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Digital Mode Troubleshooting Guide
Fix CAT control, PTT, FT8, WSJT-X and digital mode audio problems on Icom, Yaesu, Kenwood and Xiegu radios.
Whether you're struggling to get CAT control working, seeing no activity on the WSJT-X waterfall, unable to key your radio into transmit, or getting little to no output power on FT8, you're not alone. These are some of the most common issues encountered when setting up digital mode software and interfaces.
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We've been designing and supplying CAT control and digital mode interfaces to amateur radio operators for over 20 years. During that time we've helped customers resolve everything from simple connection mistakes and grounding issues through to obscure radio menu settings, software conflicts and the occasional problem that leaves us scratching our heads too.
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This guide brings together the most common issues and solutions we've encountered over the years. Before diving into software settings, COM ports and radio menus, we'll start with the hardware and
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Follow the sections below to diagnose CAT control, PTT, audio, timing, grounding and radio setup problems, with tips covering popular transceivers from Icom, Yaesu, Kenwood and Xiegu.
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Whether you're setting up your first FT8 station or chasing down a stubborn fault in a well-established shack, we hope this guide helps you get back on the air quickly.
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On This Page
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Let's Start With Station Grounding (Important)
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Let's carry our basic checks on the hardware
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Let's Start With Station Grounding (The cause of many issues!)
Treat Your PC As Part Of The Station
Poor station grounding is one of the most common causes of CAT control, audio and interference problems when connecting a computer to your radio.
Ideally, all equipment in the shack should be connected to a common grounding point, including the transceiver, power supply, amplifier and computer. Many operators carefully ground their radio equipment but overlook the PC, forgetting that once a CAT or Digimode interface is connected, the computer becomes part of the station.
Our interfaces sit between the radio and the computer, and a poorly grounded PC can introduce RF pickup, ground loop issues and unwanted noise into the system. In some cases, the interface can become the unintended path between the station ground and the computer.
Although the audio and Opto-PTT circuits in our USB Digimode interfaces are galvanically isolated, the CAT connection is not, so good grounding practices remain important.
Desktop PCs and Laptops
Desktop PCs are usually straightforward to ground because their metal chassis is normally connected to mains earth via the power supply. In many cases, a simple connection from the PC chassis to the station ground bar is all that is required.
Laptops can be more challenging. Most use double-insulated power supplies with no direct earth connection, which can allow small leakage currents and RF pickup to find their way into the station. On one of our test laptops we measured around 45V AC between the laptop power supply output and station ground. While this is at very low current, it can still contribute to unwanted noise and interference and was the cause of the occasional annoying tingle!!
Grounding a Laptop
One simple solution is to use a USB grounding lead connected between a spare USB port and the station grounding system. These are readily available online or can easily be made from a spare USB cable.
When making your own, connect only to the USB screen and 0V connection. Never connect to the USB data lines or the +5V supply.
If you can include both your radio equipment and your computer in the same station grounding system, you will often eliminate problems before they have a chance to appear.
For a more detailed discussion of station grounding, we recommend reading our dedicated Station Grounding Guide.
Check out our Ham Shack Grounding Guide here
Let's carry out basic checks on the hardware
​One of the most common mistakes when setting up a digital mode station is to assume the problem lies with WSJT-X, FLDIGI, radio menu settings or USB drivers.
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In reality, many CAT control, PTT and audio problems can be traced back to the physical installation of the station. Before changing software or radio settings, spend a few minutes checking the hardware side of the setup.
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A digital mode station is a complete system consisting of:
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Your transceiver
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Your PC or laptop
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The interface
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The connecting cables
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The station grounding system
If any part of that system is not connected correctly, the symptoms can often appear to be software related when they are not.
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Check All Connections
It sounds obvious, but start by checking the USB, CAT and Data/Accessory connections between your PC, interface and radio. A surprisingly large number of setup issues are caused by connectors not being fully inserted or being connected to the wrong socket.
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Many radios have multiple ports that appear similar but perform completely different functions. For example, one of the most common setup issues we see with the Xiegu G90 is customers connecting the CAT lead to the rear-panel port marked COM. Despite the name, this is not the CAT control port. Always refer to the radio manual and ensure the CAT and Data connections are plugged into the correct sockets.
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If you are experiencing problems with CAT control, PTT operation or transmit/receive audio, disconnect the leads from the radio and carefully inspect both the plugs and sockets. Look for bent pins, damaged connectors or anything that appears out of alignment.
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Over the years we have also encountered faults within customer radios themselves, including intermittent accessory sockets and poor internal connections. While these cases are less common, they can produce symptoms that closely resemble a faulty interface or software configuration.
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Some older Kenwood radios can present an additional challenge. Although they use a 13-pin DIN accessory connector, the socket dimensions do not always perfectly match modern DIN plugs. This can make insertion feel unusually tight and occasionally requires a little care and patience to ensure the connector is fully seated.
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Important: Multi-pin connectors should never require force. If a plug does not appear to fit correctly, stop and check the orientation before proceeding. Attempting to force a connector into the wrong socket is one of the most common causes of bent pins that we encounter during support enquiries.
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