MFJ-1780
Box Fan
Loop Antenna Instruction Manual
11
After you have tested the loop as described in the TESTING AND OPERATION section you are ready
to learn the
short-cuts
necessary for easy, day to day, use of this antenna. The following section will
help you learn these
short-cuts,
as well as locate any problems that may occur with your new antenna
system.
There are two basic methods that you can use to tune the antenna during daily operation. One method
requires you to know whether the new frequency is higher or lower than the last frequency used, the
other method must be used when you can't recall the last frequency where the loop was used.
TUNING WHEN YOU DO NOT KNOW THE LAST OPERATING FREQUENCY
ALWAYS REFER TO THE WARNING SECTION ON PAGE 1 BEFORE OPERATING
YOUR ANTENNA!!!!
If you ever loose track of the last frequency the loop was used on you should follow this procedure:
1 -
Press the
Fast Tune
"UP" button. The frequency "UP" LED should light as the loop moves to the
highest frequency range. After the LED goes out, release the
Fast Tune
"UP" button.
2 -
Select the proper wattmeter range for the power you intend to use in tuning the loop, then switch to
reflected power. Transmit a steady, low power,
unmodulated carrier
on the desired operating
frequency.
3 -
Press the
Fast Tune
"DOWN" button while carefully watching the SWR or the reflected power
meter for a dip, be ready to release the button at that point.
5 -
Press or tap on the required
Fine Tune
button while carefully watching the SWR or the reflected
power meter. This adjustment is very sharp and you may pass the lowest SWR point slightly.
6 -
Tap the other
Fine Tune
button until the reflected power is as low as possible.
-You are now done tuning the loop. Any small changes in frequency can be handled by using the
Fine
Tune
buttons.
TUNING WITH A KNOWN DIRECTION OF FREQUENCY MOVEMENT
ALWAYS REFER TO WARNING SECTION ON PAGE 1 BEFORE OPERATING
YOUR ANTENNA
This method of tuning should be used when you know what direction the antenna needs to move. If the
change is small then only the
Fine Tune
buttons need to be used (go to step 4).
