IC706MKIIG 15M/17M Transmit Problem

By Eliot Mayer, W1MJ

Updated 8/13/05

I have received several responses to my IC706MKIIG (IC706MK2G) posting on http://www.eham.net/reviews/review/38578), which address a 15M/17M (21 MHz / 18 MHz) transmit problem. My rig, and those of two friends, "goes crazy" on these two bands while trying to adjust an external antenna tuner. The problem apparently relates to high SWR, but occurs even when the transmit power is set to minimum. It appears that, while the transmitter is "acting up", it transmits on some frequency far away from where it supposed to, and with more than the usual 5W minumum-power-setting output.

Based on responses to this review, this web page describes successful resolutions to the problem on two different rigs - mine and that of Kev Haworth, M0TNX.

W1MJ's Problem Resolution

A ham in Texas responded to my review by sending me an Icom service bulletin that appears to address this problem:

Icom Service Bulletin, "Technical Information #928" (225K pdf format)

At first, Icom America (http://www.icomamerica.com) had denied any knowledge of this problem, and wanted to charge me to fix their design problem. However, after sending them a copy of their own service bulletin, and being rather persistent, Service Manager Rodney Grim finally changed his tune and wrote, "we desire to complete customer satisfaction [sic] and if you will send this unit in, we will perfom this modification and check the unit out completely at no charge."

Icom has performed the modification, and the transmitter now works wonderfully on 15M & 17M.

M0TNX's Problem Resolution

Tue, 09 Aug 2005 16:57:25 +0100
From: m0tnx
To: w1mj
Subject: Icom fixed!


Further to my last mail, I have been in touch with Icom UK, and was aware immediately that they knew of this problem...

I was told (this is an easy fix!!) to (a) remove top and bottom case lids, (b) locate bandpass section, and (c) tighten all chassis screws holding boards to main chassis. I also went round all screws and gently nipped them tight as well.

As you look at the case lids themselves, notice they sit on some "spring" type tensioners to allow contact to earth, clean the inside of the lids with fine emery/glass paper to ensure good contact.

This worked for me, please let me know if it has helped.