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

wa3frp at aol.com wa3frp at aol.com
Tue Aug 19 18:45:02 EDT 2008

Hi Ed,

Thanks for your time and your great suggestion. At this point, I think 
that the suggestion to use the Tempco thermoswitch will be the best way 
to preserve the original design of the inner oven and easiest to 
reverse should an exact replacement Princo thermoswitch become 
available in the future.

Best Regards,


-----Original Message-----
From: Ed Palmer <ed_palmer at sasktel.net>
To: time-nuts at febo.com
Sent: Tue, 19 Aug 2008 4:00 pm
Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard - Need 


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 
do a 'return to original state' restoration, at least it would allow 
to have a working system while you wait for something better to show up.


> 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 
> and #2 and any opinions on a source for #3.
> Thanks
> Russ WA3FRP

time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
and follow the instructions there.

More information about the time-nuts mailing list