7.3 PA Bias
7-13
7.3 PA Bias
PA bias is adjusted after replacing PA transistor on PA and DRV boards. The adjustment
is made with PA IN connector disconnected.
Board Model Meter Connection Adjuster Rating
PA (05P0735) FS-1570T
Cut L4 and connect an ammeter
across L4.
R25 200 mA
DRV (05P0738)
Cut L4 and connect an ammeter
across L4.
R25 100 mA
PA (05P0739)
FS-2570T
Cut L1 and connect an ammeter
across L1.
R16 200 mA
(1) 05P0735 board (PA, FS-1570T)
R33 (Ic ADJ): Collector current of the PA is adjusted by R33 so that the readout of Ic at
output power adjustment is equal to the actual collector current.
R37 (Vc ADJ): Collector voltage of the PA is adjusted by R37 so that the readout of Vc
at output power adjustment is equal to the actual collector voltage.
A
+
-
PA BIAS ADJ.
(R25, 200 mA)
L4
PA IN (J2)
Remove the connecter
for BIAS adjustment.
Ic ADJ. (R33)
Vc ADJ.
R37
Wire is as short and
heavy as possible.
Fig.7.3.1 150 W PA, 05P0735
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