voltage. It should dip to just about 0.0 volts. You MUST use a 50 ohm load to properly do the alignment. If the
load is not resonant, you may get more than 0.0 volts on the REV test point. Anything less than 0.2 volts will
provide satisfactory results.
Then, apply 5 to 10 watts to the input. Adjust R23 for 2.5 (2.3 to 2.5 is Ok) volts on test point FWD.
Move the dummy load to the input and apply 5 to 10 watts to the output. Adjust R24 for 2.5 volts on test point
REV. Be sure to not go over 2.5 volts on either test point.
If you don’t get 5 watts out of your radio, use 2 to 3 watts and adjust for 1.5 volts for both. That's it,
the tuner is now ready to be placed on the air.
Operation Notes:
In general, the tuner operation is straight forward (you push the tune button and it
finds a match) and works as described in the introduction section of this manual.
The software for the QRP version was modified slightly from the original AT-11 to help reduce power
consumption. When the tuner is in the semi mode, the processor will go to sleep after it finds a tune. This
reduces power consumption by about 20 mA once a match is found. Note that while the processor is asleep, the
LEDs (if used) will also be disabled. The processor can be woke up by pressing the tune button once while no
RF is present. It can also be forced to go to sleep by simultaneously pressing both down fine tune buttons (if
used).
When the tuner is in the auto mode, it does not go to sleep, it stays awake to monitor for an SWR of
above 3:1. Again, it can be forced to go to sleep by simultaneously pressing both down fine tune buttons (if
used) and be woke up by pressing the tune button once while no RF is present.
Although specified for 10 watts, the actual maximum operating power can be as high as 30 watts (at
50% duty cycle). The relays are rated for over 30 and the toroids will handle about 50, but the RF input
power should never exceed 30 watts..
If the LEDs are installed, they will indicate SWR whenever there is more than .1 watts of forward
power. If you press the tune button and there is less than .1 watts of forward power, it will not go to the tune
algorithm and all LEDs will flash once.
You can use SSB to provide the power for tuning. Just press your mic and say something (like
“Ahhhhhh”) until the unit stops tuning (somewhere between .1 and 3 seconds). If the tuner has a hard time
finding a match or doesn't find 1.5, try using a CW or AM carrier.
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