Tuesday, February 14, 2017


I know you might be tired of seeing posts about the Easy Digi interfaces I've been playing around with. But, I promise this one is the best iteration so far. I was recently contacted by another ham who wanted a cheaper alternative to a Signalink USB, while keeping the plug and play ease of use. This is what I came up with.

The Easy Digi boards are a great kit for those who want an easy project. I've done a couple other posts about them and if you want more details click here and here.

1st Easy Digi Interface
The last kit I assembled was with the goal of making it as compact and modular as I could. I believe I succeeded, however you are still going to need a serial port (either a good old fashioned COM port or a USB/Serial adapter) and a sound card (the one already in your computer or a USB version). So even though the interface itself is very small, you still need a few peripherals and cables to make it work.

This time the goal is simplicity. I needed to create an interface that has one USB connection to the PC and a modular plug for connecting to a transceiver. That means I have to cram all the components into a box and try to keep it compact enough you can easily throw it into your go bag.

You need three major components to make this interface work. You need the Easy Digi circuit, a serial device to trigger the PTT, and a sound device. Fortunately today all of these components are relatively cheap and easy to get.

For this project I picked up (Total $38.83) :
  • Easy Digi Interface Kit ($12.55)
  • USB to DB9 Serial module ($5.95)
  • USB Sound Card ($5.28)
  • 4 Port USB Hub ($1.98)
  • CAT5e RJ45 M/F Panel Mount ($5.95)
  • ABS Plastic Project Box 3.5 x 3.5 x 2.24 inch ($7.12)

Easy Digi Assembled
The first step is to put the Easy Digi kit together. I won't go into detail for that here, the instructions with the kit are very easy to follow. 
USB Serial Device
USB Serial Device without case

USB Serial Device with DB9 removed

After that I started taking plastic cases off all the stuff I ordered so everything would fit in the project box. Luckly the enclosures were all just fitted together and not glued, so they just pulled apart. 
USB Hub without Enclosure

USB Sound Device

USB Sound Device with case removed
I decided to wire the USB sound card directly to the Easy Digi. So, I pulled out the solder sucker once more and got the 3.5 mm jacks off the sound card. This left nice through hole soldering connections for the wires to run to the Easy Digi.

USB Sound Device and Serial Adapter wired to Easy Digi Board
Next I needed to attach the USB serial device that controls the PTT circuit. There needs to be a connection from the DTR, RTS, and ground pins on the serial device to the corresponding solder pads on the EasyDigi board. Note that when looking for a USB serial device, you need one that presents the correct voltages. I've found that usually the adapters that actually have a DB9 connector on them provide the 5+ volts necessary to operate the optocoupler for the PTT. Don't bother trying to use the cheap UART devices.
RJ45 Panel Mount
RJ45 Panel Mount wires exposed
RJ45 Panel Mount wired to Easy Digi
After that, I needed to install the RJ45 panel mount that will connect the device to the radio. I chopped the plug end of the panel mount cable off and wired it to the board using the following pinout. This assumes the panel mount is wired as a T-568B standard, starting with the orange/white, orange wires. 

PIN  Color                  Function
1      Orange/White     RX Audio
2      Orange                RX Audio
3      Green/White       MIC In
4      Blue                    MIC Ground
5      Blue/White         PTT High
6      Green                  PTT Ground
7      Brown/White      Not Connected
8      Brown                 Not Connected

Windows Installing New Devices
Now that is all connected, it's time to plug it in for testing! It does take a few minutes for Windows to install the three USB devices and it may ask for a reboot. 

Device Manager showing new devices
Install Old Prolific Driver if needed.
You can look at the device manager and see the new devices installed. It should have installed a new PnP USB sound device, a new COM port, and the USB Hub. Hopefully Windows found all the drivers automatically. If not, there will be an error symbol next to the device in the list. If that happens, it's most likely a driver issue and you may need to install a driver manually. The USB serial interface I found had a fake prolific chipset on board, so I had to install the old driver version found here.
UZ7HO SoundModem Settings
Winlink Express Settings
Running the UZ7HO soundmodem software and Winlink Express, I test my connection using the interface. Once I'm sure the components are working correctly, I installed them in the project box.  
Inside a finished Super Easy Digi
To install the components in the box, I used double sided foam tape. This stuff does a good job of holding the components to the project box without drilling or screws. All the components fit nicely in the project box with a little room to spare. 

