LOW AUDIO FROM SPEAKER MIKE ON IC2A, 3A, 4A OR O2AT HAND-HELDS
If you own one of the IC2A, 3A, or O2AT series Hand-helds,
you may be interested in reading on.  I know my hearing is
pretty good, but have you ever tried to listen to the audio
coming out of your speaker mike on the above ICOM's? For the
most part, it's pretty low.  I may be the last guy to figure
out a cure for this, but here it is anyway.  On the O2AT,
etc., there is a groove on the back near the top of the rig
that is just the right size to accept the HM9 speaker mike
turned 90 degrees so that the mike plug fits in that groove
in the rear of the rig.  Thus alllowing all the audio to be
heard from the internal speaker of the rig, usually much
better than the speaker mike.
Now, in the case of the 2A series, etc., the fix is more
complex.  These rigs don't have that handy groove built in,
so I decided a groove had to be made to accept this
configuration.  I thought long and hard about a minute,
before getting the "Dremel" out and making my own slot or
groove.  It works well on both hand-helds I have.  In fact,
you can hook up an external speaker for even more loudness in
the auto.  So, give it a try or see me for a demo.

                        Another Icom IC02 Modification

     The following method of modifying the Icom IC02 is an alternate
to the IC02.MOD file.  This one should give you PL out of band without
jumpering 5 VDC to the tone chip.  Use 1N914 or equivelent when adding
diodes.

1.  On the logic matrix, remove D402 and D403.

2.  Add D402, D403 and D404 with the cathode at 4 o'clock and the anode at 12
o'clock.

3.  Retune the VCO to cover your desired frequency spread.  My 02AT did not
want to go beyond 163 MHz.  I have a friend who was able to get his to the low
170s.

4.  To jump from 140 to 150 or from 150 to 160 (or vice versa) you must "tune
across" the boundry, in the same way that you do for an unmodified 02AT.  For
example, key in 149.995 and then move up until you are in the 150s.  You can
then enter any 150 MHz frequency (starting with the MHz).

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The ICOM Family of Hand-Held Radios (02/03/04 AT) are well suited
for packet radio given the many available power supply options.

The big problem is getting the PTT to operate " CLEANLY " while
not compromising the audio level from the TNC when using the resistor
or resistor/capacitor interfaces suggested in some manuals.

I am using the ICOM HS10-SA Vox unit to interface the ICOM 02/04 AT
here.It has worked somewhat well for some time but I was always plagued with
a MINIMUM 200 msec transmit "hang " delay until I tore it apart for
examination and correction.

The small " delay " pot on the front of the unit is in series with a
2.2 Megohm resistor (R-19 on the board). The adjustable pot is also
about 2 megohms as well. This combination allows a MINIMUM VOX "hang" transmit
delay of 200 msec.

By identifiying the solder connections for R-19 on the back of the PC board
and placing a low value resistor ( or jumper )  in parallel....I was able to
achieve a ZERO "hang" transmit delay time with the delay pot in the FULL
COUNTER-CLOCKWISE position. The minimum 200 msec delay has been defeated.

 DOWNLOADED AND REALIGNED FROM THE PACKET NETWORK BY BOB G0LBQ - N6XDI.