Fsk Operation - Yaesu FT-901DM Instruction Manual

The distortion produced by RF envelope clipping
and filtering is less objectionable than that caused
by an equivalent amount o f audio clipping. RF
clipping causes n o incre ase in the p eak power
output, but i t does clip the peaks of the voice
waveform so as t o increase the average p ower
output.
With the p rocessor switch (located imme d iately
to the left o f the PROC LEVEL control) in the
OFF p osition (not d epre ssed ) , set the METER
switch to the ALC p o sition. Speaking at a n ormal
level, set the MIC GAIN control to the level where
the me ter indication stays in the green portion of
the meter scale . Press the processor switch a nd
adjust the P ROC LEVEL control to the position
where the ALC indication stays in the green p or­
tion of the m e ter scale while speaking in a n ormal
voic e . Op timu m se tting o f the MIC GAIN and
PROC LEVEL controls may require observation
of the transmitted signal using an oscilloscop e .
CW OPERATION
Note : The Curtis 8 043 IC Keyer Unit is buil t-in
on the FT-90 1 DM/ D E , and is an available
op tion on the FT-90 1 D/ S D models.
For electronic keyer operation, insert a three con­
ductor plug attached t o a keyer paddle into the
KEY j ack on the rear apron. Keyer spe e d m ay
then be adjusted by varying the KEYER c on trol
on the front panel.
For straight key , bug, or external electronic key e r
use, rotate t h e K E Y E R control fully c oun ter­
clockwise into the click-stop. The desired key line
may then b e inserted into the KEY j ack. Re fer
to the drawings on p age 9 for d etails of the proper
key line p lug wiring.
The transmitter may b e activated on CW by MOX ,
PTT , or by VOX (semi-break-in ) as desired . The
key-up voltage across the key terminals is 7 volts,
while the key-down current is 1 . 5 m A, so m ost
e x ternal electronic keyers m ay be used with the
F T-90 1 DM without modification .
The operator may select any power output desired
by advancing the CARR control as desired.
NOTE : Insertion of the key plug autom atically
disconnects the bias supply to the PA
tubes. Therefore , bias current will not
b e indicated wli.en the METER switch
is in the IC p osition .
AM OPERATION
AM operation of the transmitter is accomplished
by setting the MODE switch to the AM p osition
and inserting the proper amount o f carrie r with
the CARR control .
After comp leting b asic transmi tter tune-u p , place
the MODE switch in the AM position. Ac tivate
the transmi tter, and rotate the CARR control
until the meter read s . l 0 ( l 00 m A) in the IC p o­
sition of the METER switch. While speaking into
the microphone in a n ormal voice, increase the
MIC GAIN control until the m e ter indicates very
slight movement with voice pe aks. Care must be
exercised that the CARR control is not advanced
too far. Do not exceed . l 0 ( l 0 0 mA) me ter indi­
cation during AM operation or damage to the
transmitter· final amplifier tubes may resul t .
For A M reception, a n A M fi l t e r is available a s an
option.

FSK OPERATION

After completing b asic transmitter tune-u p , place
the MODE switch in the F S K position. The F S K
terminal input m a y b e c onnecte d t o t h e F S K j ack
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