Modifications for the Icom IC-746

Picture(s) of Icom - IC-746

19-07-1998 IC-746 out of range TX/RX (1 Kbytes)
11-12-1999 IC-746 Modification
25-10-2000 Extended RX/TX for IC-746 (0 Kbytes)
02-12-2000 Separating the Tx and Rx lines (1 Kbytes)
02-07-2001 Power mod for the IC-746 (0 Kbytes)
20-10-2001 Solutions for chip blowing with mPC (33 Kbytes)
13-01-2002 Monitor Audio Output Too Low (1 Kbytes)
25-01-2002 Schematic for ICOM CI-V Option (16 Kbytes)

IC-746 Modification
Author: John Schmitz NS8E


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

Additional information.

After having put a forward reading watt meter on my 746 i have found that there is NO loss of power due to this mod. It is still putting out the full 100 watts when you have a good match (5-100 on SSB and FM and 2-40 on AM).

I have also discovered that the TX was NOT opened up above 54MHz to 60MHz the top end of the 6 meter band switch on the 746.

The only effect i have noticed is that sometimes while using the built in antenna tuner in manual tune the LCD display sometimes blinks or lights up with all functions showing or sometimes disappears below the line.
Also the band edge beep function option no longer works because with wide open TX there are no more band edges.
One must be carefull to stay within their operator band privileges. These are the only adverse effects i have noticed with Mr. Schmitz mod.