Any ideas on this one???

[Dagwood]

Hi all,

I've searched the web for over an hour and cannot find any details on this valve😕

Print reads,

STC
290
4013
AUG - 60

Any ideas???

Thanks

 

[HollowState]

It isn't a tube. It's a crystal and it looks like it might be bad. the connection looks broken off. Maybe just the picture?

 

[Dagwood]

Thanks for that any more info ???

Seems tobe intact to me, have attached another pic




Thanks

 

[HollowState]

Ok, now it looks better. Probably quartz. No telling what the frequency is by those numbers though. By the thickness of it I'd guess it was fairly low. Maybe 100K or so. (?) You'd have to hook it up with something like a one transistor Pierce oscillator and measure the frequency.

 

[Dagwood]

Thanks Hollowstate

Will put that one away for a rainy day.

Thanks again.

 

[Wavebourn]

Most probably it is not quartz, it is a salt crystal resonator, that's why it is in sealed envelope. But may be it is a quartz. 290 KHz?

 

[rotaspec]

And you have to ask yourself how did the guy get his hand in there to write the "699" on the mica? 😀

Gary

 

[tomchr]

One thing I've come to appreciate about tubes is that you can tell the pinout by looking through the glass at the internal connections...

I'd run an impedance sweep. Ground one side of the XTAL and hook up the other side through a resistor (10 kOhm would be my starting point) to a function generator. Then measure the voltage across the XTAL as you sweep the frequency. You should hit minimum voltage at the series resonance and maximum voltage at the parallel resonance.

~Tom