[ARC5] Odd Crystal Oven

[Bruce Long]

For what it is worth it is standard practice to include the oscillatory circuitry in the heated portion of a ovenized oscillator. For some time roughly in the fifties and early 60's it was apparently adequate to heat only the crystal and then often the heater control mechanism was a thermostat not a proportional oven controller.  In general the interior oven temperature will be set as much as 10-15 degrees C above the maximum expected "ambient" temperature.   Ambient is in quotes because the temperature inside an equipment enclosure will be significantly about the ambient temperature outside the equipment enclosure and the oven temp needs to be significantly above the inside-of-the-enclosure temperature.
So yes they do run hot.


      From: Robert Eleazer <releazer at earthlink.net>
 To: arc5 at mailman.qth.net 
 Sent: Tuesday, June 7, 2016 4:31 PM
 Subject: [ARC5] Odd Crystal Oven
   
 I was working on my SG-297 signal generator yesterday, in preparation for using it to test a PRC-77 I bought.  I found the calibrator was not working and discovered something I think unusual.   The 1 MHZ oscillator module does not only use a crystal oven, the whole oscillator is in the oven.  And that sucker gets hot, too!  I wonder if baking a 2N706 transistor and its related components like that is a good idea?  Anyway, I have never seen this done before. I ordered a 1 MHZ oscillator module and I'm going to try to replace the original with that.
WayneWB5WSV        
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