GM Michael. A few added comments for your excellent list:

1) If you use a powered USB expansion hub, add a ferrite toroid on the cable coming from the USB power supply.
2C) Some hams will interpret what you wrote as an excuse to cut off the ground pin of the computer or monitor power cord. NO, NO, NEVER! Instead run a separate RF ground from the computer chassis to your station RF ground.
For a laptop use the retaining screw of a DB9 or DB25 connector shell, if your device still has them.
2D) Ethernet patch cables up through CAT6 are UTP, which stands for UNSHIELDED Twisted Pairs, four to be specific. There is NO separate shield conductor in the jacket, nor a metallic shield around the RJ45 connector itself.
Just use a ferrite toroid at each end.
2E) 24 VAC transformers can be RF-bypassed using .005 ufd caps from each output lead to safety ground. You can often use the cover plate mounting screw as your ground connection.
2F) The same approach as 2E also works for external speaker audio leads.
2H) Home laundry and HVAC systems. In general, newer high-efficiency models have more RF problems. Ferrite toroids INSIDE the appliance housing can work wonders if the wiring harness has connectors in the AC line input, OR an external noise filter for the AC line cord of a washing machine can reduce RF spurs by 25 dB or more. HVAC systems with variable speed blower control systems both cause RF noise and react badly to RF fields, but I have no experience troubleshooting them.
Add home solar power to your list of common offenders. Again, no experience here.

SignaLink) You can ground the metal box shell by simply wrapping an 18ga wire (or use a small crimped ring or spade terminal) under the head of any of the screws holding the rear panel, then connect to your station RF ground.
The case is isolated from both USB and analog audio signal grounds, so this does not affect use of the USB shield isolators.. This one made a BIG difference in my shack!

DC power supply) This applies to both linear and switching designs. READ THE PS MANUAL FIRST! This step may void some manufacturers' warranty and UL/CSA approvals.
Remove any jumpers between the DC negative output lead and PS chassis or line cord ground Add a .005 ufd cap from each DC output lead to chassis ground if not already there.
NOTE: Samlex DC outputs are already isolated and bypassed, but many others, including Astron, may randomly have the negative side grounded and no RF bypassing.
--
Karl  WA8NVW  OH
WA8NVW@...
in WSJTX@... supply units

Robert, You will need two interfaces, one for the CI-V CAT control
and another for the Audio I/O.
This one for the CI-V CAT control,
https://www.g4zlp.co.uk/unified/IcomCAT.shtml
This one for the Audio I/O,
https://www.g4zlp.co.uk/unified/DM_MiniPro_SC.htm click on the Soundcard
tab to see a config for HRD.
This cable for the Audio I/O interface,
https://www.g4zlp.co.uk/unified/DMleads.shtml ICL02 for your IC756P3
The CI-V CAT control is for frequency changes from WSJT-X and PTT keying
and to put it into USB-D mode.

Bruce N7XGR

Thanks, guys, for all answers.



Another (stupid?) question: will these cables also work for connecting the transceiver to Ham Radio Deluxe?



73 Robert, OE7OER





Von: Bruce <n7xgr1@...>
Gesendet: Donnerstag, 18. August 2022 01:45
An: main@wsjtx.groups.io; oe7oer@...
Betreff: Re: [WSJTX] CAT control for Icom IC-756 Pro III #Cat_RigControl



Robert, Right here, https://www.g4zlp.co.uk/unified/IcomCAT.shtml



Bruce N7XGR

... and still another location for interfaces.   This one also sells an
'all-in-one' cable with CAT (C-IV), and built in Sound Card.

http://xggcomms.com/Icom-Interface-Shop(2066628).html

Neil, KN3ILZ

This one should work though there are some recommendations to add chokes to it.  If you get cat errors while transmitting would mean you need to work on RFI in the shack and possibly add chokes to the cable.
https://www.amazon.com/BQLZR-Cable-IC-275-IC-756Pro-Shortwave/dp/B00IM9HVBW

My ever-expanding list of RFI recommendations
RFI Problems
TestsIf problems are occurring only during transmit: #1 Reduce power to zero and see if the problem stops -- if it does stop than it is definitely RFI.  You will see certain higher power levels on certain bands that cause problems. Then, if problems are occurring during non-transmit periods it indicates a system problem with USB devices so... #1 Check USB Power Management option is turned off on all USB devices Device Manager for Windows. For Linux set autosuspend=-1 https://docs.kernel.org/driver-api/usb/power-management.html
RFI Fixes: #1 Free - Move USB cables to another port -- some ports are more susceptible than others. #2 Free -- Check your grounding system.  rod-outside-the-shack is a common problem when it's not bonded to the main house ground.  Common grounding mistakes: A. Ground rod outside the shack that is not bonded to the main house ground. B. Shack equipment bonded incorrectly (e.g. daisy chained instead of common ground point) C. Desktop computer grounded to the house ground instead of the shack ground. D. Ethernet cables that bring RFI into the computer...which then ends up going to the rig too since the ethernet shield is tied to the case which is tied to USB shield which is tied to pin 4 on the USB cable (a very common problem on most all USB devices -- see my QRZ page). E. Wall warts -- 24VAC supplies in sprinkler and alarm systems are notorious for picking up RFI into your electrical system. F. Speaker wires G. Lamps (yes...lamps around the house have unshielded wires as do many other appliances). H. Washer/Dryers are notorious for generating and picking up RFI.  
B through G may all need chokes. http://www.k9yc.com/GroundingAndAudio.pdf  #3 Free -- start unplugging devices around the house and see if there's one device that is acting as a bad source of RFI.  This presupposes you can easily repeat the problem on your rig setup. #4 Cheap -- Add some USB shield isolators (see my QRZ page).  I use one on my SignaLink for example. #5 Minimal $$ -- Good USB cables like this https://www.amazon.ca/Tripp-U023-006-Device-Ferrite-Chokes/dp/B003MQ29B2/ref=sr_1_5?crid=11YRNPWDVWGCU&keywords=usb+cable+with+choke&qid=1658187349&sprefix=usb+cable+with+choke%2Caps%2C139&sr=8-5 #6 Maybe free (if you have chokes...otherwise can get a bit costly) -- add chokes to USB cables first, then all other cables including power, ethernet, and control cables. Fair-Rite torroids are good quality -- do NOT buy cheap Chinese ones --  https://www.fair-rite.com/product/toroids-5943003801/  You can use clip-ons but torroids allow multiple wraps and give better results. https://www.fair-rite.com/product/round-cable-snap-its-431176451/ I couldn't find type 31 torroids at Fair-Rite as of 20220721 but Palomar has some palomar-engineers.com/ferrite-products/ferrite-cores/ferrite-ring-toroid-combo-pack/ Newark also carries them https://newark.com/c/passive-components/emc-rfi-suppression/ferrites-ferrite-assortments?brand=fair-rite

Mike W9MDB

Hi Robert
I use RT Systems cable. On my IC756 ProIII and IC7600
https://www.rtsystemsinc.com/HF_c_32.html
I tried a cheap one on E-Bay did not work.

--
Jim Sherwood, *N4UOZ

Robert, Right here, https://www.g4zlp.co.uk/unified/IcomCAT.shtml

Bruce N7XGR

Sorry if this has been addressed before, I recently bought a used Icom IC-756 Pro III.
How do I connect this radio to a Win11 PC?
What CAT interface do I need and where can I get it?

vy 73 de Robert, OE7OER