Which HF Transceiver is Best for Me? Brian Machesney, K1LI

What's the Best HF Transceiver for Me? Tips on Radio Selection Strategy Brian Machesney K1LI

Goal of this Presentation Arm you with a strategy to choose a radio that’s appropriate to your individual situation A number of radios will be used to illustrate various criteria, but any radio can be evaluated in the same way NOT to promote or disparage any radio or brand vs. any other… but my own definition of value will inevitably creep in I invite you to comment on your own definitions of value!

Reference Sources Most of this material came from somewhere else… Sherwood Engineering: RMDR, IMDR measurements ARRL Product reviews: lab-grade testing, plus color commentary “Test Procedures Manual”: measurement methods VA7OJ, I2VGO, Linearizer Technology Inc.: noise power ratio Clifton Laboratories: AGC measurements Audio Systems Group: compiled transmitter spectra from ARRL Lab Company and distributor materials eHam classifieds: used equipment prices

Situations New ham – bewildering amount and variety of information Capability upgrade – more effective communications Use modes Casual vs. competitive Home vs. road Standalone vs. transverter Dominated by CW / SSB / Digital Your predilection here!

How did you choose your last radio How did you choose your last radio? … and how do you feel about that decision today? Opinions of personal or on-air acquaintances On-air observations Online, magazine reviews Company web sites, hamfest exhibits, email reflectors Online chat room, special interest group web site Technical blogs Previous experience with a brand or model e.g., at your local / favorite multi-multi contest operation!

Radio Selection Criteria Price and “features” – one piece of an entire station Receiver – you can’t work ‘em if you can’t hear ‘em Transmitter – you mean, this matters? Interface – logging programs, digital modes Ergonomics – initial setup, on-the-air operation “Intangibles”

Price and Features A Balancing Act New vs. “pre-owned” Recent models may have significant hardware revisions Band coverage, transverter interface Output power, ATU Display “Character” vs. “Graphical” Bandscope, touchscreen menu buttons Interface convenience Upgrade path: filters, functions, features Power supply: internal vs. external Size, weight

Receiver-Specific Criteria Ability to hear desired signals Sensitivity No longer an issue at HF vs. atmospheric noise May be important if you want to use with transverter Selectivity Hardware – L-C, ceramic, crystal, mechanical filters Software – DSP – bandpass, notch, noise reduction Distortion – audible “junk” created in the receiver Listening fatigue – how it “sounds” Audio distortion Response to impulse noise

Contesting: a Dynamic Environment “Running” produces higher scores than “S&P” “Loud” stations do more running “Not loud” stations do more S&P If you’re running, “not loud” stations will be calling you … … while you are surrounded by other “loud” stations When you S&P, you may be calling “not loud” stations… … while they are surrounded by “loud” stations CQ WW 2014 log submissions Power CW SSB High 3011 (41%) 3240 (41%) Low 3821 (52%) 4337 (55%) QRP 505 (7%) 344 (4%)

Simplified Receiver Block Diagram What Could Possibly Go Wrong?! Local Oscillator IF Amp, Detector Audio Amp Preselector IF Filter Antenna Speaker Active stages are not perfectly linear Active and passive stages can overload Mixing is multiplication: inherently nonlinear! Mixers mix everything at their inputs RF Input   Local Oscillator Image Desired IF Output Amplitude Frequency IF Filter Passband

Mixers Mix Everything at Their Inputs Phase noise, distortions “smear” spectra Real world oscillators produce noise sidebands Amplifier nonlinearities, ALC, CW rise/fall times spread the spectra of input signals Multiple signals appear at the mixer’s RF input Result: noisy jumble in the IF   LO Amplitude Desired IF Output Image RF       Frequency

Reciprocal Mixing (RM) “…noise generated [by] the mixing of the First Local Oscillator’s Phase Noise and a strong adjacent, steady signal.” “Clean” RF source Measurement Setup Step Atten Receiver 14.023 14.027 14.025MHz ANT Audio Distortion Meter Low-noise XTAL Osc SPKR   LO Amplitude   Desired IF Output Image RF         Frequency

Price* (USD) RMDR (dB) = SRF (dBm) - MDS (dBm) Notes: Flex6700 TS990 Notes: * RED = retail, BLACK = used IC7700 TS990 FTDX5000 Flex6300 IC7700 Price* (USD) IC9100 IC7600 K3? Flex5000 KX3 FTDX3000 TS590 K3 Eagle Flex3000 756P2(IR) TS590  

Intermodulation Distortion (IMD) “…range of signals that can be tolerated by the [receiver] while producing essentially no undesired spurious responses.”   Hybrid Combiner Receiver 14.002 ANT Audio Distortion Meter RF Gen 2 14.000 SPKR 2-kHz Measurement Setup Signal Analyzer RF Gen 3 14.002 Step Atten RF Gen 1 13.998     LO Amplitude Desired IF Out 1 2 IMD RF 1 2 Image IMD 2 1       Frequency

