MFJ-1780
Box Fan
Loop Antenna Instruction Manual
12
1 -
Adjust the transmitter to the new frequency and transmit a steady,
unmodulated carrier
(1-15w is
ideal).
2
- Press the appropriate
Fast Tune
button in and observe the SWR or the reflected power meter. The
LED should light while searching for the new tuning position at this frequency.
3 -
After the reflected power goes through a dip release the
Fast Tune
button.
4 -
Press or tap the appropriate
Fine Tune
button while carefully watching the SWR or the wattmeter's
reflected power for the lowest reading. BE ALERT. This dip is very sharp.
After the lowest SWR point is reached you are ready to begin operating.
TROUBLE SHOOTING
The following suggests the most likely causes of abnormalities in operation:
If the LED's dim suddenly any time during operation.
Check that the coax is connected properly.
Check for a short from the antenna coax center conductor to ground.
Check for a short from the DC power supply to chassis ground.
If you push a Tune button and the Tune LED stays on for more than 40 seconds.
Check for moisture in the feedline or antenna.
If you press a Tune button and an LED does not light.
Check to see if you are at the end of the tuning range (press the other tune button, LED will light).
Make sure one of the Fast tune buttons are not latched.
Check for an open in the coax between the controller and the antenna.
If you tune throughout the entire range of the antenna and get no SWR dip.
Check the mounting of the antenna (too close to a building, or other improper mounting, etc.).
Check that you are transmitting within the range of this antenna (14.0MHz - 30MHz).
If the meter did not dip while tuning
Check to make sure that your tuning signal is an
unmodulated carrier
If the meter dips, but the slow buttons will not tune the antenna.
The slow speed buttons may be pulsing too slow to overcome the backlash spring tension. Remove the
cover of the controller box and find R1 While holding one of the slow tune buttons adjust R1 for a
faster pulse (LED blinks Brighter). Test for tuning across the bands. Replace the cover.
If the slow tune buttons are too fast to tune properly.
