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A Comprehensive Guide to Radio Teletype (RTTY) for Ham Radio Operators
Foreword
In the ever-evolving world of amateur radio, where digital modes like FT8 and JS8Call dominate the airwaves, there's something timeless and exhilarating about diving back into Radio Teletype (RTTY). For new operators just earning their licenses and discovering the thrill of HF communications, RTTY offers a straightforward yet rewarding way to connect with fellow hams across the globe, exchanging messages in real-time without the need for voice. It's a mode that hones your skills in tuning, signal decoding, and contesting, building a foundation that enhances your overall radio proficiency.
For seasoned operators who've chased DX on CW or SSB for decades, revisiting or rediscovering RTTY can reignite that spark of innovation from ham radio's golden era. This mode, with its mechanical roots and digital simplicity, bridges the analog past and the software-driven present. It encourages experimentation with interfaces, software tweaks, and antenna optimizations, reminding us why we fell in love with the hobby in the first place. Whether you're participating in a high-stakes contest or casually ragchewing, RTTY fosters a sense of community and achievement that's hard to match.
I encourage all operators—newbies and old-timers alike—to give RTTY a try. Set up your station, fire up the software, and join the chorus of tones on the bands. You'll find it's not just about transmitting text; it's about preserving a piece of ham radio history while pushing your setup to new limits. For more resources and personal insights, visit my website at https://www.n4ywd.com.
7 3, N4YWD
Chapter 1: Introduction to RTTY
Radio Teletype (RTTY) is one of the oldest digital modes in amateur radio, allowing operators to send and receive text messages over radio frequencies using frequency-shift keying (FSK). Unlike voice modes such as SSB, RTTY encodes text into audio tones that are transmitted via your radio, decoded on the receiving end by software or hardware. It's particularly popular on HF bands, where it excels in contests and DX chasing due to its robustness in noisy conditions.
RTTY operates primarily using the 5-bit Baudot code, which limits it to uppercase letters, numbers, and basic punctuation. This simplicity makes it accessible for beginners while providing a challenge for optimization in weak-signal environments. Standard parameters include a baud rate of 45.45 baud and a frequency shift of 170 Hz, though variations exist. Common frequencies are found in the digital sub-bands: for example, 3.580-3.600 MHz on 80m, 7.080-7.100 MHz on 40m, 14.080-14.100 MHz on 20m, and similar segments on higher bands.
Why choose RTTY? It's contest-friendly, with events like the ARRL RTTY Roundup and CQ WW RTTY attracting thousands of participants. It also requires minimal power—often 50-100W suffices for global contacts—and integrates well with modern software for automated decoding.
Chapter 2: The History of RTTY in Amateur Radio
RTTY's roots trace back to the 19th century with Émile Baudot's invention of the Baudot code in 1874, initially for wired telegraphy. By the early 20th century, it evolved into radioteletype for wireless use, with commercial and military applications during World Wars I and II. Post-WWII, surplus teletype machines flooded the market, enabling hams to experiment with RTTY.
Amateur adoption surged in the 1950s, with publications like RTTY magazine (1953-1966) promoting the mode. Early setups used mechanical teleprinters like the Model 15 or 28, connected via TU (Terminal Unit) for FSK modulation. By the 1970s, microprocessors allowed software-based decoding, transitioning from clunky machines to computers.
The 1980s saw RTTY contests boom, with standardization on 45.45 baud and 170 Hz shift. Today, while newer modes like PSK31 have emerged, RTTY remains a staple for its reliability in poor propagation, with ongoing innovations in software integration.
Chapter 3: RTTY Basics and Technical Parameters
To operate RTTY, understand its core elements:
Baud Rate and Code: Standard ham RTTY uses 45.45 baud with Baudot code. Faster rates like 50 or 75 baud are rare but used in contests. Each character is 5 bits plus start/stop bits, totaling 7.42 bits per character.
Frequency Shift: 170 Hz is standard on HF, with mark (higher frequency) and space (lower). Some setups use 200 Hz, but 170 Hz ensures compatibility.
Modulation Types: FSK (Frequency Shift Keying) for direct radio control, or AFSK (Audio Frequency Shift Keying) via sound card. FSK is cleaner but requires radio support.
Polarity and Sideband: Use LSB (Lower Sideband) on HF for AFSK; ensure normal polarity (mark high).
Frequencies: Avoid voice segments. Key spots: 80m (3.570-3.600 MHz), 40m (7.035-7.100 MHz), 30m (10.130-10.140 MHz), 20m (14.070-14.100 MHz), 15m (21.070-21.110 MHz), 10m (28.070-28.120 MHz). During contests, activity spreads.
Tune your radio to the mark frequency, keep power low to avoid distortion, and use slow AGC for better decoding.
Chapter 4: Radios and Transceivers Supporting RTTY
Many modern HF transceivers support RTTY natively via FSK or AFSK. Here's a comprehensive list based on popular models:
Radio Model
Manufacturer
Bands/Modes
RTTY Support Details
Price Range (Approx.)
