Adventures in PSK31

Last weekend, I took my laptop to the Hands-On Museum, with the idea of perhaps trying to work some PSK 31. I’d downloaded and installed CocoaModem, a freeware package for the Mac, and I brought along the Buxcom Rascal interface that I purchased several months ago. I didn’t’ have a USB-RS232 adapter, but I guessed that I could buy one at the computer store downtown.

Not having a serial adapter proved not to be a problem, though. The only audio input on my iBook is the built-in microphone! So, unless I wanted to hold the speaker up to the microphone—or the computer up to the speaker—I wasn’t going to be operating any PSK31 anyway.

When I got home, I figured out what I needed to purchase. First of all, I needed the audio interface. The solution to this is the Griffin iMic. This device adds a stereo input and a stereo output to Macs that don’t have them.

I also still needed a USB-RS232 adapter. The folks on the Ham-Mac mailing list seemed to favor the Keyspan adapter.

I surfed around a bit for the best prices on these devices, and was able to snag both of them for $72, including shipping, from NewEgg. They arrived Wednesday, and yesterday I finally got around to playing with them. As you can imagine, when you get it all together, it’s a real jumble of wires:

Hooking up the audio input and output was easy enough, as was the RS-232 interface. I wanted to be careful about hooking up to my IC-746PRO’s accessory connector, though. The Rascal that I purchased supposedly came with a cable to connect it to that connector, but I couldn’t find any mention of the particular cable on the Buxcomm website. I finally resorted to buzzing it out.

When I was sure it had all the right connections, I plugged it in to the back of the rig. Then panicked. The moment I plugged it in, the rig went into transmit mode. Hastily unplugging it, I consulted the manual again.

The problem turned out to be the PTT configuration. CocoaModem uses a separate program to operate the PTT line. I dowloaded CocoaPTT, configured it, and marked that problem solved.

I spent the rest of the evening copying Latin American stations work Europeans on 7036 kHz. I could only hear the Latin Americans, though—HP1AVS in Panama, KP4ED in Puerto Rico, and a Venezuelan whose callsign I don’t remember.

This morning, I printed out the PSK portion of the CocoaModem user’s guide and read about how to adjust the transmitter. To do this, CocoaModem has a test tone function. The user guide says to adjust the audio output so that there’s just barely an indication on the ALC meter and then back off until it’s gone.

I don’t think the IC-746PRO works that way, though. Instead, you need to adjust the output level so that the ALC indicator stays within the brackets on the display. I did this, then set the output power to around 20W, and then tuned around for someone calling CQ.

I found KB3CVQ. Nervously, I answered his call. When he came back to me, I felt a little giddy. Not as giddy as I did when I made my first contact as a Novice, but along those lines.

I mentioned that this was my first PSK31 QSO and wasn’t sure I had things set up right. He replied that everything sounded just fine. We had a very nice QSO.

After lunch, I gave it another go. Not hearing anyone, I called CQ. After three calls, Marc, N4DR came back to me. Very cool. We had a nice QSO, lasting about a half hour.

I didn’t think that I’d like PSK31 so much, but there are some differences that I do like. For one thing, you don’t have to copy the QSO to actually have a copy of the other ham’s remarks. They are right there on the computer.

Another thing that I like is that you can start responding right away. By that I mean that you can reply to a comment while the other guy is making another comment. You just type it in to the transmit buffer, and it’s ready to go when it’s your turn to transmit. That’s pretty cool.

I’m not going to abandon CW and become a heavy-duty PSK op, but I don’t think, but it is fun, and I think I’ll be doing more of it in the future.


  1. Welcome to the world of PSK.

  2. As the sponsor for K5LBJ, the LBJ High School Amateur Radio Club in Austin, Texas, I have encouraged my students to get more involved in building and tinkering. This semester, we ran rather quickly through the Code (students made several CW contacts by themselves which made me quite proud) and Technician materials. As we finish up the General materials (using your manual, thank you), we are spending the last 4 weeks of the semester doing hands on.

    First, I had them breadboard the oscillator circuit featured in the ARRL “Big Project” pages. The kids enjoyed sending code using THEIR oscillator. Wiring the circuit using the schematic was also quite a thrill for many. They realized quite quickly that if they could wire this circuit, they could build anything with the proper schematic. Other students from earlier semesters have moved further. For example, I have a student that has worked off and on during lunch for about 6 months to build a digital modes (PSK31) interface for our Icom 706MIIg. He scrounged all the parts from our “boneyard” of donations and surplus electronics stuff that were being discarded. He finally finished getting the last connector soldered (tiny little boogers…) last week and plugged it in. Seems to work fine, but he is still testing it. The kids are proud of their handiwork and with regard to the digital interface are planning an EME contact. Digital modes are cool and add to the overall enjoyment of amateur radio.

    Congratulations on your new area of fun in the amateur community. Maybe we can work you with our new interface. ;)


    Ronny, KC5EES
    Austin, Texas

  3. Love your site. I did not know anyone did ham radio anymore. I come from an era when my friend had antenna wire strung from tree to tree outside of the farm house and talked to folks in Australia. We thought it was magic.

    That was, of course, also an era when a train went by your Mid West farmplace and you thought, Wow, they will be passing through the Rockies tomorrow!” There was a sense of adventure and possibility with both. Hope you folks still realize how magical what you are doing is.

  4. Dan KB6NU says:

    Thanks for reading and commenting, Jim. We do realize that it’s still magic–at least I do. That’s one big reason I write this blog.

    By the way, my 80m antenna is a wire strung between two trees in my backyard. I describe it on one of other pages here.

  5. Thanks for reading my comment. I write for a couple of folks here in Panama and commented in the Playa Community English Language news that I had seen a ham radio web site. I got a reply from a retiree who described connecting from off shore Africa to a guy in Miami to patched him through to his family in the States in the era BI, before internet.

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