Icom Radios

ICOM CIV and Yaesu CAT Control USB and USB to Serial cables

Many of the cheaper USB ICOM CIV cables use the counterfeit Prolific chips and don’t always work reliably, especially with Windows 8 and 10.    Ebay store bluemax49ers offers cables at reasonable prices that work and also provides support for them.  I’ve also experienced more severe issues with Yaesu cat control using USB to serial converters and recommend purchasing your cables from this Ebay vendor.  If you have to use a USB to serial for serial control, look for a FTDI chip based converter.  It may cost more but you will have less headaches.

A Death Threat on your ICOM 706MKIIG HF/6 meter PA

Heard horror stories of the 706MKIIG having blown finals and there are no OEM replacements available?   There is an issue that needs to be addressed that might save yours from an untimely demise. This doesn’t apply to a 706MKII so you don’t have to check it.  I am not sure about an original 706.  Over time the repeated insertion of the PL259 pushes the center pin back until it shorts out against the radio frame. This only happens on the HF/6 connector.

Remove the top cover (the one with the speaker).  At the rear of the radio where the HF/6 SO239 connector is located, remove all the screws on the circuit board covering that area and gently lift up slightly and slightly to the side. Do not try to remove it entirely, just enough to look into the area at the back of the SO239.  See the center pin with the wire soldered to it?  How close is it to the extruded frame of the radio to the rear?  Almost touching?  Mine was. There isn’t much space between the pin and the frame when the pin is properly seated.

The Fix – Push the center pin forward into its original position. Insert an insulator of some sort behind the pin so it cannot move backwards.  I use a piece of Teflon block wedged behind the pin.  Reassemble and no more worries on shorting out your PA.

ICOM/YAESU/KENWOOD Power Output Issues

Recently one of my friends called and said his Icom was shutting off on transmit.  I told him to change out his power cable.  He argued with me it was not the problem.  He lost that argument after I convinced him to try a spare power cable.  This was the third time I have seen this issue. The first time I experienced it with a 706MKIIG I noticed the fuse holder got hot.  A little reading uncovered what was causing it.  The crimps on the wires to the fuse holder clips develop resistance in the connection over time.  Soldering the crimped areas  cures the problem.  This could also happen on the power plug end as they are also crimped.   The glass fuse itself can go bad or become intermittent although it looks and tests good. Also the pins of the power connector on the radio or plug itself can be at fault.

ICOM 2100H

My beloved ICOM2100H 2 meter mobile went just over 5 khz off frequency on the receive. Transmit was fine. This turned out to be a simple fix. The 450 khz (NOT A 455 khz) resonator in the receiver IF had shifted frequency. It was a $2 part from Icom. Another time the microphone cord went bad. That was easily replaced with a new one as it plugs in on both ends.

Icom 706MKII

Found this at Dayton Hamvention one year. Got it for a song and the 500 hz CW filter was in it! After a few moments the display would not respond to the band up/down buttons properly. After subbing in the control panel from my 706MCKIIG and seeing the same symptoms, that ruled out the control panel. CI-V control did work so all was not lost for using the radio. A “used” main board from an Ebay vendor cured the problem. I theorize it was a main CPU problem.