[time-nuts] EFC Input pin impedance for the HP 10544A and10811-6011

[Bruce Griffiths]

Mike Feher wrote:
> While it is difficult to read the resistor values on that schematic (and as
> Bruce points out not really relevant as the diodes are reverse biased), it
> appears that since the varicap is referenced to ground, the 10544A's EFC is
> always positive. The 10811A goes from -5 to + 5 as the cathode end of the
> diode is referenced to +6.4 volts. All this time I had thought they were
> fairly interchangeable. - Mike 
>
>  
>  
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>  
>   
Mike

Get yourself a better GIF viewer and magnify the image (all component
values can then be read), you will find there is an option to connect
the varicap cathode to +6.4V just like the 1081.
The problem only arises if one has the other option.

Bruce