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MASTR II VHF Exciter Re-Alignment

exciter.jpg (51376 bytes)The exciter metering jack is located just below T108. As with the receiver, use an analog meter (VTVM). All measurements are from the metering jack ground pin 8 or 9 to the pin called out in the alignment steps.

Tune T101 for maximum meter reading on pin 2.

Tune T102 and then T103 for the maximum meter reading on pin 1.

Tune T104 for a dip in meter reading on pin 3.

Tune T105 for maximum meter reading and re-adjust T104 for maximum meter reading. Then tune T106 for a dip in meter reading on pin 4.

Tune T107 for maximum meter reading and re-adjust T106 for maximum meter reading. Then tune T108 for a dip in meter reading and T109 for maximum meter reading on pin 7.

Tune T110 for maximum meter reading, and then re-adjust T108 and T109 for maximum meter reading on pin 5.

Note: These are GE’s alignment instructions. I could not get the exciter to drive the PA following the rest of their steps. I connected a watt meter and dummy load to the transmitter, my VTVM to pin 4 on the PA’s metering jack and adjusted T108 -T112 for maximum meter reading. You may have to play a bit with T108, T109 and T110 to get the exciter to drive the PA so keep an eye on your watt meter.

Move the black metering plug to the Power Amplifier metering jack (pin 8 is ground) and tune T111 and then T112 for maximum meter reading on pin 4 of the PA metering jack.

Move the black metering plug back to the exciter metering jack and re-adjust T108, T109 and T110 for maximum meter reading on pin 5.

Move the black metering plug back to the Power Amplifier metering jack and re-adjust T111 and T112 for maximum meter reading on pin 4 of the PA metering jack.

With the battery voltage at 13.4 Volts or the PA collector voltage at 12.4 Volts, set Power Adjust potentiometer R223 on the PA board for the desired power output (35 to 110 Watts) depending on your PA deck’s model.

The exciter puts out about 250 mw of RF power, adjust the ICOM frequency to the frequency of interest using a frequency counter properly connected to the exciters output.  Remember to factor in the temperature curve chart when adjusting the transmitter ICOM.