"Peter Parker" wrote in message
...

"S C" wrote in message ...
I would be grateful if anyone could suggest or provide me with a circuit
diagram for a Homebrew ATU with SWR meter or circuit diagrans for these
seperately.

The simplest ATU is an L-match. Comprises a coil and a capacitor.
Explain
that it is useful for matching high-impedence end fed wires approx half
wavelength long to 50 ohm and you should pass.


Yes - have a look at my version
http://www.hanssummers.com/radio/atu/atu.htm. I included a 50-ohm 10 Watt
dummy load and forward/reverse power meter. It doesn't read SWR directly, if
you really want to know the SWR then you measure the forward power and the
reverse (reflected) power and put them in the SWR formula.

In practice, 99% of the time you don't care about SWR, you just tune for
minimum reflected power. Operation is very easy - when switched to reflected
power, tune the capacitor to get minimum indicated reflected power. Then try
different L settings by switching the coil tap, and see which setting allows
the reflected power minimum to be deepest. I have a 1W full-scale-deflection
setting for the fine tuning. Then switch to forward power and away you go.

No need to know the actual SWR in practice; the only time I have bothered to
calculate it is when I want to tell people how close to 1:1 I can tune my
various incarnations of longwire antennas. Random length, not cut to any
particular band. Including the bent indoor attic "short"wire I had my first
QSO's on. So far I am very content with my ATU, I have been QRV on 80, 40
and 30m and always found it works well.

73 Hans G0UPL
http://www.HansSummers.com