[Lowfer] RX Loop Tuning

Thu, 1 May 2003 11:19:14 -0400

Bill,
Using cat 5 wire to bring in the antenna provides one with a certain measure
of noise immunity from feedline pick up.
It also gives one  3 addition pairs of wire to things like motor control.

The isolation between the motor control and antenna leads is superb.  There
has has never been a time whe I can hear the brush noise from the motor
turning the cap.  Actually I wish I could hear it a little it would help in
the tuning of the ant at imes.

The other pairs are great for headphones, preamp power, etc.

Paul C
W1VLF

----- Original Message ----- 
From: "Bill Ashlock" <[email protected]>
To: <[email protected]>
Sent: Thursday, May 01, 2003 10:43 AM
Subject: [Lowfer] RX Loop Tuning

> Jay/others,
>
> I've been experimenting with my motorized trimmer cap over the last few
days
> and it seems to be working fairly well. In review, this is a 2"x4" box
> containing a small Jameco gearmotor and 3/4" square compression mica that
is
> located below the loop. (The gearmotor voltage is provided via the coax
> leadin).
>
> Last night I changed the control box at the receiver so that the receiver
is
> connected at all times - not disconnected when either UP or DOWN buttons
are
> pressed. Used a couple of shockty diodes and 100 ohms of series resistance
> to protect the receiver's input (and ears). This appears to work fine.
>
> Pictures and schematic to follow after a more thorough check. Next idea is
> to replace the push buttons with a 500 ohm pot connected to the + and -
> voltage sources. This will allow a slow motor rate for fine tuning and a
> fast rate for large frequency changes - IE: from 137k to 185k.
>
> Bill
>
>
>
>
>
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