Communication Concepts EB104 Bias Setting - Manual

EB104 Bias Adjustment Procedure
. The supply voltage for the bias supply can be the same as the amplifier supply voltage
(48-50 volts) It is suggested that the bias circuitry on the pc board be checked out before
the RF transistors are installed. This will eliminate any damage to the RF transistors if
there is problem with the bias supply. Also, you must ensure that the pots R1-R4 are at
their minimum value of 0 volts for the initial power turn on with the RF transistors
installed. With power applied, adjust R5 to be between 7 and 8 volts. Then, while
monitoring the total current draw, adjust R1 until the current draw for one MRF150 is
150 to 200 milliamps. Then adjust R2 until the current draw is twice the draw as for R1
setting. Then adjust R3 and R4 in the same manner until the total current draw is four
times that for one MRF150. The current draw for each MRF150 should be equal.