Yaesu FT-991A, Technical Supplement

Page: 25 / 131

Alignment
ALIGNMENT-14
FT-99
1
Technical Supplement
V-U PA Unit Adjustment
Preparation

Connect the Microphone to the front panel MIC
jack.

Connect the 50-Ohm Dummy Load and Watt-
meter to the “144/430 MHz” ANT jack.

Disconnect the coaxial cables from J4501 and
J4502 on the V_U-PA Unit, then terminate J4501
and J4502, each with a 50-Ohm resistor.

Disconnect the jumper plugs from J4505, J4506
and J4507 on the V_U-PA Unit.

Disconnect the red cable from J4503 on the V_
U-PA Unit.
Pre-Drive Stage Idling Current Adjustment

Connect the DC ammeter to J4505 on the V_
U-PA Unit.

Press and hold the PTT button, while adjust
VR4501 so the DC ammeter reading is “40 mA
(±5 mA)”.

Release the PTT button.

Disconnect the DC ammeter from J4505.
J4501 J4502
J4505 VR4501 J4506
J4507 J4503