Zero Retries Frequently Asked Questions

… About Data Communications in Amateur Radio

Updated 2023-02-24

Disclaimer - These are solely my opinions. I may be wrong, or poorly informed, but these are my best answers to Frequently Asked Questions (FAQs). Your mileage may vary, these answers may not be suitable to your particular situation.

As I begin this, I’ll largely confine this to operations in VHF / UHF. Eventually it will grow to encompass operations in HF (or perhaps that will be a separate FAQ).

Q. Should I invest the time and energy to get licensed as an Amateur Radio Operator? I can experiment with things like Wi-Fi, Bluetooth, LoRa, Iicense-exempt bands like 902-928 MHz, 2.4 GHz, 5.x GHz, etc.

A. Getting licensed as an Amateur Radio Operator is worth the trouble because it’s literally a license to experiment with radio technology. Amateur Radio Operators have access to a much greater range of spectrum, can operate at higher power levels, build their own radios, etc.

One primary downside to experimenting within Amateur Radio is that encryption is generally not allowed; if encryption is a big deal for your experimentation, then Amateur Radio isn’t a good choice.

One option for experimentation in Amateur Radio is to only receive radio signals. In the US, almost anything that’s transmitted in the electromagnetic spectrum is legal to receive. Software Defined Receivers (see below) allow you to receive almost anything.

Q. What’s wrong with using a Baofeng or other inexpensive handheld radio?

A1. In short, this class of radio has generally poor quality because its primary goal is to be inexpensive. A few issues I’ve heard reported are:

  • Some radio models don’t receive very well (low sensitivity) and can be easily overloaded by nearby strong signals (such as an FM broadcast station) (selectivity).

  • Some radio models (especially early units) were shown to “splatter” - transmit significant signals outside the intended frequency.

  • They’re frustrating to set up from the front panel.

A2. If you want to start off with a portable radio, here are some recommendations of not-too-expensive portable radios of good quality. For a starter radio, I recommend “FM only”; avoid digital voice radios such as D-Star (Icom), C4FM (Yaesu), or DMR (Digital Mobile Radio, various manufacturers). Prices are approximate as of 2023-02.

144-148 MHz (2 meters):

144-148 MHz (2 meter) / 440-450 MHz (70 centimeters)

144-148 MHz (2 meters) / 222-225 MHz (1.25 meters) / 440-450 MHz (70 centimeters)

  • Yaesu VX-6R - FM, 144-148 MHz / 222-225 MHz / 440-450 MHz, ~$250

The antennas included with portable radios such as the above are designed to be short and rugged; they are not particularly efficient. I recommend purchasing an antenna with better performance such as a Comet SMA-24. Note that the SMA-24 is a generic recommendation - purchase one for your particular radio’s frequencies and specific antenna connector.

This article updated 2023-02-24

Q. What is a Terminal Node Controller (TNC)?

A. (In progress)

Q. What is a modem / audio interface / sound card?

A. (In progress)

Q. For experimenting with data communications on Amateur Radio, should I use a TNC or a modem?

(In progress)

A. TNC is fixed function - will only work at 1200 bps (Audio Frequency Shift Keying [AFSK]… tones) or 9600 bps (Frequency Shift Keying.

A modem more flexible, but the software to operate with a modem is more complex than software to operate with a TNC.

Q. I’ve decided to use a TNC - recommendations?

  • (In progress)

  • KPC-3

  • TNC4

Q. I’ve decided to use a modem - recommendations?

  • (In progress)

  • Masters Communications

  • SignaLink USB

Q. What transceiver do you recommend to experiment with data communications in Amateur Radio?

A1. For “VHF / UHF dual band” - 144 - 148 MHz and 440 - 450 MHz, the Yaesu FTM-6000R is the only dual band Amateur Radio currently1 in production that incorporates a standard flat audio connector (requires the CT-164 adapter cable ). The cost is approximately $300 from Ham Radio Outlet.

A2. For 222-225 MHz, the Bridgecom BCM-220 is the only Amateur Radio currently in production that incorporates a (nonstandard) flat audio connector. The cost is approximately $350 from Bridgecom Systems.

There have been many Amateur Radios (now out of production, but sometimes available used) that have featured the standard flat audio connector. A list of Amateur Radios that have a dedicated Mini-DIN-6 data port is a good list maintained by Masters Communications.

Q. Can’t I just connect a TNC or modem to the microphone and speaker connections on a radio for data communications?

A. (In progress)

Q. This data jack / 1200 and 9600 / 6-pin MiniDIN connector / flat audio stuff is very confusing. Please explain.

This subject is confusing, so don’t be discouraged. There’s been a lot of (unintentional) confusion and conflation over the years.

Beginning in the 1980s, Japanese Amateur Radio manufacturers began including a “data jack” - Wikipedia article 9600 port.

(In progress)

Q. What are some good data communications modes to experiment with?

  • (In progress)

  • Packet Radio Automatic Packet Reporting System (APRS) on 144.39 MHz

  • Fast Light Digital (fldigi)


Q. What is the best Software Defined Receiver (SDRX)?

  • (In progress)

  • RTL-SDR (the original, genuine one)

  • SDRplay RSP1A (mostly VHF / UHF)

  • SDRplay RSPdx (HF / VHF / UHF)

Q. I’m a fan of free (as in beer) and open source software. What do you recommend?

  • Dire Wolf

  • Xastir

  • WSJT-X

  • fldigi

The End


At the time of this page was last revised.