Yaesu FT-902DM, Instruction Manual

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The distortion produced by RF envelope clipping
and fi ltering is less objectionable than that caused
by an equivalent amount of audio clipping. RF
clipping causes n o increase in the p eak p ower
output, but it does clip the peaks of the voice
w aveform so as to increase the average p ower
output.
With the p rocesso r switch (located immediately
to the left of the PRO C LEVEL control) in the
O FF p osition (not depre ssed), set the ME TER
switch to the ALC position. Speaking at a n ormal
level , set the MIC GAIN control to the level where
the me ter indication stays in the green p ortion of
the meter scale . Press the processor switch and
adjust the P RO C LEVEL control to the position
w here the ALC indication stays in the green p or­
tion of the meter scale while speaking
ii1
a n ormal
voice. O p timum setting o f the MIC GAIN and
P RO C LEVEL controls may require observation
o f the transmitted signal u sing an oscilloscope .
CW
OPERATION
N ote: The Curtis 8044 IC Keyer U nit is built-in
on the FT-902DM /D E, and is an available
option o n the FT-902D/SD models.
For electronic keyer operation, insert a three con­
ductor plug attached to a keyer paddle int o the
K EY j ack on the rear apron. Keyer speed m ay
then b e adjusted by varying the KE YER control
o n the front panel.
For str aight key, bug, or extern al elect roni c keyer
use, rotate the KEYE R control fully counte� ­
clockwise into the click-stop. The desired key line
may then b e inserted into the KEY j ack. R efer
to the drawings on p age 9 for details of the proper
key line plug wiring.
The transmitter m ay be activated on CW by MO X ,
PTT, o r b y VO X (semi-break-in) a s desire d . T he
key-up voltage across the key terminals is
7
volts,
while the key-down current is 1 . 5 mA, so m ost
externa l electronic keyers m ay b e used with the
FT-902DM without m odification .
The op erator may select any power output desired
by advancing the CARR control as desired .
NO TE : Insertion of the key plug automatically
disconn ects the bi as supply to the PA
tubes. Therefore , bias current will not
b e indicated when the METER switc h
is in the IC p osition .
A M OPERATION
AM operation of the transmitter is accomplished
by setting the MO DE switch to the AM position
and inserting the proper amount of carrier with
the CARR con trol.
After completing b asic transmitter tune- up , place
the MO DE switch in the AM position. Activate
the transmi tter, and rotate the CARR c ontrol
until the meter reads . 1 0 ( 1 00 mA) in the IC p o­
sition of the METE R switch. W hile speaking into
the microphone in a normal voice, increase the
MIC GAIN control until the meter indicates very
. slight movement with voice peaks. Care must b e
exer cised that t h e CARR control i s not advanced
too far. Do not exceed . 1 0 ( 1 00 mA) meter indi­
cation during AM operation or damage to the
transmitter fi nal amplifier tubes may result.
For AM recep tion, an AM filter is available as an
op tion.
FS K OPERATION
After completing b asic transmitter tune-up, place
the MO DE switch in the FSK p osition. The FSK
terminal input may be connected to the FSK j ack
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