[Elecraft] Motor for Cap in Mag Loop

[Matthew Cook]

John,

Firstly build your loop with your chosen capacitor and see how much Q you
can achieve.  From there you can work out by how much (or how little!) you
have to rotate the shaft per kHz of change.   This will then dictate how
you computer control your loop.

Unfortunately you need to start at the other end of the project first and
work backwards to find the right motor and gearbox.  Transmitting loops
with high Q can be fiddly to tune and then hold in tune, especially when
they are only 3kHz wide.

73

Matthew
VK5ZM


On 28 October 2016 at 12:36, johnpierce <ja-pierce at verizon.net> wrote:

> I have seen general definitions about motors for driving a capacitor in Mag
> Loop.   But I have not seen a recommendation of a specific type to look for
> on Amazon or Ebay.  For starters I am looking for a 12vdc reversible motor.
> I would like to start with a simple push button system for tuning.  Maybe I
> will consider a stepper later.  I think that would need some computer
> control.  I am also wondering what RPM to consider for use on the lowest
> frequency (40mtrs).  The capacitor I am expecting to use would not have a
> stop and could travel a full 360 degrees.
>
>
>
> John
>
> Ad2F
>
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