There are four adjustable trimmer resistors (R6, R9, R15, R18) on the all band PA board.
These trimmers define the bias current of the driver and power amplifier MOSFETs.
All the measurements during the adjustment is done by using the LCD current display.
The driver stage bias current is 2 x 0.03 A = totally 0.06A and the final stage bias current is 2 x 0.10 A = totally 0.20 A

- Keep the supply power OFF
- Initially turn the trimmers R6, R9, R15, R18 fully counter-clockwise for zero bias
- Double-check the zero bias by measuring the resistance across C5, C7, C12, and C14, the reading should be below 10 ohms.

Note. The trimmers are multiturn models. When turning the trimmers the bias current is not increasing in the beginning. Continue turning until you see an increase of the reading and then fine tune the bias current. Typical trimmer position is approximately in the middle.

1. Set the drain current selector jumper J7 on the board in to the DRV position
2. Switch ON the power (Current limited power supply recommended)
3. Select CW mode by pushing the MODE button
4. Select Drain Current display (ID -.--A) by pushing the DISPLAY button
5. Press the mic PTT to activate the bias current
6. Turn the trimmer R6 clockwise until the LCD ID reading indicates 0.03 A ± 0.01 A
7. Turn the trimmer R9 clockwise until the LCD ID reading indicates 0.06 A ± 0.01 A

Driver stage bias current reading 0.06 A after the adjustment

Note. The trimmers are multiturn models. When turning the trimmers the bias current is not increasing in the beginning. Continue turning until you see an increase of the reading and then fine tune the bias current. Typical trimmer position is approximately in the middle.

1. Set the drain current selector jumper J7 on the board in to the PA position
2. Switch ON the power (Current limited power supply recommended)
3. Select CW mode by pushing the MODE button
4. Select Drain Current display (ID -.--A) by pushing the DISPLAY button
5. Press the mic PTT to activate the bias current
6. Turn the trimmer R15 clockwise until the LCD ID reading indicates 0.10 A ± 0.02 A
7. Turn the trimmer R18 clockwise until the LCD ID reading indicates 0.20 A ± 0.02 A

Finally leave the drain current selector jumper in to the PA position

Final stage bias current reading 0.20 A after the adjustment

Equalizing the RF output on each band

On the all band PA board there is an input attenuator (IC1 and related resistors) which can be adjusted individually on each band to equalize the output RF power. This can be done with the user interface.

Note, follow exactly the sequence
1. Go to the desired band
2. Select the Tune mode by MODE button
3. Select the PWR -.-W display by DISPLAY button
4. Push and keep the PTT down. While the PTT is down push and keep the green PWR button down. The LCD will show the current output power and the gain in desibels e.g. -1 dB
5. Turn the VFO knob until the LCD shows desired output RF power (approx. 10W)
6. Release the PTT and the PWR buttons

This PA gain setting is saved individually at all 9 ham bands to the non volatile memory when you switch OFF the TRX2A. Note, the settings will be saved only when switching OFF the power with the green PWR button, not with the power supply switch.