[time-nuts] HP10811 problem - wrong frequency

SAIDJACK at aol.com SAIDJACK at aol.com
Sun Jan 13 15:48:01 EST 2008

In a message dated 1/13/2008 10:58:10 Pacific Standard Time,  
BNeubig at t-online.de writes:

>The  oscillator has obviously jumped to the so-called B-mode of the 
>SC-cut  crystal. The C-Mode operation (3rd overtone) is enforced by a 
>circuit  consisting of two inductors and two capacitors which is 
Hi Philip, Bernd,
happy new year!
I agree with Bernd completely, there are two tank circuits, one that keeps  
the crystal at third overtone (L2 with DC-blocker C5), and one that prevents  
operation at 10.75MHz (C6 and L3)
C6 with L3 compose the 10.75MHz tank which is supposed to prevent B Mode  
operation by loading down the crystal at that frequency.
One of those two components is very likely damaged. Try replacing them with  
high-temp, high accuracy components. Try to get components with as high a Q as 
If L2 is broken, then the circuit would oscillate at about 3.5MHz.

**************Start the year off right.  Easy ways to stay in shape.     

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