless of course on has the Mercury column move a moire grating or
>  > similar setup  such  as  making the top of  the  mercury  column a
>  > reflector in an interferometer system.
>
>  >  Bruce
>
>  Very clever! According to this web page, interferometry could give a
>  resolution of 0.15 nm, or close to the radius of a silver atom:
>
>  http://www.aerotech.com/products/engref/intexe.html
>
>  This video  shows the basic principle in case you want to  make your
>  own:
>
>
> http://www.metacafe.com/watch/1381543/laser_interferometer_homemade_for_20/
>
>  You can  see  from  the   movement   of  the  fringes  how sensitive
>  interferometry can  be. This should  give  unprecedented temperature
>  control, so maybe someone has already done it. A google search gives
>  lots of hits, but it is difficult to distinguish between controlling
>  the termperature of something, and the need for accurate  control of
>  temperature to get stable fringes!
>
>  Great idea!
>
>  Regards,
>
>  Mike Monett
>
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