Author: AA7OL Niko
Takahashi - aa7ol@hotmail.com.MODIFICATION.NET
Icom AH-4 and AH-3 ( automatic antenna tuner ) connection to any
radio
Both AH-3 and AH-4 are similar 
Here is a redesign of
connection digram of the ICOM IC-AH3 and IC-AH4 by
5B4AEZ.
There is four wire control cable coming out beside coax cable.
Control cable has
White: Start tuning
Green: Tuning in
process
RED: 12 V DC input
Black: GND
Tuning Process
- Put about 10 watts of power into tuner. ( CW )
- After about 0.5 second, press start switch for a moment. ( use
momentary contact switch )
- LED start blinking , which indicate tuning is in
process.
- After about 3 seconds or so, LED shut off, and tuning is
completed,
If tuning is successful SWR should be less than 1.2
Some radio start to reduce the power when SWR is high, this tuner
takes at least 10 watts of power for tuner to work properly. Most of
the 100 watts radio should not have any problem, since they still
put out 10 watts or so, even with high SWR.
But, it does not work with some QRP radio ( 5 watts or less ).
Adjust power level, if necessary.
You may extend control cable to 100 feet , it still work fine,
you can put this tuner on top of tower.
Let me know , how it worked
aa7ol@hotmail.com.MODIFICATION.NET
| 
