Hi Doug,
One normally doesn't run a varactor down to 0 volts (as Han's
chart showed), but at minimum 1 volts. I tested two brands of
rectifier--1N4003 and 1N4007.? The 4003 at 1V was 10.6 pF and at
12V was 5.2 pF. The 4007 at 1V was 7.8 pF and at 12V was 3.8 pF,
so quite a difference, relatively speaking. I don't have a MV209
to test but the specs say it's a nominal 29 pF varactor at 3
volts; the data shows? a graph with about 44 pF extrapolated at
1V. So comparing the 1Nxxx to MV209 show quite different total
capacitances which of course would also give a smaller tuning
range for the 1Nxxx vs. for the MV209.
73,
Steve AA7U
On 4/30/2025 4:10 PM, Doug Hendricks
via groups.io wrote:
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What is your experience with using the 1N4004 diode as a
varactor in tuning circuits?? How does it compare to the MV209?
In the same circuit, what is the comparison between the 2 diodes
in tuning range?
