MFJ
Super Hi-Q Loop
Antenna Instruction Manual
7
INDOOR CONTROL BOX INSTALLATION
WARNING! Do not install any devices between the control box and the loop antenna! If
anything causes a low DC resistance or short between the center conductor of the
coax and ground the control box or power supply will be damaged.
The control unit of the MFJ "Super Hi-Q Loop" can be located at any position that allows easy access
to the controls of the unit and the transceiver. The coax lines should be good quality 50 ohm lines and
should be kept reasonably short to reduce losses. If you use quality low-loss cable, the exact lengths
used are unimportant and will not effect the operation or SWR of the system. However, if you use
lossy cable adjustment of the control head may be necessary.
If you are using a lossy cable between your antenna and controller and have problem tuning, the easiest
way to correct the problem is to get better quality cable. If changing the cable is impractical,
adjustment of R10 to the minimum may correct the problem. If you still get a needle dip and the motor
does not stop, adjust R10 to the middle setting and try shorting R11.
The power supply used with this unit must not be connected to any other devices while connected to
the loop control box.
CAUTION: The power supply of this unit must not be grounded! If either the positive or
negative leads are grounded the control unit will be damaged! Use only the MFJ-
1312B, MFJ-1315X or equiv. supplied with this unit!
Figure 6