To route the cables out of the box. I used a rotary tool to cut a notch in two of the sides of the box. One for the USB hub cable to come out and one for the RJ45 jack. Luckily the USB hub cable has a molded strain relief still attached and I was able to reuse it with the box. The RJ45 jack is held in place by the lip of the enclosure. It pinches the cable enough that it takes quite a lot of force to either pull it out or push it into the box. 

Complete Super Easy Digi
As you see, the completed project is still a fairly small size and is very convenient to use. Not only will this interface work for getting on packet radio, you can utilize it with any of the sound card digital modes as well.

I hope you enjoyed this project! 73


  1. Is the Easy Digi necessary in all cases? I'm trying to get into digital on my Yaesu 450D. I installed Fldigi on a Raspberry Pi and want to interface that with the Yaesu. Someone told me this can be done with two cables and a sound card dongle and others have suggested the Easy Digi but I just don't know if it's needed. I do appreciate your wiring write-up..it's the only one I have found so far.

    1. You don't need one in every case. It's primarily for isolation between the rig and computer. With my rigs, I've noticed issues when just running cables. For example, my HF rig would keep getting interference. When I experimented with using only audio cables, it did work, it would just sometimes transmit a dirty signal.
      Another example is using HT's and mobile rigs. If you try to simply use cables with many HT's or mobile rigs, the wires short to ground when plugging them into the computer's sound card and the radio will get stuck in transmit. The transformers installed on the EasyDigi gives the electrical isolation to prevent this and make things work smoothly.

  2. Thanks for your tutorials! From your YouTube tutorial on WinLink and EasyDigi, I don't see how to get WinLink to use the software TNC. When selecting Open Session, the popup asks for which TNC you're using, and our software TNC isn't in the list. Did I miss an important part of the setup?

    1. I will answer my own question: to use WinLink with a softmodem, set it to KISS mode. I should have been able to guess that, but there you go.

    2. Thanks for visiting the blog Dylan! Glad you figured it out. You are correct that it needs to be setup as a kiss type tnc inside of Winlink Express.

  3. Thanks Josh for this detailed write up. Would it be possible to include part numbers for the various parts ? And what radio are you using this with. Will this work on HF too. The picture you show and list as a "Sound Device" I am particularly interested in. Bill AF7ZA

    1. Hey Bill, thanks for visiting the site. Part numbers might be a little hard to come by since I sourced most everything from eBay and it was all generic and made in China. The sound device is a generic USB sound card. They are really cheap, only a few dollars. It will add an extra sound card to your computer to use specifically for this interface. Your best bet on finding the components will be to search the name of each on eBay or Amazon.

      I'm using this interface with many different radios including HF. I have tested it with a Baofeng UV-5r, Kenwood TM-281, Yaesu 1900, and a Yaesu FT-840.

      I've had lots of success with digital modes on HF as well as using this for packet operation on VHF. This is the only interface I have used for the past couple years.

  4. How did u wire the 3.5 cables? what is the pinout for connecting to the easy digi?

    please contact me - KG7QEO

    1. The 3.5mm connectors are wired as follows.
      Tip/Ring -> Audio
      Shield -> Ground
      This article has a little more detail on wiring up the audio connections.

  5. Josh: Do you use a standard ethernet between the microphone port on the radio and the panel mount connector on the Easy Digi Box? Is there some sort of adapter for RJ-45 to to the 3.5mm inputs that the Baofeng radios use?

    1. The side that is connected to the EasDigi is a standard RJ45, the other end is custom to what ever rig needs to be connected. In the case of the UV-5r, it requires a 3.5mm and 2.5mm plug for the speaker and mic jack. I didn't have any 2.5mm plugs handy, so I found a 3.5mm to 2.5mm adapter for connecting to the speaker connection.
      Here's a link to another post I did where I show some more details in cable construction.

  6. cool idea, i wanted to replace the netowrk cable with a fm traciever.. like a car radio fm trasmitter