MFJ-1922B Screwdriver Antenna Controller with counter motor control The MFJ-1922B is designed to give up/down control to tune most screwdriver type antennas. This unit is compact and ideal for mobile installation (H 2 ¾’’, W 4’’, D 1½’’). It features a counter to count turns of the motor inside the antenna. The four-digit readout makes tuning easier by enabling you to return your antenna to a desired position. Your antenna must have a sensor installed in it for the readout to work. If your antenna does not already have a sensor installed, contact your antenna manufacturer or MFJ. Antennas that do not have a 4 pin plug. The plug can be cut off. Use the chart below for wire color and its function. INSTALLATION (A) Controller with six wires The MFJ-1922B can be easily connected. For mobile installations, disconnect power at the battery, until installation is complete. Connect power to your MFJ-1922B using the red (+12Vdc) wire and the black (GND) wire. The red (+12) wire should be connected to your vehicle battery (or 12Vdc source) through an inline fuse (not included). Consult your antenna manual or manufacturer for an appropriate fuse value; normally a 5 to 10 Amp slow blow will work. Connect the black (GND) wire to your vehicle (or station) ground. The remaining four wires connect to your screwdriver antenna. Two for motor control, and two for the motor sensor. You will need to splice wires onto each of these four wires, so that they will reach your screwdriver antenna. Use quality insulated wire for these extensions. The motor control wires (green and yellow) should be no smaller than 18 AWG, and the sensor wires (brown and white) should be no smaller than 24 AWG . Take care and follow your antenna manufacturers suggestions about routing these wires for a mobile installation. Avoid routing control wires with the feed line. Make sure a RF choke is placed around the control lines at the antenna. Connect the motor control wires and sensor wires to the antenna. There is no polarity on the brown and white sensor wires. If the motor travels in the wrong direction, switch the polarity of the green and yellow motor control wires. This control unit is designed to operate with a screwdriver antenna that operates on 12 volts. Installation (B) Controllers that have the 4 pin Molex plug. 1. The red wire needs to be fused and connected to the vehicle’s +12 VDC supply. The size of the fuse depends upon the current requirement of the antenna motor. Typically a 5 Amp slow-blow fuse will work. Some installations may require additional wire. Use 16 AWG wire to add additional length. 2. The black wire needs to be connected to the vehicle (station) ground. If the supplied red and black wires are not long enough, Use 16 AWG wire to add additional length. 3. Connect the 4 pin Molex to the antenna. CONTROL CABLE RED MOTOR WIRE BLACK MOTOR WIRE GREEN SENSOR WHITE SENSOR Many antennas operate on only 3 or 4 volts, a Dropping Resistor is used inline with the motor control line to bring the voltage down. Consult your antenna manual or manufacturer for the operating voltage. See the section Dropping Resistor for more details. WARNING: The MFJ-1922B is designed for screwdriver antennas that operate on 12 volts. Many antennas operate on only 3 or 4 volts, a Dropping Resistor is used inline with the motor control line to bring the voltage down. Consult your antenna manual or manufacturer for the operating voltage. A mismatched voltage could severely harm your antenna. See the section Dropping Resistor for details. CALIBRATION AND OPERATION The MFJ-1922B will need to be calibrated to your antenna. First, turn ON the power to the MFJ-1922B and press the motor control rocker switch DOWN until your antenna is fully collapsed. Then switch OFF the power to the MFJ-1922B. Next, press DOWN on the motor control switch WHILE switching ON the power to the MFJ-1922B. The display will then read zero. The up/down switch may now be used to tune your antenna to resonance on the desired operating frequency. Setup Menu Flow Hold Menu button + Power On Trip Current (C) Relay Delay (d) Set UP Normal Operation After entering setup, the setting and the value are displayed. Pressing Up or Down changes the value. . After the end is reached the last value is saved and the controller continues with normal operation. Trip Current This is shown in the menu with a “C” in the left-most digit. The other 3 digits will display the currently selected value. The trip current value is used to determine when the motor has stalled and immediately shuts the motor off. This feature protects the motor from damage if the antenna becomes stalled. The current is displayed as Cxxx, which translates into x.xx amps. The default setting is C075 or 0.75 amps. This is also the setting for use with the Ameritron SDA-100 Screwdriver Antenna. Relay Delay This setting controls the amount of time the relays are reversed when the motor is stopped. When the motor is stopped, the relay that was moving the motor is deactivated and the opposite relay is activated for the duration set in the menu. The default setting is 20ms. The values range from 0ms – 200ms. UP This determines which button will move the antenna up. This can also be used to move the antenna correctly if the motor terminals are reversed. When UP is on the display, press the corresponding button (Up or Down), which moves the antenna up. This is then saved to memory. Pressing any other key will not make any changes and simply exit setup. Since this is the last setting in the setup menu. The controller will proceed with normal operation. Consult your transceiver/antenna manual or manufacturer for more operating and tuning procedures. Typically an SWR of 1.5 or less is acceptable. If the counter does not read zero when the antenna is fully collapsed, the counter will need to be recalibrated as described above. Recalibration should be done periodically due to vibrations in a mobile environment. The counter on the MFJ-1922B is an aid to help you quickly tune your antenna. Fine-tuning will be necessary. Use the counter to bring your antenna back to a certain portion of a band. DROPPING RESISTOR The MFJ-1922B is designed to work with screwdriver antennas that operate with 12 Vdc. Many antennas operate on only 3 or 4 volts, a Dropping Resistor is used inline with the motor control line to bring the voltage down. Consult your antenna manual or manufacturer for the operating voltage of your antenna. If a dropping resistor is necessary, a good value to try is 5 Ω/10 Watts. This resistor will need to be placed inline on one of the motor control lines anywhere in between the MFJ-1922B and the antenna. If you are not sure whether or not this resistor is necessary for your antenna, try it and inspect the torque and speed of the motor. If the motor is too slow, reduce or eliminate the resistance. Use of 12 volts with a 3 or 4 volt antenna will result in failure of the motor. TECHNICAL ASSISTANCE If you have any problems with this unit, please read the instructions again. If the instructions does not reference your problem or your problem is not solved by reading the instructions you may call MFJ Technical Service at 662-323-0549 or the MFJ Factory at 662-323-5869. You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road, Starkville, MS 39759; by FAX to 662-3236551; or by email to email@example.com. Send a complete description of your problem, an explanation of exactly how you are using your unit, and a complete description of your station.
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