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ICOM 705 mounted in my Rover Set up left of the FT991A as the IF radio for microwave.
ICOM 705 Upgrade USB-C/SEND control board
AA2SD/R Sept VHF Preparation August 6, 2026 - Based on the recommendation from fellow Pack Rat Tom K3GM, I decided to attempt this project myself, as the micro USB port was getting very shop worn, from my multiple rover installations. This would also benefit the radio with additional protection for connecting to amplifiers. I only use the ICOM 705 for an IF Rig with my transvertors while mobile.
Installing an upgraded USB-C/SEND control board (such as the popular replacement unit from iHelpU.tech on your Icom IC-705 replaces the fragile micro-USB port and fixes vulnerable amplifier send line circuits. The simple drop-in hardware installation takes about 15 minutes using a standard Phillips screwdriver .
This upgrade changes the ICOM 705 connector from a micro USB to USB C connector
At the time of this installation I paid $63.99 for the board, and waited about 4 weeks as this popular item was on back order. I noticed several Chinese boards at lower prices, but after discussing this with Tom I decided to go with the board produced by Ben, he offered a step by step well documented installation guide, and a video to follow at: https://www.ihelpu.tech/shop/ihelpu-705-usbc-icom-ic-705-usb-c-send-control-board-upgrade-20
This is a drop-in replacement control board (Connect Unit B-9128B) for the Icom IC-705 radio. Designed by Ben (KD9LJF), it is an easy upgrade for any IC-705 radio.
Comments from Ben KD9LJF Below: visit this site at https://www.ihelpu.tech/icom-705-usbcsend-install-guide
Icom 705 USB-C/SEND Board Installation Guide
USB-C The upgraded control board has a USB-C port that retains all of the original port's functionality (including computer data). This port is just a connector swap and works identically to the original board. This means that it does not add any USB-C Power Delivery (PD) features. You can still charge the radio through the USB connector with any USB-C charger, but it will still only charge at 5V and around 7.5W from the charger with the radio turned off.
USB-C The upgraded control board has a USB-C port that retains all of the original port's functionality (including computer data). This port is just a connector swap and works identically to the original board. This means that it does not add any USB-C Power Delivery (PD) features. You can still charge the radio through the USB connector with any USB-C charger, but it will still only charge at 5V and around 7.5W from the charger with the radio turned off.
SEND line The SEND/ALC circuit has also been upgraded for additional protection for connecting external amplifiers. The original board from Icom was only capable of switching less than 30mA of current on the SEND line. Connecting an amplifier that operates by switching 12V to ground would likely fry your original board as it did for mine. Our new control board has upgraded MOSFETs for the SEND line that can switch up to 1.0 amp of current. We also added a Zener diode to protect against voltage spikes above 16V. Our upgrade to this circuit makes your 705 compatible with most 12V amplifiers without additional adapters other than the TRS 3.5mm cable.
SEND line The SEND/ALC circuit has also been upgraded for additional protection for connecting external amplifiers. The original board from Icom was only capable of switching less than 30mA of current on the SEND line. Connecting an amplifier that operates by switching 12V to ground would likely fry your original board as it did for mine. Our new control board has upgraded MOSFETs for the SEND line that can switch up to 1.0 amp of current. We also added a Zener diode to protect against voltage spikes above 16V. Our upgrade to this circuit makes your 705 compatible with most 12V amplifiers without additional adapters other than the TRS 3.5mm cable.
https://www.ihelpu.tech/icom-705-usbcsend-install-guide
I was able to complete this project in less than 20 minutes, and now have amp protection and an upgraded connector for mobile use, thanks to Tom for sharing this heads up for the ICOM 705.
Go Out and Play Radio Listen for the Weak Ones
Scott AA2SD/R www.aa2sd.com
609 254 7120 Pack Rat DMR 8804
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