> I have a small question regarding my YC156 Amp.
> I'am using a roller inductor in my tank circuit.
> The roller will be driven by a gearmotor.
> Is it "deadly" to mount the gearmotor, say 4-5 inch
> away from the roller on a extended shaft ? Or do I
> absolutely need to mount the gearmotor on the back of
> the amp, outside the cabinet, so that the Q of the coil
> won't be influenced by it.
In air wound inductors flux can move away from a "shorted turn"
caused by surrounding metal with only a minor change in Q.
Tank circuits operate with such low loaded Q that what surrounds
the coil make little difference in efficiency, as long as it is a half
coil diameter or so away.
Loading coils for heavily loaded mobile antennas are a different
story. Any reduction in Q caused by stray capacitance shunting
the coil or eddy currents will kill a mobile coil's performance.
73, Tom W8JI
w8ji@contesting.com
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