Yaesu FT-757GX II, Техническое дополнение

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RF
Unit: Transmitter Circuits
A. ALC Meter Zero Set
With the transceiver tuned to 1 4 MHz, USB mode,
and with no microphone input, key the transmitter
and adjust V R1008 to the threshold point where
ALC just starts to produce meter deflection
(METER switch in ALC position).
B. TX
IF
Transformers
At 14 MHz, CW mode, with the METER switch set
to ALC, preset VR1006 to the center of its range.
Press the MOX switch and adjust T1020, T1021 and
T 1023 through T 1025 for maximum deflection on
the ALC meter. If no deflection is found at first,
set the METER switch to PO and the rear panel
FWD/REV switch to FWD. Return the METER
switch to A LC when the PO indication is maxi­
mum. If the A LC indication is overscaJe, reduce
the setting of the D RIVE control.
C. TX Power
At 14 MHz, CW mode, set the DRIVE control
fully clockwise and adjust VR1006 for 1 00 watts
output (1 0 watts for FT-757SX).
•
D. PO Meter
At 1 4 MHz, CW mode, press the MOX button and
adjust the DRIVE control for 1 00 watts output on
the external wattmeter. Set the rear panel FWD/
REV switch to FWD, and with the front panel
METER switch set to PO, adjust the FWD SET
control for internal PO meter indication of 1 00
watts.
E. SWR Turndown (Automatic Final Protection)
At
14
MHz, CW mode, connect a 16.6-ohm dummy
load (three 50-ohm loads in parallel) and a thru-type
wattmeter to the antenna jack. Rotate the DRIVE
control fully clockwise, press the MOX button,
and adjust V R1007 to the point where power
indication on the wattmeter just begins to drop.
F. CW Sidetone Level
With the AF voltmeter connected across the
speaker terminals, in a CW mode with a key
connected, close the key and adjust VR1004 for
0.3 V sidetone output on the meter.
I 00 7
I 001>
VR
I OO::'J
VR
I 00�1
VR,
001
(CW Sidetone Leve l )
Chassis Bottom View: R F Unit
TX Adjustment Locations
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