Hacking in USB CAT control to the Kenwood TS-50

The Kenwood TS-50 was a great radio in its day and still holds its own against modern radios over 30 years later.

When Kenwood released this mobile 100W HF radio back in 1993, it was in the early days of modern computer aided transceiver or CAT evolution.  

This article explains how to add USB based CAT control to a vintage Kenwood TS-50 and maybe squeeze some extra life out of this great radio when it comes to digital modes.

Gathering Supplies

The bottom of the TS-50 has a small removable plastic disk that allows the user to access a 6 pin connector which the no longer available (and expensive) Kenwood IF-10D computer interface connected to along with the also expensive (and no longer available) Kenwood IF-232C serial converter.  

The original Kenwood IF-232C accessory permitted the inverted TTL communications native on the TS-50 to work via standard RS-232 serial communications at a blazing 4800 baud which is more than fine for simple communications between a radio and computer.

While there are some other aftermarket solutions still available in 2020, there is a cheaper way.

For less than $20 in parts, you can add modern CAT control to your TS-50 for easier use of digital communication modes like PSK31, FT-8, FT-4, JS8CALL and so much more. 

We will also not need to be removing that little plastic disk, so leave that alone.

To add modern USB CAT control to a Kenwood TS-50 you will need:

• CP2104 USB-TTL UART Serial Adapter
• JST ZH 1.5MM 6 Pin Female Single Connector with Flat Wires
• Some ingenuity to mount the CP2104 in your TS-50

Both items can be easily sourced via Amazon.com and you will even end up with 9 more sets of wires and matting PCB mount connectors that you can save for some other projects. Mounting inspiration is illustrated and detailed below.  

A small donation from the purchase link of either item is also headed to the Overlook Mountain Amateur Radio Club located in the Hudson Valley to help them maintain its famous 146.805 analog FM repeater and to add to its treasury for future additions like a DMR repeater or advanced APRS digipeater plus support great events like ARRL Field Day, Winter Field Day and other special outdoor events.

Connections on the TS-50

The below photo diagram illustrates which  of the six pins on the Kenwood TS-50 offers what function.

On the CP2104 USB-TTL UART serial adapter, we are going to need to attach the following wires.

For this to work, matching up the TX to the RX and RX to TX pins are needed between both devices.

While some other less detailed guides made it seem that only the TX, RX and GND pins were needed, on the recommended UART serial adapter, we also need to connect the 5V line for a total of 4 wires used. The remaining two wires from the 6 pin pigtail were just left for future use and taped up.

You will see the onboard green LED blink to show that communication is happening between the radio, TTL adapter and computer. You will not be able to see this LED since it will be hidden inside your radio if you install it the way that I did.

Mounting the CP2104 inside the TS-50

After removing all the outside case screws, go ahead and remove both covers of the TS-50.  You may wish to use a piece of painters tape to hold the TS-50 speaker in place while you flip the radio chassis over.

There are not many places to put the TTL adapter inside the Kenwood TS-50 unless you want wires hanging out of the TS-50 which looks messy and unsafe, so now is the time to get organized. If you wish to be neat with this modification, you will need to cut a hole into the side of your TS-50 on the side of the bottom cover.

The support bracket  for the TTL adapter was fashioned out of a brass corner bracket on hand and was insulated with a piece of heat shrink to ensure the metal to did not contact any PCB traces on the bottom of the TTL adapter.

Some zip ties were used to hold the TTL adapter in place, but another piece of heat shrink was used during final assembly to hold things in place. A screw and double nut were also used to attach the bracket to the radio for mechanical strength, but this is optional if you trust glue 100%.

Finally, some epoxy was used to fill up some small gaps left behind from cutting the TS-50 case so that the TTL adapter PCB can add additional structure to the finished modification.

To complete the assembly, simply route the connector end of the 6 pin wire between the front face and main chassis near where shown below.

You can then plug the connector into the radio and reassemble your radio carefully.

If cutting a hole in the side of the bottom cover of your radio, be sure to make sure your mounting bracket or the TTL adapter will not accidently squish board level components such as the picture toroid's.

Using the TS-50 CAT Upgrade

When using software like FLdigi, you can use the "hamlib" for control and select the TS-50 from the menu of supported radios. This is the easier path for CAT control. 

Be sure to set your speed to 4800 baud and you select the correct COM port. Most other settings should be automatically found when using FLdigi and most other software.

After you have the software configured, then go ahead and power up your radio after connecting the USB cable to the TS-50 and into the USB micro port. 

You should be easily be able to change frequency on the radio and have it track correctly in your software of choice. 

Using a TS-50 on digital modes with CAT control

Adding CAT control only offers control of frequency and some other basic functions of your TS-50.  This upgrade does not route any transmit or receive audio, nor does it offer PTT control.

It is possible to use the TTL adapter and a simple 4N26 optocoupler with the CTS wire to add on PTT, but its possible to accidently trigger transmit while the radio powers up or down when the USB wire is connected between the radio and computer, so this feature was left out of this article on purpose. If you wish to enable this convenience, that is up to you.

You can follow this article by HB9AMO  to add PTT if you wish and by using the extra wires we taped up before from the 6 pin connector.  

Routing of audio signals and PTT is done via the 8 pin microphone connector through your interface of choice such as a Rigblaster, Signalink or something like those devices.

 Summary

So now that we have near total control of the TS-50 using only two sets of wires, one for CAT and one for audio/PTT, the old Kenwood TS-50 is much easier to use for digital modes. 

It was decided that the Kenwood TS-50 was the perfect radio to use as part of an inexpensive dedicated digital data station for the Overlook Mountain Amateur Radio Club and joint HVDN special events. 

Given that the radio, computer, power supply, antenna tuner came from inventories held by both organizations, this was the perfect project to show how old and new can be used together to aid in digital awareness of amateur radio in the Hudson Valley and beyond.

If you enjoyed this radio, please support HVDN or OMARC with a small donation via the links below:

Support the Overlook Mountain Amateur Radio Club - 501.c3 charitable organization

Join Hudson Valley Digital Network as a supporting member

And, if you happen to be looking for a great portable case for your own go kit digital or otherwise, the Kenwood TS-50 along with its supporting cast of support components as a self contained digital station has a new home in this great 4U Gator Case and if purchased, a small donation also goes to the Overlook Mountain Amateur Radio Club too!  

You can see this in action at the upcoming COVID compliant Winter Field Day event at Ferncliff Forest in Rhinebeck between the hours of 2:00 PM to 6:00 PM Saturday January 30th and from 9:00 AM to 2:00 PM on Sunday January 31st 2021.