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Subject: IC-746 Modification
From: "Schmitz, John" 
Date: Fri, 13 Aug 1999 07:14:49 -0400


IC-746 Mod.

Remove the twelve screws holding on the bottom cover.  With the Radio
laying flat on it's top remove the bottom cover.  Turn the radio so
that the front panel is to your left and the antenna connectors are to
your right.  Locate the IC labeled "ICOM HD6433042SF".  About 3/4 of an
inch to the right is a vertical row of diodes.  The left hand column of
diodes has 7 diodes (14 possible spaces).  The right hand row is full
with 14 diodes.  Remove the diode in the 6th space from the top in
the left hand column.  DO NOT remove anything from the right hand
column.  This should get you TX from about 100KHZ to 60MHZ and 118MHZ
to 176MMZ.  Do this totally at your own risk. Never, ever transmit out
of the ham bands or your privileges..

John Schmitz NS8E


-------------------

Editor,

I think that there is a new configuration for the IC-746 diodes which open
up certain bands.  I would like the opportunity to mention that in the mod
that I sent in before.  I do not have the answer to it, so I would like to
re-write the mod that you currently have.

I've attached below what should be a better mod page for the IC-746

John
NS8E
---------------------------------------------------------------------

IC-746 Mod.

This is the mod for an IC-746 with the diodes in the 1, 2, 4, 6, 9 and 14
position and the description below explains this.

! IMPORTANT !

There seems to be new version of the diode pattern out there with diodes in
the 1, 3, 4, 6, 7, 10, 11, and 14 position and the mod DOES NOT work for
this pattern.  If you find this pattern after reading the mod below, DO NOT
try it.  It DOES NOT work.  If I find the mod for that pattern I'll try to
get it posted here also.

Remove the twelve screws holding on the bottom cover.  With the Radio laying
flat on it's top remove the bottom cover.  Turn the radio so that the front
panel is to your left and the antenna connectors are to your right.  Locate
the IC labeled "ICOM HD6433042SF".  About 3/4 of an inch to the right is a
vertical row of diodes.  The left hand column of diodes has 7 diodes (14
possible spaces).  The right hand row is full with 14 diodes.  Remove the
diode in the 6th SPACE from the top in the left hand column.  DO NOT remove
anything from the right hand column.  This should get you TX from about
100KHZ to 60MHZ and 118MHZ to 176MHZ.  Do this totally at your own risk.
Never, ever transmit out of the ham bands or your privileges..

John Schmitz NS8E



---------------------------------------------

At a Ham Fest last year I purchased a Kenwood MC-60 microphone with the
intention of using it with my ICOM IC-746 transceiver.  Figuring out
the microphone and PTT connections was pretty straight forward.
However making the Up and Down switch work with my ICOM was not that
straight forward.  Kenwood uses separate lines for the Up and Down
functions while ICOM uses one.  Having other things to do at the time,
I simply hooked up the microphone and the PTT switch and used it
without the Up/Down function.

Now I'm sorry I took so long to get back to the project.   After doing
some investigation I figured out (using the original ICOM microphone)
that the Up function on the ICOM was achieved by grounding pin 3 on the
ICOM microphone connector.   The Down function was done by grounding
pin 3 through a 470 ohm resistor.  The solution was simple.  Add a 470
ohm resistor across pins 3 and 4 on the back of the connector in the
base of the MC-60 and connect pin 4 of the microphone to pin 3 on the
ICOM.  (See figure)



 David M. Hitchner - hitchner@home.com Baton Rouge, LA

 KD5EIS - kd5eis@arrl.net

 

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