Tim Shoppa wrote:
On Nov 13, 12:26 pm, Ross Tucker wrote:
I am almost ready to begin fabrication of a new transmitter that I
have been working on for a long time now. However, one detail is still
eluding me- I would like to use a single rotary switch to select taps
on two different coils. In-line ganged switching would be inconvenient
for my layout. Is it possible to homebrew a mechanical linkage to turn
two switches? I have a front panel and metal deck (vacuum tube
construction style), so I could mount gears and cams and stuff, and my
layout does have a good clear space between the coils, so there is
room. My problem is that I have never read anything about doing this
and don't know where to begin looking for parts, etc. Again, I have
two coils with four taps each for 40, 20, 15, 10m.

Thank you very much for any thoughts on this matter.

Look at the parts assortments that Robotics Hobbyists buy, from e.g.
Jameco and other places. http://www.jameco.com/ search for "robotics".

Berg and Small Parts Inc sell gears and sprockets and roller chain in
small quantities but they are not cheap. Jameco is cheap.

Sprockets and roller chain or belts are surprisingly effective if not
all your shafts are in-line.

For low-level switching, using relays controlled by DC voltage busses
is great. Surplus small relays are available in vast quantities at
very cheap prices. For non-mechanical switching, diodes can be biased
on and off by DC voltages to act as switches. But once you get to
higher level switching (e.g. transmitter tanks) the cheap relays may
not take the currents or voltages involved. Still, there was an
article in QST a few months ago that used small relays to change the
electrical length of a wire antenna, I was a little surprised at how
do-able it looked.

Tim N3QE
Another good source for gears and sprockets is www.smallparts.com They
have lots of couplers, tubing, tools, etc as well. Great source for
robot prototyping too.