In 2003 I was writing a column, "QRP Community", for the ARRL Website. My April column was entitled "The Odyssey of the Argonauts"( https://docs.google.com/document/d/1VfIO1v2O2iDNJAoi9i83r6phBCAXG2zS1h0udyK5WLQ/preview). The article described the 1970s origins and later versions of the TenTec Argonaut series. This weekend I extended my own personal odyssey with Argonauts as I made FT4 and FT8 contacts with one of my 1970s vintage TenTec Argonauts, a model 509.

After a few minutes of soldering to build interface cables from an MFJ 1204 USB Radio Interface, a few minutes of WSJT-X software set up and Windows Sound Devices configuration and renaming and a few hours of troubleshooting (more on that later), my first call resulted in an FT4 QSO. Quickly in the next few minutes, I added another half-dozen FT4 QSOs with the Argonauts mighty 2 watts!

You might be asking why would I want to use a forty-year-old radio with no computer interface capability for a computerized digital mode like FT4 or FT8? Well, partly it was the challenge to see if I could do it and secondly my continued fondness for the Argonaut series that I lusted after as a teenager interested in ham radio.

So how did I do it? First, you need to realize that you really do not need computer control of the radio's frequency as you can set the dial manually. Next, I need a way to interface the computer's audio input/output from WSJT-X to the radio and a way to control PTT to key the radio. I had just acquired a used MFJ 1204 USB Radio Interface with no pre-made radio-specific-interface cable so I was going to have to make up a cable anyway so Argonaut became my target. A quick check of the owner manual gave me wiring for Argonauts Microphone plug and mono speaker jack. One half of an old RJ-45 network cable provided the end to plug into MFJ-1204. I used a small project box and scrap of circuit board prototyping board to complete the project.

After I completed soldering and hooked everything up I connected the interface to radio and computer. Connecting the USB cable from the MFJ 1204 to computer resulted in two new sound devices on Windows 10. Unfortunately, they gave them the same names as the USB sound devices from my Elecraft K3S, so I renamed each with "MFJ" to distinguish them. I cloned my WSJT-X configuration and then made configuration changes for the Argonaut. See settings below. Never mind that the Argonaut does not have VOX, the MFJ 1204 will take care of keying the rig (after you make the adjustment I made below).

I tuned the Argonaut to 14.070 USB and began to hear FT8 signals. I ended up adjusting frequency to approximately 14.073 (remember the dial is not that accurate on this analog display anyway) to get signals in the passband. I was almost immediately rewarded with decoded stations on the WSJT-X display. FT8 was very busy so I dialed up to 14.080 and changed to FT4. After receiving stations I tried transmitting but the radio did not respond. PTT was not working. I recheck all of my connections, soldering , etc. still no luck. After an hour I gave up and asked on the WSJT-X mailing list if anyone knew how to solve my PTT issue. Fortunately, the 2nd reply gave me the clue to solving my problem. Mike Black, W9MDB reminded me that there has to be enough audio coming out of your computer to trigger the PTT circuitry in the MFJ-1204. A quick adjustment of my Windows sound level settings solved the problem and my first 2-way FT4 contact with K7GA using the Argonaut was logged in minutes. The best thing is this simple setup will work with almost any radio with SSB capability, no matter its age.