Yaesu FT-901DM Maintenance Service Manual page 24

CW OPERATION
Note: The Curtis 8043 IC Keyer Unit is built-in
on the FT-901DM/DE, and is an available
option on the FT-901N/SD models.
For electronic keyer operation, insert a three con-
ductor plug attached to a keyer paddle into the
KEY jack on the rear apron. Keyer speed may
then be adjusted by varying the KEYER control
on the front panel.
GENERAL
For straight key, bug, or external electronic keyer
use, rotate the KEYER control fully counter-
clockwise into the click-stop. The desired key line
may then be inserted into the KEY jack. Refer
to the drawings on page 9 for details of the proper
key line plug wiring.
The transmitter may be 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 mA, so most
external electronic keyers may be used with the
FT-901DM without modification.
The operator may select any power output desired
by advancing the CARR control as desired.
NOTE Insertion of the key plug automatically
disconnects the bias supply to the PA
tubes. Therefore, bias current will not
be indicated when the METER switch
is in the IC position.
AM OPERATION
AM operation of the transmitter is accomplished
by setting the MODE switch to the AM position
and inserting the proper amount of carrier with
the CARR control.
After completing basic transmitter tune-up, place
the MODE switch in the AM position. Activate
the transmitter, and rotate the CARR control
until the meter reads .10 (100 mA) in the IC po-
sition of the METER switch. While 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 be
exercised that the CARR control is not advanced
too far. Do not exceed .10 (100 mA) meter indi-
cation during AM operation or damage to the
transmitter final amplifier tubes may result,
For AM reception, an AM filter is available as an
option.
FSK OPERATION
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