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PK-88 OPERATING MANUAL
2.8.4
SSB Installation and Adjustment
Installation and adjustment of the PK-88 with SSB radios is usually simpler
and more direct than with FM equipment. You will use the same kind of cables
and connectors that you use with your FM gear.
Digital modes with an SSB radio require some different settings of the radio's
operating controls for proper packet operation. Be sure to observe the
following precautions:
Set VOX to OFF.
Set speech compression to OFF.
Set AGC to FAST (if available).
Disconnect the ALC cables between your SSB radio and any external
RF amplifier you wish to use in packet radio service.
NOTE:
Make all connections with power off.
If your radio has a phone patch input and external PTT connections, the PK-88
AFSK output can be connected to those input jacks, leaving the microphone jack
for normal service. However, some microphones are connected at all times
(regardless of the PTT line's state. In this case, disconnect the microphone
to prevent inadvertent loading of the audio input circuit. If the phone patch
jack has a series isolating resistor, your microphone can remain connected.
1.
Connect the PK-88 and SSB radio as shown in Figure 2-1.
2.
Apply power to the PK-88 and your computer and start the terminal
program.
3.
Connect your SSB radio to a dummy load.
4.
If your SSB radio has a 'monitor' facility, i.e., an audio output that
lets you listen to the audio signals entering the microphone or phone
patch jacks, turn that monitor circuit on.
5.
Set the radio MODE selector to either USB (upper sideband) or LSB (lower
sideband). Because packet radio uses NRZI data on the radio link, the
sideband used does not affect the data sense or polarity. However, the
radio's tuning calibration or frequency display will vary depending on
which sideband is selected.
6.
Set the radio's meter switch to the 'ALC' position. If the radio doesn't
have an 'ALC' indication, set the meter switch to 'IP' to read output
device or plate current. If an output device or plate current reading
isn't available, set the meter to indicate power output.
7.
Set the PK-88's TONE value to either TONE 0 for the low tone pair or TONE
1 for the high tone pair.
2-11
PK88-29
INSTALLATION
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