"Reg Edwards" wrote in message
...


The trouble with as many as 8 single-throw, high-current, high-voltage
switches in a tuner, is the stray inter-component wiring and inductance
and
capacitance they introduce.

Even with a minimum number of, or no switches, it requires TWO independent
tuners, in separate boxes with separate coaxial connectors, to cover the
range 1.8 to 30 Mhz with reasonable power efficiency.

You need practical experience by building one or two to see how they
perform. Try again and then come back!


Would a solution based on two, contra-rotatinng "roller coasters" not be
better? This would enable a true balanced ATU to be made, offering a wide
matching impedance, and, with motorised capacitor, avoiding switching all
together?

Making a suitable capacitor is straight forward. The rollor coaster former
will turn up on a lathe nicely (I've made a similar former from PTFE in the
past). The rest of the mechanics are easy enough.

--
Brian Reay
www.g8osn.org.uk
www.amateurradiotraining.org.uk
FP#898