Quick & Dirty Data Interface
============================

Designed by: Some guy in a basement

Jan 14, 1998

This interface is functionally identical to the unit described in the
PD-20x literature.  It uses less parts, and it's small size allows it
to be built around a sub-miniature earphone jack inside a hand-held
scanner, or enclosed within a 9-pin gender changer case.

The designer has tested it with 2400 baud POCSAG; it has not yet been
tested with MDC-4800 or Mobitex.  It must be used with the scanner's
discriminator output.

As of this date, I have not personally tested this circuit.

Send feedback to
sir-valence@geocities.com

Spectrum Analyzers web site
http://spectrum.base.org/


Parts list:
-----------
(2) 100k, 1/8w resistor
(1) 15k, 1/8w resistor
(1) 3.6k, 1/8w resistor
(1) .67 uF capacitor
(1) 2N4401 transistor


Serial port pinouts:
--------------------
COM    25-pin   9-pin
PORT   Conn     Conn
----   ------   -----
CTS    5        8
DTR    20       4
GND    7        5


                          .67 uF          2N4401
                        |---| |---|           C       3.6K
                        |         |          /----|---/\/\/---o DTR
                        |         |      B |/     |
Discrim  o----/\/\/-----|--/\/\/--|--------|      |
input          100k         15k   |        |\     |-----------o CTS
                                  |          \E
                                  |           |
                                  |           |
                                  |---/\/\/---|
                                      100k    |
                                              |
                                              |
                                         GND  o