[time-nuts] Setting Osc Frequencies

[Dr Bruce Griffiths]

Robert Atkinson wrote:
> Hi Bruce,
> It's a while since I looked at the HP circuit and patent, but if I
> recall correctly a lot of the performance relied on the input circuit.
> This used a line receiver with feedback. When I looked there did not
> seem to be an equivalent receiver chip available. I'm aware of the sine
> -square conversion thread that ran a while ago, but guess this needs as
> much attention as the phase comparator.
>
> Robert.
>   
Robert

Attached schematic is for proposed input circuit (one per source).
The ADCMP600 has low power consumption, a well behaved output stage, has 
a built in 2mV hysteresis and has a maximum input frequency of 100MHz.

The input protection and coupling arrangement is equivalent to that of 
the K34-5991A.

An RF transformer coupled input could be used but this would limit the 
lower frequency limit to a few hundred kilohertz or so depending on the 
transformer.
The HP style input circuit has a lower frequency limit of around 10kHz.

Bruce
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