Re: Xtal filter bandwidth


William Kimber
 

Thanks Nick,

Didn't expect I would have been first to think of idea.

Cheers,
Will


On 15/09/15 10:41, Nick Kennedy kennnick@... [PHSNA] wrote:
 
Jim Kortge K8IQY did that pretty effectively in his famous 2N2/40 transceiver.  You can check it out here.  Not sure about the termination effects.



73--

Nick, WA5BDU


On Mon, Sep 14, 2015 at 5:36 PM, Will zl1tao@... [PHSNA] <PHSNA@...> wrote:
 


Would it be practical to use varicap diodes to vary bandwidth of xtal
filters? Instead of using fixed value caps it is obviously possible to
replace or use in parallel with fixed capacitor between xtals to ground.

However would the low Q of varicaps and or the resistor used to feed the
DC to them upset the Q too much. Also would it effect the termination
impedances so that the matching was not matched.

Cheers,
Will



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