Eric KE6US
¿ªÔÆÌåÓýI think the curves on Diz's page are in the best
format for varactor capacitance. We normally consider the
voltage input linearly. If I'm graphing one, I automatically
mark off the V (x) axis in evenly spaced volt increments. But
I'm normally looking for something different on the output.
Marking the C (y) axis linearly makes no sense. We are rarely
looking at the linear response of a varactor because we aren't
really concerned with capacitance. We're normally concerned with
the resulting resonant frequency response in a tuned circuit.
Log/linear can help us with that. Most of the time, I want a frequency readout to
be linear. A varactor capacitance with a non-linear response to
voltage is going to give me that. On Diz's graphs, I see a
linear voltage input. If I see a fairly straight curve for C,
I'm probably going to get a fairly linear frequency response. So
log/linear makes sense. If he used linear/linear, you would see
a deceptively "hooked" curve that truly shows how C responds,
but it wouldn't be as useful for predicting frequency response.
Log/linear provides more insight that you can use. Some of the newer hams may not have noticed the shape of the plates on larger "tuning" capacitors. They weren't symmetrical. They were very oddly shaped to make the dial calibration more linear. There. Marketing guys owe me one. BTW, I used to follow your website pretty closely
in the Rock Mite days. Fun stuff. Eric KE6US On 12/20/2019 6:54 AM, Chuck Carpenter
wrote:
Looking closer at the chart posted previously?from Diz's?diodes page |