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PK-88 OPERATING MANUAL
This procedure is is divided into separate sections for FM and SSB radios.
Follow these steps exactly in order to:
Verify that your radio and PK-88 are connected as shown in Table 2-1
earlier in this manual, and Figure 2-1 below.
Connect the PK-88's AFSK audio output to your radio's microphone
receptacle or auxiliary input jack.
Adjust the PK-88's internal output-level control (VR1) to obtain proper
modulation.
Take the receiver's audio output from an earphone plug or speaker jack
and feed the audio directly to the PK-88.
Insert the eight-pin connector into J2 on the PK-88's rear panel and connect
the microphone plug to your radio's microphone jack.
2.8.1
PTT (Push-to-Talk) Configuration
The PK-88 is configured at the factory for Positive PTT. This seems to work
with most modern radios. However, you can, change the polarity of the PTT
configuration as needed. Follow these steps:
Remove four screws from the sides of the PK-88 and lift off the cover.
Viewed from the front, jumper post JP5 is located at the rear left-hand
side of the board in front of J4. JP5 is a three-pin jumper post on
which you install a slip-on jumper to connect the center pin to one of
the outside pins.
To change to negative PTT polarity, move the jumper block to the opposite
center-end pair of pins.
Reinstall the cover and replace the four side screws.
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 Jl. Jumper post JP3, located in front of Jl, 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 opposite position.
The WA7MBL packet BBS programs require that JP3 provide DCD high only in the
connected state.
See the PK-88 schematic diagram in the Appendices section for further details
on JP3.
2-8
INSTALLATION
PK88-26
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