Here is a link to the original 1996 QST article on homebrewing a tuner
called the AT-11. It is now made by LDG Electronics. It uses relays to
switch inductive and capacitive elements in an L-network tuner
configuration.

http://www.3764.net/qst/1996-1999/au...tuner_at11.pdf

The article presents the complete schematic and theory of operation, but
there is no microprocessor source code included. The author does say that
you can but a programmed chip from him, but I don't know if that's still
available. Maybe someone in this group can suggest where to get source code
or a hex file of the object code.


Joe
W3JDR



"Paul Keinanen" wrote in message
...
On Sat, 19 Feb 2005 21:43:57 -0800, "Andrey"
wrote:

How do I design an automatic antenna tuner with no moving parts?

This is a good question.

How to do it - without relays, motor driven capacitors and inductor
cotacts?

1.) Since you did not specify the power level, use varactor diodes and
inductors on a suitable core material and vary the core permeability
with an external magnet field, controlled by a variable DC-current.

2.) Alternatively, get rid of the antenna tuner by using resonant and
matched broadband antennas.

Paul OH3LWR