[Lowfer] remote auto tuning

Tue, 22 Apr 2003 17:44:28 +0100

In message
<[email protected]>, Eric
Smith <[email protected]> writes
>For you design engineers out there (Lyle? :) --
>
>Several weeks ago (when first getting interested in LF), I read about
>WWVB.  That antenna is tuned automagically.  From their web page:
>
>----
>A computer is used to automatically tune the antennas during icy and/or
>windy conditions. This automatic tuning provides a dynamic match between
>the transmitter and the antenna system. The
>                    computer looks for a phase difference between voltage
>and current at the transmitter. If one is detected, an error signal is
>sent to a 3-phase motor in the helix house that rotates the rotor inside
>                    the variometer. This retunes the antenna and restores
>the match between the antenna and transmitter.
>----
>
>How tough would it be to design a circuit to do this?  I think this is
>pretty cool.  You guys already have means for remote tuning...what about
>automation?
>
>Ok, it may be more trouble than it is worth.  But how hard would it be
>to do?  Would the resulting circuit be very compicated, or could it be
>done with just a few components?
>
>And I'm talking about a circuit that could drive a SMALL motor for
>LowFER-type use, not the 3-phase motor driving the variometer at WWVB!
>
>What do you think?  Food for thought?

I have an ARRL publication dealing with mobile operations in the valve
(tube) days. It gives the circuit for an auto-tuner which uses only 2 or
3 triode valves.

 Mike
-- 
M.J.Powell