Price** (USD) IM3DR (dB) = SRF (dBm) - MDS (dBm) Flex6700 TS990   IC7700* TS990 IC7800* FTDX5000* Flex6300 IC7700* Price** (USD) K3 IC7600* IC9100 OrionII OmniVII FT2000 Flex5000 756P2(IR) FTDX3000* K2* TS590* KX3 FT1KMPV(IR) Orion K3* FT1KMP(IR) ArgVI* Flex3000* IC7000 FT1000D 756P2 OmniVI+ Eagle* TS590* IC756P TS830S/YK88  

Noise Power Ratio (NPR) “… white noise is used to simulate the presence of many carriers of random amplitude and phase.” NPR Measurement Setup Tune RX to fnotch

No clear correlation vs. IM3DR A new “numbers race?”   No clear correlation vs. IM3DR A new “numbers race?” IC7700 IC7800 K3 Noise Power Ratio (dB) (VA7OJ) IC7600 IC9100 FT950 TS590 KX3 FT1KMP-V IC7000 Flex6700 FTDX3000  

Listening Fatigue How the Radio “Sounds” Commonplace “10% THD” spec produces tiring audio Distortion -20dB from desired signal Example IC756 Pro III must be driven into clipping to meet the 2 W into 8 ohm brochure spec. Many audible spurs Spurs disappear at lower audio output <0.1% distortion Easy to listen for long periods  

Listening Fatigue How the Radio “Sounds”   Early K3 users complained about “scratchy” audio 40dB down = 1% distortion Many audible spurs Adding output choke attenuated spurs 0.1% distortion Easy to listen for long periods  

AGC Controls C L Purpose Reduce distortion Prevent damage to operator! Implementation: reduce gain in presence of strong signals How fast and how much? Then what? Optimizing AGC parameters key to performance in wide range of signal environments e.g., shape of decay action can affect AGC-related IMD C L

AGC Control Examples AGC Threshold AGC Slope C L

AGC Response to Impulse Noise Slow AGC recovery = poor copy Faster AGC recovery = better copy  

Transmitter-Specific Criteria Know the properties of your transmitted signal CQ WW rules: “Signals with excessive bandwidth (e.g., splatter, clicks)” may disqualified for unsportsmanlike conduct” SSB: optimize audio chain for communicating effectiveness Mic: “pin 1” problem Frequency tailoring: accentuate the positive, eliminate the negative Amplitude compression: AF vs. RF, level Background noise: clean transmission and clean reception (AGC) CW: control rise/fall for “appropriate” bandwidth Digi: internal vs. external signal generation ALC behavior (ATU matching range)

Transmitter: ARRL Lab Test Data* Revealing side-by-side comparisons 60WPM Keying Spectral Data * Mfgr data for Flex  

CW Rise Time A Little Goes a Long Way 1 “dit” time = 1.2/WPM (W5ALT) 30WPM  1 dit = 40ms 50WPM  1 dit = 24ms 10ms rise, fall fast enough! TR=3ms TR=10ms  

ALC ALC too fast: distortion, IMD Rig power set to 50W ALC too fast: distortion, IMD ALC too slow: overshoot could damage linears that only need 40 to 60 watts of drive ALC overshoot often worse at reduced power ALC “artifacts” can be very troubling No ALC ALC Half Scale 60 dB down 1.8 kHz away 4 kHz -60 dB  

PC-to-Rig “Direct” Interface Example Analog Interface: Line In / Line Out “Soundcard” digital modes SSB “digital voice keyer” (DVK) Digital voice (e.g., FreeDV) Digital Interface: RS232, USB, FW CW: LPT is dead! SSB: built-in DVK Digi: “native” DSP capabilities

Soundcard-to-Rig Interface Example Isolates transmit and receive audio PTT, CW, FSK rig control COM or USB Essential: compatibility between interface S/W, OS, interface and rig

Ergonomics Access to radio controls Setup: menu confusion? Most-used operational controls Knob/button/readout size, spacing, grouping Confounded multi-functions? Visibility from operating position Display – too “busy?” Controls – label size, color? Keyboard-radio reach fatigue Physical size, weight Where is the radio? ergo.human.cornell.edu/AHTutorials/typingposture.html

“Intangibles” Reliability Serviceability What breaks? How often? Serviceability Foreign vs. domestic service depot Discontinued support ROHS and older radios Manufacturer, distributor longevity “Crowd” support and online discussion groups

Decisions, Decisions, Decisions There’s a lot to consider when choosing an HF transceiver Winner may not be obvious Make a list of your priorities “Score” candidates against your priority list Tally up the score to select a winner… … or choose a different radio for “intangible” reasons “I just had to try that radio!” Parameter Importance (1-5) Score (1-5) Parameter Score A 5 4 20 B 16 C 3 15 D 2 Total 55