Kenwood TS-440S - Manual (Page 21)

3-8. AFSK
3-8-1. Reception
Note:---------------------
An RTTY terminal is required to receive and dis-
play/print the RTTY signal.
1. The AFSK mode utilizes the LSB carrier frequency,
which conforms to international conventions.
2. When the optional YK- 88 C filter is installed, the nor­
mal receiver bandwidth is 500 Hz when the SELEC­
TIVITY switch is set to the AUTO position, and the
MODE switch is in AFSK.
The accompanying diagram illustrates the relation­
ship between the carrier and the passband width.
3. The demodulated AFSK signal is sent from the
AFSK OUT terminal on the rear panel.
4. This completes the preparation for using the AFSK
mode.
Note: ----------------------------------------------------------------------------
Before connecting the terminal you should review the
contents of the instruction manual provided with that
terminal unit.
Monitor
display
AFSK IN
AFSK keying signal.
TS-440
RTTY device
AFSK receive signal
AFSK OUT
The figure below shows the frequencies relationship.
2295Hz
3-8-2. Transmit
Note:
Key down periods of 1 hour will require a cool down
period of approximately 30 minutes. The PS-50
heavy-duty supply is recommended for continuous
duty transmission.
1. Ensure that your terminal is set up for AFSK type
keying.
2. Connect the terminal units AFSK output jack to
TS-440S AFSK IN jack, and the terminal unit's
AFSK input jack to the TS-440S AFSK OUT jack
on the rear panel of the transceiver. The terminal
units standby (PTT) terminal should be connected
to the standby terminal on the REMOTE connector
of the TS-440S. (See page 11 for the REMOTE ter­
minal pin configuration.)
3. Place the MODE key on the TS-440S to AFSK, and
the Meter switch to ALC.
4. To transmit, either place the SEND/REC switch on
the TS-440S to SEND, or use the PTT signal from
your terminal unit.
5. When using AFSK, you can also apply your trans­
mit signal tones to pin number 1 of the microphone
connector, if you do not wish to use the two jacks
on the rear of the TS-440S. To adjust the power
output in AFSK, increase or decrease the MIC gain
control setting. A mid-scale ALC reading will yield
full power output.
Notes: --------------------------------------------------------------------------
1. AFSK operation requires terminal unit designed to
supply this type of operation. You cannot use FSK
tones with an AFSK jack!
2. The AFSK oscillator circuit should provide audio
tones of 2125 and 2295 Hz. Lower tones may
cause spurious output due to the higher harmonic
content present with these lower frequencies.
3. The TS-440S and RTTY terminal unit should use
separate power supplies, in order to prevent RFI
(Radio Frequency Interference).
4. During AFSK mode operation, the microphone
switch should be OFF or ground pin No. 9 of the
ACC 2 jack, or the microphone disconnected, if you
are using the AFSK jacks on the rear panel.
5. The AFSK input level should be less than 100 mV.
3-8-3. AMTOR operation
For AMTOR operation, you should reverse the trans-
mit/receive input polarity on your AMTOR terminal,
since AFSK on the TS-440S operates in the LSB mode.
If you cannot reverse the polarity, you should select
the USB mode on the TS-440S.
During AMTOR operation, the microphone switch
should be OFF, or ground pin No. 9 of the ACC 2 jack,
or the microphone disconnected, if you are using AFSK
IN/OUT jacks on the rear panel.
3-9. OPERATION WITH A LINEAR AMPLI­
FIER
The TS-440S may be operated with any conventional
linear amplifier which will accept up to approximately
125 watts of RF drive, has a low current DC operated
keying circuit, and returns approximately -8 to -1
VDC ALC back to the exciter. Please note that in ord­
er to operate full QSK (FULL break-in) the linear ampli­
fier must also be QSK capable.
Refer to the REMOTE connector diagram on page 11
and section 5-8-10..
Initial linear amplifier tune-up should be performed with
the TS-440S set for approximately 50 watts output
to reduce wear and tear on both the linear, and the
TS-440S. Use of a dummy load is strongly recom­
mended, since the bands are already sufficiently
crowded.
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