Yaesu FT-901DM Maintenance Service Manual page 81

SERVICING
EQUIPMENT REQUIRED
(a)
(6)
RF Signal Generator: Hewlett-Packard Model
606A or equivalent, with one volt output
at 50 Ohms, and frequency coverage to 30
MHz.
Vacuum Tube Voltmeter (VTVM): Hewlett-
Packard Model 410B or equivalent, with an
RF probe good to 40 MHz.
Dummy Load: Yaesu model YP-150 or equiv-
alent, with 50 Ohm non-reactive load imped-
ance rated to 150 watts average power.
AF Signal Generator: Hewlett-Packard Model
200AB or equivalent.
A general 'coverage receiver covering the fre-
quency range from 3 to 30 MHz with a 100
kHz calibrator.
A frequency counter, Yaesu Model ¥C-500
or equivalent, with resolution to .01 kHz
and frequency coverage to 30 MHz.
1. S-METER SENSITIVITY ADJUSTMENT
Place the transceiver in the receive mode and
connect a signal generator to the antenna terminal
of the transceiver. Set the signal generator to
14200 kHz with an output of 6 dB. Tune the
transceiver to 14200 kHz for a maximum reading
on the S-meter. The S-meter should just start to
rise with a 6 dB input. If no deflection is observed,
adjust VR4o2 to obtain a slight meter deflection.
Apply 100 dB input to the antenna terminal;
the S-meter should read $9 + 60 dB. If not, adjust
VRgor- VRao1 and VR4o2 are located on PB-
1704.
When the transceiver is tuned to 14200 kHz, the
100 kHz calibrator signal will indicate approxi-
mately S9 + 10 dB when MARK switch is acti-
vated.
Select Switch Board MJ:(PLL Unit
Reject/Width Board
(PB-1722)
Crystal Unit
(pp-1711) 18
Mus (FM Unit
MJ: (Carrier Unit)
Memory Unit _
(PB-1787)
Mus (IF Unit)
Mus (Filter Unit)
Keyer Unit _f
(PB-1728) |
MJ:(NB/Proc. unl
MJ:(Rect.A Unit)——
MJ. (Rect.C Unit)
(PB-1718)
Tune Board
| (PB-1720)
MJiz (VCO Unit)
—Trimmer A Board
(PB-1723)
—Trimmer B Board
(PB-1724)
Trimmer © Board
(PB- 1092-3330)
MJ io (RF Unit
PA Board
(PB-1715)
Diode Switch Board
(PB-1726)
Rect.B Board
(PB-1712)
Capacitor Board
(PB-1713)
Bottom View
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