[time-nuts] Vintage Crystal Oven

Bernd Neubig BNeubig at t-online.de
Sat Apr 11 06:37:22 EDT 2015

I have a few similar thermostats, which were sold in the 70ies by KVG Germany under their P/N XT-1. The manufacturer was Northern Engineering.
The oven comprises an Octal type tube socket, in the interior there are two sockets for two "HC-6/U" style crystals. The temperature control is by a bi-metal switch in series with the heater coil, which is a resistor wire wound around the cylindrical body. I had measured the temperature stability those days, the test report is still in the box ;) The thermal hysteresis of the bi-metal switch causes a periodic temperature change within 0.3 K, which is not too bad.

Best regards

Bernd  DK1AG

-----Urspr√ľngliche Nachricht-----
Von: time-nuts [mailto:time-nuts-bounces at febo.com] Im Auftrag von Dave M
Gesendet: Samstag, 11. April 2015 00:48
An: Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] Vintage Crystal Oven

Thanks George,
I used to work in a Motorola 2-way shop.  The only heated ovens that Motorola used were the 6.3V thermostatically controlled ovens.  Those were used in the old tube-style units.  When they went solid-state, they used TXCOs in both base and mobile units.
However, I'll check them out.  Never know, there might be something useful there.

Dave M

George Dubovsky wrote:
> I'm not sure I remember the exact one you are describing, but in the 
> last month or so, there was a fellow selling crystal ovens on QTH.com. 
> I think they were from land-mobile service, like Motorola base 
> stations or some such. That's another place to search.
> 73,
> geo - n4ua
> On Fri, Apr 10, 2015 at 12:37 PM, Dave M <dgminala at mediacombb.net>
> wrote:
>> Years ago, (70s maybe) I came across an empty crystal oven. I know I 
>> have it in one of the storage containers of old stuff in my garage, 
>> but I can't find it.  It was a proportional oven, but was otherwise 
>> an empty shell, so you could put your own circuitry inside 
>> (oscillator, voltage reference, etc.). Several small wires came out 
>> of it for power, temperature adjustment, e.g. Physical size was in 
>> the neighborhood of 1.5x1.5x3 inches.
>> As I remember, it was manufactured by one of the major crystal 
>> manufacturers of the day (e.g., Knight, Bliley, etc.)
>> Does anyone remember these ovens?  I'd surely like to get my hands on 
>> a couple or three to play with.  I search the net & Ebay occasionally 
>> for them, but so far, no hits.
>> Dave M

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