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PK-88 OPERATING MANUAL
2.8.2
Data Carrier Detect (DCD Pin 8) Jumper JP3
Certain applications may require that the connected state raises the Data Carrier Detect
(DCD) signal on Pin 8 of the RS-232 interface at rear-panel connector J1. Jumper post
JP3, located in front of J1, between integrated circuits U4 and U5, is factory set so that
DCD Pin 8 is permanently pulled high.
If DCD is required active in the connected state only, move the JP3 jumper plug to the op-
posite position.
The WA7MBL packet BBS programs require that JP3 provide DCD high only in the con-
nected state.
See the PK-88 schematic diagram in the Appendices section for further details on JP3.
2.8.3
FM Installation and Adjustment
Disconnect power before making any other connections.
1.
Remove four screws from the sides of the PK-88 and lift off the cover.
2.
Connect the PK-88 and FM radio as shown below in Figure 2-1.
3.
Apply power to your computer and PK-88 and start your terminal program.
4.
Connect the radio to a dummy load; be prepared to monitor your transmissions
with another nearby radio.
5.
Enter the Calibrate mode by typing
Ignore the 'zeros' scrolling down the left side of your screen. The self-contained 7910 modem chip
does not require calibration or tone adjustments. The 'zeros' appear only to show that the PK-88 is
in the 'Calibrate' mode for the purpose of keying the transmitter and applying steady-state tone
modulation for transmitter adjustment.
NOTE:
In the Calibrate mode only, the
The
[SPACE BAR]
rity, the lower-pitched tone) to 'Space' (Start Polarity, the higher-pitched tone). The
PK-88's transit watchdog timer circuit unkeys your transmitter automatically after 60
(sixty) seconds. As you perform the following adjustments, unkey periodically, then
rekey the transmitter by typing [K].
CAL
[K]
key toggles the transmitter PIT line on and off.
toggles the PK-88's AFSK tone generator from 'Mark' (Stop Pola-
2 - 8
[RETURN].
INSTALLATION
PK-88 - 24
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Troubleshooting
