On Tue, 11 Jul 2017, Gareth's Downstairs Computer wrote:

Taking my cue from bandswitching in other designs,
and being motivated by the catacomb in the HRO
NC100X, I wonder if any have encountered bandswitching
by cam driven microswitches?

I presume that the contacts in microswitches must be
similar to those in small relays, and, being mechanical,
would not be subject to electrical failure.

Remember turret tuners? The coil came to the place where it was needed,
rather than long wires from a switch to the coils.

But, there was a time when diodes were seen as the way to go, using DC
voltage to turn on the diodes. So you weren't stuck with a big switch
running through things, or having to keep wires nice and short. I'm not
sure if this has gone far in more recent times, I suspect other things
have happened.

Get some small relays and use them. Though I don't know about small
relays that don't contribute to inductance.

In this modern age, redundancy gets around switches. Instead of switching
coils, use a transistor per band for each stage you need, and then
switching bands means switching which oscillator gets DC and which
amplifier gets DC, and maybe switching the signal path. But that's easier
than switching coils in and out of a circuit.

Make things as wideband as possible, then add filters as needed, switching
50ohm impedance rather than high impedance of an inductor.

One guy used to write about building shortwave receivers in CQ. He built
endless receivers, but most of them were single band. That has
advantages. In these days of DDS synthesizers, one could just build
single band receivers or transceivers, and then have one DDS synthesizer
to control them all.

Michael