ICOM IC-706MKII Out Of Band Xmit Modification

 

By: W8CWE

 

Introduction

The IC-706MKII is a great HF through 2 Meter mobile radio from ICOM. The radio offers excellent performance on all bands. This modification provides out of band transmit capability to the radio. Once modified, you will have transmit capability on all bands and all modes with the exception of the commercial broadcast FM-Wide band.

Prior to Beginning

Before beginning, you must know that performing this modification erases ALL PROGRAMMED MEMORIES. I'm not sure exactly why this is the case. Nonetheless, if you have anything programmed into memory, you should take the time before beginning to step through them and write them down. Make sure you note any repeater offsets, etc. Also, if you have any special settings configured through the Initial Setup menu (LOCK+POWER), you should note these as well.

A Word About SMDs

In order to perform this modification, you must remove surface mount devices (SMDs). If you are not familiar with this tiny technology or if you have less than perfect eyesight, I strongly urge you to reconsider performing this modification. Minimally, if you have ANY reservation in milling about in the guts of a $1000 radio, you might wish to hand these instructions to a qualified electrical technician.

Modification Procedure

Tools Required

Preparing the Radio for Modification

  Remove power from the radio.

  Remove the power cable from the rear of the radio.

  Fold the table stand against the radio bottom (if extended).

  Place the radio on a clean, stable work surface with the front of the radio facing you.

 
Remove the Top Cover

  Remove and save the three small phillips head screws across the center of the top cover. Do not remove the four speaker screws.

  Remove the two phillips head screws securing the rear of the top cover to the side of the radio chassis.

  Carefully pry the top cover from the rear of the radio.

  Disconnect the speaker leads at the two-pin speaker connector.

 
Perform the Modification

  Near the top-right of the main circuit board, you will find an oblong crystal can. Directly below the right edge of this can are two SMD diodes inside of a small white box. Immediately to the left of these devices is a part number (B4916XX).

  Remove the Left diode in the white box.

  Move about an inch to the left of the device you just removed.

  Locate the test point CP3.

  To the left and above this test point is another white box with two vertical SMDs. Remove the Left diode in this white box.

Return the Radio to Operation

Return the unit to normal operation by reconnecting speaker and installing the top cover. Reconnect the power cable and apply power to the unit. It will come up in the default (out-of-the-box) configuration. Using the notes you took earlier, reconfigure and reprogram your memory channels. Your IC-706MKII can now transmit from 0.500.00 Mhz to 200.000 Mhz (minus the commercial FM-W broadcast band).