USING THE ICOM-2E AS A TRANSCEIVER FOR PACKET RADIO
        ---------------------------------------------------

The ICOM-2E handheld is equipped with 2 connectors for use of an external microphone/speaker (type HM9).
These connectors can also be used for packet radio. Either a special plug (with both a thick - 3 mm - and a thin - 2 mm - plug) is necessary, or 2 separate "earphone" jacks of respectively 3mm and 2 mm thickness.
As shown in the schematic diagram below, the "tip" of the 3 mm jack is
connected with AF input to the packet TNC, whereas the "tip" of the 2 mm jack carries (via a relay-contact) the AFSK output of the TNC.
Just as in the HM9-microphone/speaker, both a small capacitor (470 pF) and a resistor (33 k) have to be put between the audio (AFSK) line and the ground. The relay contact replaces the HM9's PTT contact.

AF from receiver to TNC

0--------------------------------------------------------|
                                                   ------|-\
Ground                                      ------|-o  |o  | plug 3 mm
0--------------------------------------------|     --------/
       |            |                        |
       |           ---                       |
      ---470pF     | |33k                    |     --------\
      ---          | |                      ------|-o  |o  | plug 2 mm
       |           ---                             ------|-/
       |            |                       /            |
0------------------------------------------/  -----------|

  AFSK from TNC to transmitter            relay contact


 PTT ------        ------
0----|    |--------|    |-------------> +12V
     ------   |    ------     |
     10k      |    22 k       |
              |            ----
              |           /emitter
              |         |/ 
              ----------|   BC557
                        |\ 
                    coll.  \------------
                           |          |
                       ---------     ---
                       |relay  |     / \
                       ---------     ---
                           |          |
                           -----------------> ground

Hans PA3ESZ @ PA3EAE


                   IC2E on packet
                   ==============

The IC2E can be used successfully on packet. This is how to achieve it.

TNC                             RIG
~~~                             ~~~
PTT-----------4.7K-------- TIP OF SMALL JACK

TX AUDIO------0.1MF------- TIP OF SMALL JACK

GROUND-------------------- BODY OF BOTH JACKS

RX AUDIO------------------ TIP OF LARGE JACK

This arrangement works with most TNC2 type clones, but it has not been tried on the PK88.

Another possibility would be to use a 1 to 1 audio isolating transformer.
This is a suggestion on how to connect it up:

RX AUDIO---------TIP OF LARGE JACK
GROUND-----------BODY OF LARGE JACK
GROUND-----------TRANSFORMER PRIMARY
TX AUDIO---------TRANSFORMER PRIMARY
PTT--------------TRANSFORMER SECONDARY
                 TRANSFORMER SECONDARY---------TIP OF SMALL JACK

When the PTT line goes low, it makes the Tx connection for the IC2E.

Julian G6LOH @ GB7BIL


                  IC2E on packet
                  ==============

Just another note about using the IC2 with TNCs.
On Kantronics TNCs this can be enabled by using an internal jumper.
No external cross-wiring of PTT and Audio is required.

On some IC2's (like mine) the value of the PTT pull-down resistor needs to be lower for reliable PTT operation. Try 3.3k instead of the 4.7k.

Also, don't forget that the IC2 is NOT intended for use off 12v, use a 9v reg to supply it or (especially on older models) you may lose the PA!

73 Paul G4BKI @ GB7BIL


PORTED AND REALIGNED FROM PC TO AMIGA FORMAT BY BOB G0LBQ - N6XDI.