[time-nuts] Restoring GR 1120-AB Frequency Standard - Need assist...

[Ed Palmer]

Russ,

I don't know what your requirements are for current capacity or 
mounting, but you might be able to find a simple crystal oven that you 
could rob the thermoswitch from.  There are various ones on ebay that 
are 75 C.  With luck, you might find an adjustable one that you could 
tweak to 78 C.

Another thought is to replace the switch with a simple solid-state 
circuit.  Since you'd be replacing an on-off switch, something like a 
thermistor + comparator would be appropriate  Even if you were trying to 
do a 'return to original state' restoration, at least it would allow you 
to have a working system while you wait for something better to show up.

Ed

> Date: Tue, 19 Aug 2008 11:46:56 -0400
> From: wa3frp at aol.com
> Subject: [time-nuts] Restoring GR 1120-AB Frequency Standard - Need
> 	assist...
> To: time-nuts at febo.com
> Message-ID: <8CAD029F1D74F52-1530-4B6 at mblk-d45.sysops.aol.com>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
>
> I am in the last stage of restoring a 1964 General Radio Frequency 
> Standard Model 1120-AB.
>
> I'm having trouble getting the inner oven to work propoerly and the 
> problem has been traced to a defective thermostat in the inner oven.  
> In checking, the thermostat is a thermoswitch manufactured by Princo 
> and is no longer available.
>
> My options appear to be:
>
> 1. locate a working GR Standard Frequency Oscillator (1113-A) and 
> replace the entire chassis.
>
> 2. locate a non-working GR Frequency Oscillator and part it out as 
> needed
>
> 3. find a suitable replacement for the original thermoswitch (78 C - 
> closes circuit when temperature is reached)
>
>
> I was wondering if anyone on this list has any sources or leads for #1 
> and #2 and any opinions on a source for #3.
>
> Thanks
> Russ WA3FRP 
>