Icom IC-7300
Icom
HF/6m
Built-in RTTY decode/encode, FSK/AFSK, USB sound card
$1,000-1,200
Icom IC-9700
Icom
VHF/UHF (2m/70cm/23cm)
SSB/AM/FM/CW/RTTY, FSK
$1,500-1,800
Yaesu FT-991A
Yaesu
HF/VHF/UHF
RTTY/PSK31 built-in, AFSK/FSK
$1,000-1,200
Yaesu FTDX10
Yaesu
HF/6m
Advanced digital modes, FSK/AFSK, roofing filters for clean RTTY
$1,300-1,500
Yaesu FT-710
Yaesu
HF/6m
Digital mode support, AFSK
$900-1,100
FlexRadio FLEX-6400
FlexRadio
HF/6m
SDR with native RTTY via software, high dynamic range
$2,000-2,500
Elecraft KX2/KX3
Elecraft
HF
Built-in RTTY/PSK31, portable, AFSK
$800-1,200
QRP Labs QMX
QRP Labs
HF
CW/FT8/RTTY capable, low-power portable
$100-200
Kenwood TS-590SG
Kenwood
HF/6m
FSK/AFSK, built-in decoder
$1,200-1,400
Icom IC-7610
Icom
HF/6m
Dual-watch for RTTY, advanced filters
$3,000+
For older radios without native support, use AFSK with a sound card interface. Ensure the radio has a data port or ACC jack for FSK. High-duty-cycle modes like RTTY require radios rated for continuous operation at reduced power (e.g., 50% of max).
Chapter 5: Interfaces and Sound Cards for Computer-Radio Connection
Connecting your computer to the radio is crucial for AFSK RTTY. Use a digital interface to isolate audio and control PTT (Push-To-Talk).
Popular Interfaces:
SignaLink USB: Built-in sound card, USB-powered, radio isolation. Setup: Connect to radio's data port, install drivers, select in software. Great for beginners.
RIGblaster: Models like Advantage or Nomic offer sound card, CAT control, FSK keying. Supports multiple radios.
microHAM DXP: High-res 24-bit ADC/DAC, portable, low noise for weak signals.
EASY DIGI: Budget kit for PSK/RTTY, supports FT8 too. Assemble and connect via USB.
Unified Microsystems SCI-6: Affordable kit, easy assembly for digital modes.
For sound cards, use external USB ones (e.g., cheap $5 adapters) to avoid PC noise. In software, set audio levels to avoid ALC activation—aim for 50% drive. For FSK, radios like IC-7300 need no extra interface if using built-in USB.
Chapter 6: Computer Software for RTTY: Selection, Setup, and Usage
Software decodes/encodes RTTY signals. Top options:
MMTTY: Free, dedicated RTTY engine. Excellent for contests with multiple decoders.
Setup: Download from hamsoft.hamradio.ca. In Options > Setup: Set baud to 45.45, shift 170 Hz, demodulator to FFT. For AFSK, use sound card; for FSK, EXTFSK. Integrate with N1MM+ for logging: Config > Digital Modes > Add MMTTY path.
Usage: Tune to signal, click to decode. Use macros for CQ calls: e.g., "CQ TEST DE N4YWD N4YWD K". Monitor waterfall for shifts.
FLDIGI: Free, multi-mode (RTTY, PSK, etc.). Strong weak-signal decoding.
Setup: Download from w1hkj.com. Config > Modems > RTTY: Baud 45.45, shift 170, LSB. Sound card via PortAudio. Pair with FLRIG for CAT control.
Usage: Waterfall display for tuning. Right-click for macros. Good for casual ops; integrate with N1MM+ for contests.
N1MM Logger+: Contest-focused, integrates MMTTY/FLDIGI/2Tone.
Setup: Install, add digital window. Mode Control: Set RTTY to AFSK/FSK. Use for scoring, dupe checking.
Usage: Pre-program exchanges like serial numbers. Dual decoders for better copy.
Other: 2Tone for auxiliary decoding, WriteLog for advanced contesting. Tips: Calibrate sound levels, use filters (500 Hz bandwidth), practice with simulators.
Chapter 7: Antennas Best Suited for RTTY
RTTY thrives on HF bands, so efficient HF antennas are key. Focus on low-angle radiation for DX, multi-band capability.
Top Recommendations:
End-Fed Half-Wave (EFHW): Versatile, covers 80-10m with tuner. Easy install: 130ft wire, balun. Great for portable ops, low noise.
Dipole: Classic, resonant on target bands (e.g., 40m dipole at 66ft). Inverted-V for space savings. Multi-band with traps or fan design.
Vertical Antennas: Like Hustler 6BTV or Comet GP6 (VHF too). Ground-mounted with radials for omnidirectional DX. Excellent on 40m/20m.
Yagi Beams: For gain, like Diex 4-element on 10m. Directional, ideal for contests. Hex-Beam for multi-band.
Portable Options: JPC-12 vertical (7-50 MHz), slide regulator for tuning. Perfect for field use.
General Tips: Height >30ft for better propagation. Use low-loss coax, tuner for SWR <2:1. For RTTY's high duty cycle, ensure good grounding to minimize RFI.
Chapter 8: Operating RTTY: Tips, Contests, and Best Practices
Start with listening: Tune to active frequencies, decode signals. For first QSO: CQ "DE [Your Call] K". Exchange RST, name, QTH.
Contests: ARRL RTTY Roundup (30 hours, exchange state/province); CQ WW RTTY (48 hours, zone/serial). Tips: Use S&P (Search & Pounce) for beginners; run CQ for multipliers. Space signals 250-500 Hz apart. Slow AGC, TX filtering to reduce errors. Macros for efficiency: "TU 599 001 001 BK".
Advanced: Dual decoders (MMTTY + 2Tone), SO2R (Single Op 2 Radios) for big scores. Practice with simulators. Avoid non-amateur confirmations.
Troubleshooting: Garbled text? Check polarity/shift. Weak signals? Narrow filters, preamp.
For more, explore rttycontesting.com and my site https://www.n4ywd.com.
Appendix: Resources and Glossary
Resources: AA5AU's Guide, Contest University PDFs, YouTube tutorials.
This guide draws from extensive sources to provide a deep, practical dive into RTTY. Experiment and enjoy!
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