RTTY, Mac OS X Lion, PK-232 MBX, and CoolTerm …

Yes, I have an Intel Mac in the shack, which essentially means that I can run Windows on my Mac.  However, this is a less than desirable thing for me to do, as I’m sure is the case with most Mac owners.  The problem is — or was — that I couldn’t find a decent terminal program that could control my PK-232 MBX so I could operate RTTY or packet.

I had done various Google searches on the topic and didn’t come up with anything more than what I had already tried or known.  I tried ZTerm again, which generated unsatisfactory results, even with the correct  baud rate, data bits, parity and stop bits settings.  (The program author claims that ZTerm DOES run in Lion now).  I also tried the “screen” command in terminal, which generated the same results as ZTerm.

Out of determination, I did a Google search again a couple of days later and found “CoolTerm.”  I’m not exactly sure how I ran into it, but it sounded like it could be an option, so I looked into it.  This was EXACTLY the type of program I was looking for!  I had to download it and try it out.

Initial testing of CoolTerm showed that it was going to work perfectly with my TNC.  Setting it up is pretty straight-forward, and if you have any questions, the help file is a HUGE help!  The only problem I ran into was getting my TNC to accept a command, which was resolved by using an alternate command.  And yes, the program runs very well in Lion.

There are several nifty features to CoolTerm.  My favorite is the “send string” mode, which puts a command line interface at the bottom of the screen.  Commands are not actually sent to the screen until you press “ENTER.”  The same holds true when operating RTTY.  This probably wouldn’t work so well with RTTY, but would definitely be an asset if you were operating packet.

You can also open up a “send string window” which is a window separate from the terminal.  Type in your commands, hit ENTER, type your text, then press the SEND button or SHIFT-ENTER to send the text to the terminal.  This might come in handy if you’re going to call CQ on RTTY, but probably wouldn’t be much help  — if any — if you were to operate packet.

Another feature is the ability to save “default connection settings.”  Once you open the program, it will automatically load your desired default settings.  You also have the option of having the program automatically connect to the TNC upon startup.  You can also just save your connection settings if you have more than one modem.  I save my connection settings to the desktop so that I can just double-click on the file that has the settings for whichever TNC I decide to use.

Font size and type, font color, and background color are all customizable, which is a plus for me.

There are quite a few other features and options that the program has, but these are just a few of the ones I like the most.

The other awesome feature of this program:  It’s free, and can run on Windows, Mac, and Linux.  If you’d like to try the program for yourself, you can download it here.  Just scroll down to CoolTerm and click the appropriate link for your operating system.

The program will work with more than just the PK-232 MBX.  It will work with other TNCs or hardware that interfaces with the computer via a serial port … even if you use a Serial-to-USB adapter.

One last thing:  If you find the program useful, consider donating to the developer.  He doesn’t do this for a living, but I’m sure he still has to pay for website hosting, improvements to the program, et cetra.

73 de Andre


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  1. Dave WB7OBG says:

    What Serial-USB adapter do you use?

    • kc0mmy says:

      Hi Dave,

      My sincere apologies for not getting back to you sooner. Apparently the moderation settings on my site isn’t working properly.

      I use a couple of different USB-to-Serial devices. Get the ones based on the PL-2303 chipset as it’s cross-platform and very easy to install. Here’s a link to the one I purchased on Amazon.com:


      I’m not sure if it works with Windows 8 since I don’t have have a machine capable of running that OS. I DO know that it works on Windows XP and the latest version of Mac OS X just fine.

      The Keyspan USB-to-Serial adapters are by far the best. They’re very easy to configure. You’ll pay a bit more, but the price is worth the frustration … unless you’re up for a good challenge. Here’s a link to the keyspan, again off of amazon.com:


      I was actually able to successfully get the Keyspan to work using PlayOnMac (essentially a WINE emulator) to run a piece of software that could only run in Windows. I wasn’t so fortunate with the PL-2303 chipset.


  2. Rob says:

    Greetings to you Sir. I have used the excellent CoolTerm.exe for some 6 months now – mostly for testing data links. However, I need to obtain a version of CoolTerm.exe that is Windows 98 SE compliant – and have downloaded the v 1.2.0 from ” http://freeware.the-meiers.org/previous/ “. However, the opened/extracted file is always corrupted when I attempt to get it opened inside W98 SE. If you can, please see if you can successfully install the CooltermWin120.zip file. I find the interface so fine to work with in Vista and 7, and very much need a working version of CoolTerm.exe in Windows 98. Any help will be appreciated, as so far I have failed to find anything even close to it for 98.
    Thank you, Rob Enslin.

    • kc0mmy says:

      Hi Rob!

      Hmmm. Windows 98SE …
      I’m not sure if I’ve seen CoolTerm run on that. Honestly, I would try getting the latest version and seeing if that works. Here’s the link to my public Dropbox Account. It is for Windows and I was unable to unzip it, though it was on my Mac.


      What you’ll want to do as well is make sure that you UNZIP it to a folder on your hard drive. You might have to see if you can get a trial version of WinZip as I don’t think Windows 98 has a built-in unarchiver or program that can unzip files.

      If that DOESN’T work, go ahead and email me at webmaster@hamcomputing.org and I’ll share the folder with you that has the uncompressed files.

      I can’t guarantee that it’ll work, but we can give it a try.

      73 de Andre

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