Tuning When You Do Not Know The Last Operating Frequency; Tuning With A Known Direction Of Frequency Movement - MFJ Box Fan -1780 Instruction Manual

MFJ-1780 Box Fan    Loop Antenna
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
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
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).
YOUR ANTENNA!!!!
YOUR ANTENNA
11
Instruction Manual