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Re: 7 MHz Oscillator Ideas

 

Yes, the capacitance change of a varactor per volt decreases as voltage increases. But remember that the capacitance change has more "worth" at low levels. For example, in a tank with only a varactor for the capacitance (not likely, I know), you'd get the same frequency change going from 20 pF to 10 pF as you got from 200 pF to 100 pF.

In cases where that matters, I've often tried to keep that voltage range up. But as the other poster said, it's important that it be regulated.

73-

Nick, WA5BDU

On Tue, Dec 10, 2019 at 2:52 PM Chuck Carpenter <w5usj@...> wrote:
Jerry,

The capacitance beyond 10V changes very little.? The plotted curves by k7qo?in the attached chart show that. The MV209 is similar to the BB910 that I used.

Note too that the curve for the 1N4004 shows very little change beyond about 4-5 V. That curve is typical of junctions from devices like diodes and LEDs and etc. The max C might be more or less at 0V depending on the size of the junction.? But the shape of the curves is about the same.


--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv

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