W4HM's ICOM IC-756 PRO 3/2 IC-746 PRO DIGITAL MODES INTERFACE INFORMATION
 

 

 


The following information is also applicable to the Icom IC-756 Pro II and III.

If you want to interface the IC-746 Pro or any other Icom rig with a computer for rig control, an outboard CI-V CAT device is required. As follows is some information on hooking up the IC-746 Pro 8 pin DIN jack to the MixW Rig Expert Tiny 5 pin DIN plug CI-V CAT interface.

The connections are as follows:

Icom IC-746 Pro digital mode connections to ACC(1) jack/8 pin DIN plug.

#Pin #4- Sound card modulated audio out to mic in on transmit.

*Pin #5- Rig receive audio out to sound card in for speakers.

@Pin #3- PTT.

!Pin #2- Ground.

Bux Comm 8 pin pre wired part #DIN CBL-8D plug.

#Red wire from Rig Expert Tiny interface to yellow wire on Bux Comm 8 pin DIN prewired cable, for sound card modulated audio out to rig mic in on transmit .ACC(1) jack pin #4.

Note!!! I had to much signal into the rig mic on transmit, so I had to place a variable resistor in series before I was able to reduce the modulation to an acceptable level so as to see no ALC action and a clean signal with no extra side bands.

*White wire from Rig Expert Tiny interface to green wire on Bux Comm 8 pin DIN prewired cable, for rig receive audio out to Sound card in. ACC(1) jack pin #5.

@Yellow wire from Rig Expert Tiny rig interface to orange wire on Bux Comm 8 pin DIN prewired cable, for rig PTT. ACC(1) jack pin # 3.

!Ground braids from above three wires from Rig Expert Tiny interface to red wire on Bux Comm 8 pin DIN prewired cable, for rig ground. ACC(1) jack pin # 2.

Creative Sound Blaster Digital 4.1 sound card jack connections.

Blue Jack- Audio in. (Not used).

*Red Jack- Rig RX audio out to sound card audio in for speakers.

#Green Jack- Sound card modulated audio out to rig mic in for TX output.

Black Jack- Sound card out for duplex speakers. (Not used).

NOTE!!! I have no financial interest in the following products. I'm merely a very satisfied customer.

I highly recommend the MixW Rig Expert Tiny as a digital interface as far as quality of parts and construction and of course operation . It includes the CI-V circuitry necessary for computer control of Icom rig's including frequency. You can learn more about this interface at:

MIX W RIG EXPERT SITE

I also highly recommend the MixW multimode digital software. You can learn more about it at:

MIX W SOFTWARE SITE

For more general information on the Icom CI-V CAT interface check out the following website:

DF4OR ICOM CI-V INTERFACE SITE

As far as digital modes operation such as PSK31 here is how I set up my IC-746 up for a clean output signal:

I use the 8 pin DIN jack on the back of the IC-746 Pro to my MixW Rig Expert digital interface. This gives me a fixed amount of output that drives the
interface and MixW software very easily.

As far as settings, it's not necessary to turn the MIC GAIN potentiometer down to zero and the COMP RF speech compressor off, because the attached microphone will not pick up audio and inject it onto your digital signal when you the D-USB mode, as it does on the IC-718.

I do turn off all XP OS sounds as they will be transmitted. I set my RF PWR control all the way to the right (clockwise) which gives me ~100 watts output. I control transmitted audio level output with the Creative Sound Blaster Digital 4.1 sound card Volume Control and Wave sliders.

Doing it this way assures the cleanest audio without IMD distortion. I can run up to 100 watts output on PSK31 with no ALC meter action and get -30 or better IMD reports. I usually run no more than 25 watts output on PSK31 and mostly 5 watts as I'm into QRP.

One last important note. It is common accepted procedure to have no ALC meter action on transmit to assure a clean signal but with the IC-746 Pro you can run the ALC meter action up approximately 25% and still put out a clean signal.

 

You can contact me
Thomas F. Giella W4HM
in Lakeland, FL, USA at

thomasfgiella at gmail dot com

 

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