On 01/17/14 16:00, Michael Black wrote:
On Fri, 17 Jan 2014, Zach Metzinger wrote:

You could also dispense with the mechanical capacitor completely and
use a varactor diode tuned by a voltage. I've even seen some designs
use a regular LED reverse-biased in a pinch.

But, there will always be a time when you can't come up with an
alternative. High voltage variables for transmitting loops, or output
circuitry in a transmitter. Varactors won't work in that situation.

And that's when you'll need to make variable capacitors. At the best of
time those weren't readily available (likely requiring a special order)
and were relatively expensive. Now, they are outright expensive, if you
can find them.

Michael VE2BVW

Michael-

Excellent point, and I sit corrected. I need to read more closely next time!

DE N0ZGO