> If you wire the contacts without some thought as to voltage
> differences, and especially if you don't short a portion of the unused
> coil, you can make a large switch fail in a very small PA.
Designing a successful continuous coverage (1.8-30mhz) Pi-L
tank circuit is no small feat.
Henry faced a problem with the 3-K Ultra and 8-K Ultra.
The Pi coil required 30 uh of inductance. Henry uses no
band switches, only solenoids to switch fixed caps for each
band. The tank is tuned by motorized roller coils (both Pi and L)
that are ganged together in such a way that any position of
the Pi coil results in an optimum setting for the L coil at any
given frequency of operation.
On 40 meters and above, another solenoid is used to short out
1/2 of the Pi coil, reducing it to a total of 15uh. This was easy to do
because the coil is stationary, and the roller moves about inside
the coil.
I have no doubt that fireworks would result sans this solenoid.
(((73)))
Phil, K5PC
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