help identify this part please

[Geo]

im getting around to opening some older electronics and the first thing i come across is something ive never seen before. its a unit called "crystal oven".it HP. its military. the crystal is what im interested in. its operating range is around 1265 degrees F or 680 degrees C. im hoping some of our electronics guys know what it is and maybe if its still a serviceable part or maybe a collectors item.

 

[grance]

Old school crystal oscillator would be my guess. Agine Geo just guessing

Found something

http://www.lintechcomponents.com/product/001133612/051106043/28480

 

[qst42know]

That reads 68.5c and 69.5c.

 

[element47.5]

It's a heater inside a can to keep a quartz crystal at a constant temperature. The crystal is used to control the oscillating frequency of an oscillator which the mfr did not want to drift as the surrounding components and environment heated up. Thus, the crystal is heated up slightly when power is applied and there is provision for regulating the temperature inside the can (by turning the heater off, if needed) where the crystal resided. They are occasionally still used, but far more often, frequency shift is controlled via PLL = phase locked loop. Much more accurate.

 

[g_axelsson]

Dohhh... three replies while I was writing my reply. :mrgreen:

Crystal ovens is used to create very precise frequency standards.

When you build an oscillator you have a crystal as a critical component that decides which frequency the oscillator runs at. No oscillator can be more precise (generally speaking) than the crystal. But the crystal changes physical resonance properties as it expands and contracts when the temperature changes and so the frequency changes. Often no more than ppm per degree but enough to be a problem. But if you run it at a fix temperature then it will not change frequency and you got a very precise oscillator.
As it is easier to heat something up and keep a constant temperature than to cool it down, temperature controlled crystal ovens is usually found in high precision oscillators.

My guess is that your crystal comes from an old HP frequency counter. It could also come from some old radio equipment, but the frequency is a bit low for that. I don't know if it has any collectors value.

685 C working temperature sounds unrealistic, isn't there a decimal point there? 68.5 degrees C feels a lot more reasonable.

/Göran

 

[resabed01]

I have a old TSI frequency counter here that has the 1Mhz crystal oven in it. Back in it's day it was high end stuff, nixie tubes and all. Now I keep it for collector value even though it is not very versatile by today's standards... still works.

 

[Geo]

yes, it is 68.5, i didnt see the point for the line till i looked at it again. thank you guys for the info. it did come from an old Oscilloscope type piece of equipment. it may have been a radar screen or test fixture. the units are all aluminum and stainless steel and have double rows of white porcelain bridge type connectors with resistors and capacitors and transistors between them 1 leg on each side. the slots that are empty have a thick solder like metal that test strong for silver.any way, ill keep digging and hoping i dont tear into something thats radioactive. :shock: