IC-2720 Mods
 

 

Read the file with the Adobe Acrobat Reader  click on the link  if you don't have this program

 

Expanded TX/RX for IC-2720/D/H and IC-2725E

Expanded TX/RX for several nationalities. Download the PDF file

 

IC-2720H- Out of band

Download the PDF file here,

ICOM IC-2720 cross band repeater

Download IC-2720 cross band repeater modification sheet

IC-2720 Adjustment Method by CS-2720 Cloning Software

Download the PDF file here, for instruction to adjust the IC-2720 with the cloning software.

 

IC-2720 RFI in mike
I have a easier fix to solving RFI in getting into the microphone.

Move the Toroid coil from near the transceiver to the remote head. I had a problem with RFI locking up the transmitter while operating at high power. The control head & mike were within 2 feet of the antenna mounted on the roof of the vehicle.

Moving the toroid coil solved my issue.

 

Reducing the RFI on microphone PTT line
While working on 2m band and high power, when the microphone is held too close to the antenna, the PTT 'hangs' in TX mode when going over to RX and/or there is sometimes no modulation during TX.

This is due to RFI on the PTT line going into the display/controller unit, and can be particularly annoying when working mobile with an antenna affixed to the front windshield (like PROCOM 'Glassfix' dualbander).

Solution :

RFI can be drastically reduced by inserting a 10 to 22nF capacitor between PTT line and ground (scratch a little bit of the PCB varnish), on the RJ-45 plug in the controller unit. See picture. If SMD capacitor not available, then try with a chip capacitor, solder the 'ground' side on big solder pad (solder of the potentiometer casing).

                   

best 73s

Jean-Jacques - ON7EQ
 

 

2720 defect parts
My 2720 burned up and here is the reason, this email is a copy of the one i received from the dealer that solded me the radio. I got a brand new one because of the defect. Just thought someone else should know. W5MRK


Hi Pat, the earlier units needed R102 changed from a 100 ohm to a 39 ohm & a thermal pad placed under the board beneath D36 (main board). This is being implemented from manufacturing now.
The "unofficial fix" done here in service is to resolder all the TX/RX diodes with silver solder and add a 16V zener diode to the driver transistor (across C93).
A bulletin from home company states their fix is improved soldering practices on the driver transistor. This is being implemented from s/n 0505701 on.

Kevin B
ICOM America, Inc.

 

Icom IC-2720 out of band mod
Remove VHF & UHF diodes in the pic 2 all up.

                
Thanks to W4RP for the pic.

Coverage is now
TX & Rx
400 MHz to 469.999 MHz
136 MHz to 173.999 MHz

This is the Australian version 2720h in the pic so there are only the 2 diodes fitted.

So I figure if you remove other if fitted you will expand the RX too.

 

 

Icom IC-2720H repeater function
To Turn On or Off The Cross Band Repeater Function. Hold The DUP LO and SET Keys for 2 seconds.

Note you have to have your VHF and UHF frequencies set First.

 

ATTENTION
The KB2LJJ takes no responsibility for any damage during the modification or for any wrong information made on this modification.