Which HF Transceiver is Best for Me?

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

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

3. 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!

4. Reference SourcesMost 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

5. 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!

6. 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!

7. 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”

8. Price and FeaturesA Balancing Act • Price • 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

9. 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

10. 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

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

12. Mixers Mix Everything at Their InputsPhase 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

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

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

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

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

17. 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

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

19. Listening FatigueHow 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

20. Listening FatigueHow 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

21. AGC Controls • 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

22. AGC Control Examples AGC Threshold AGC Slope C L

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

24. Transmitter-Specific CriteriaKnow 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)

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

26. CW Rise TimeA 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

27. ALC 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 4 kHz -60 dB ALC Half Scale No ALC 60 dB down 1.8 kHz away

28. 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

29. 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

30. ErgonomicsAccess 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

31. “Intangibles” • Reliability • 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

32. 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!”