I have just about collected all the parts to build my next project and I
will soon be faced with the decision of how to switch bands with the final
tank circuit. I see three options:
1. Use the EF Johnson 222-101 variable inductor that I've been saving for
the last few years. I used a roller in my last large amp, chiefly do to the
fact that I had it and it saved all the trouble of fiddling with taps and
such.
2. Use a big strap wound inductor and large ceramic switch. I have the coil,
but will need to locate a switch.
3. Use the aforementioned coil but switch it with relays, which I would
still need to procure. This offers the advantage of being able to remote
control the band change at some point in the future.
I am hoping some of the more experienced builders can offer some opinions
and suggestions regarding the technical merits or shortcomings of these
three choices. Is one method or the other more subject to random parasitic
oscillations? Is tank circuit heating more of an issue with one or the
others? What other considerations do I need to ponder in this regard?
I have looked through most of the archives and could find no previous
discussion on Rollers verses Switches so any and all thoughts and ideas are
welcome.
Thanks & 73,
Theo - K4MO
www.qsl.net/k4mo
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