[R-390] R-390A calibrator oscillator

[Charles P. Steinmetz]

John wrote:

>the 100KC calibrator has a "raspy" sound rather than a more "pure" 
>sinusoidal sound.
>
>First, shouldn't the calibrator sound like a sine wave?  Nice clean sound?

Yes.  Does the radio give a nice clean tone on a CW input (say, the 
carrier of WWV) beat with the BFO, or is that raspy, too?

"Raspy" sound could be caused by AM, FM, or spurs on the cal signal, 
or by AM, FM, or spurs on any of the local oscillators (including the 
BFO).  If only the cal signal sounds raspy, then the modulation is 
more likely on the cal signal itself.

>I have attached a portion of the scope trace at pin 7 of the V205

The reflector strips attachments, as most reflectors do, so the pic 
didn't make it.  Can you put it on the web and post a link?  You will 
probably find that the voltage at pin 7 changes if you change the 
tube.  Is the voltage at pin 8 correct (0.36 V)?  Scope traces of pin 
8 and pin 1 would also be helpful.

Best regards,

Charles