Maxtrac Power Control
Posted: Sat Nov 15, 2003 8:22 am
Several of you folks have mentioned that when the Maxtrac is taken out of its normal operating frequency range, it becomes difficult if not impossible to control the output power by means of the softpot through RSS control. It has been suggested and, I understand tried, to just hook an adjustable regulator to the controlled B+ line. Another way that will retain the over current protection already there is as follows: On the logic board, remove R810, 811. Connect a 10K pot from pin 1 of J7 to ground. From the wiper of the pot, connect a 27K resistor to pin 3 of U451. This merely replaces the analog voltage output by the D/A convertor with a user settable voltage. The voltage is taken from pin 1 of J7 because that is tx 9.6 v. That will cut the voltage to the brick off during receive. The manual indicates that the D/A convertor puts out 0 volts in receive and 4 to 7 in transmit.