[time-nuts] Frequency divider design critique request

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Jul 12 19:03:15 EDT 2008

Bruce Griffiths wrote:
>> I was only thinking that maybe there ought to be a buffer from the input
>> to the rectifier, or else higher frequency energy will escape out 
>> towards the
>> source. At least some isolation should be there.
If one uses a common base stage to drive the diode frequency doubler 
transformer primary, then the high impedance drive minimises the effect 
of diode thresholds and mismatches, however it is necessary to connect a 
resistor in parallel with the shunt inductor in the diode doubler to 
provide a well defined relatively low load impedance at the 10MHz output 
Reverse isolation of 40dB or so is possible when using a common base 
stage at  frequencies of around 10MHz or so.


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