POWER AMPLIFIER A2A1 ALIGNMENT
The alignment procedure is to be used in either of these situations: (1) the performance test calls a potentiometer out of adjustment, or (2) one of the following is
Overshoot Control AR3, AR4
Buffers ART, AR2
Power Transistors Q3, Q6, Q10, Q11
Transformers T1, T2, T3, T4, T5
The procedure consists of a preliminary setup and an adjustment procedure.
R1 = GAIN ADJUST
R13 = BIAS ADJUST
R24 = +30.5 VDC ADJUST
1. Remove the power amplifier from the amplifier/coupler.
1. Monitor TP-3 with DVM, close PTT. On bottom board adjust R24
R34 = ALC REFERENCE
Connect the test setup as shown in figure 9-3, however, to
for +30.5 + 0.5 vdc. Open PTT.
not connect the of coax cable at this time. The of coax cable
connected at A1J2 will be connected directly to the coaxial
2. On the 18 pin extender cable remove the jumper lead between
the two test points. Insert a dc ammeter in place of the jumper and
select a range of at least 100ma. Ensure that positive lead is
2. Set dc power supply (7 amp) to +24.5 vdc. Set step
inserted into test point closest to the connector on the PA module.
attenuator to 10 db.
Close PTT only long enough to adjust R13 (top board) for a reading
3. Set ANT SEL to 50 ohm (bypass), VOLUME to on.
FREQUENCY KHZ to 29, 999.1, SB to USB, MODE TO
3. Adjust the rf signal generator to 29.9999 MBz at +22 dbm (150
mw). Refer to Note 7 on figure 9-3. Connect the rf coax cable to
A1J1 and the rf signal generator. Adjust R1, GAIN ADJUST
(topboard), for a reading of 27 mw on the power meter.
4. With DVM, monitor E8. Close PTT, adjust R34 (bottom board) for
a reading of +13.5 + 0.5 vdc.
5. Open PTT, disconnect test equipment.