Transcript Slide 1
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? … 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 • 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 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?! Preselector IF Filter Speaker IF Amp, Detector Audio Amp Local Oscillator Amplitude • Active stages are not perfectly linear • Active and passive stages can overload • Mixing is multiplication: inherently nonlinear! • Mixers mix everything at their inputs Antenna Local Oscillator Desired IF Output IF Filter Passband RF Input Frequency Image Mixers Mix Everything at Their Inputs • 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 Amplitude Phase noise, distortions “smear” spectra LO Desired IF Output RF Frequency Image 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 Amplitude LO Measurement Setup Lownoise XTAL Osc 14.025MHz Desired IF Output Frequency RF Image Step Atten Audio Distortion Meter SPKR ANT Receiver 14.023 14.027 RMDR (dB) = SRF (dBm) - MDS (dBm) Flex6700 TS990 Notes: * RED = retail, BLACK = used IC7700 TS990 Price* (USD) FTDX5000 Flex6300 IC7700 IC9100 IC7600 K3? Flex5000 FTDX3000 KX3 TS590 K3 Eagle 756P2(IR) TS590 Flex3000 Intermodulation Distortion (IMD) • “…range of signals that can be tolerated by the [receiver] while producing essentially no undesired spurious responses.” 2-kHz Measurement Setup Amplitude RF Gen 1 13.998 RF Gen 2 14.000 LO Audio Distortion Meter Signal Analyzer SPKR Desired IF Out 1 2 IMD RF 12 Frequency Image IMD 2 1 Hybrid Combiner Receiver 14.002 ANT Step Atten Hybrid Combiner RF Gen 3 14.002 IM3DR (dB) = SRF (dBm) - MDS (dBm) Flex6700 TS990 IC7700* TS990 FTDX5000* Price** (USD) IC7800* Flex6300 IC7700* IC7600* IC9100 OmniVII OrionII K3 Flex5000 756P2(IR) K2* FTDX3000* TS590* Orion K3* KX3 FT1KMP(IR) FT1KMPV(IR) Flex3000* ArgVI* IC7000 Eagle* TS590* FT1000D IC756P 756P2 OmniVI+ TS830S/YK88 FT2000 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 Noise Power Ratio (dB) (VA7OJ) • No clear correlation vs. IM3DR • A new “numbers race?” IC7700 IC7800 K3 IC7600 IC9100 FT950 TS590 KX3 IC7000 FT1KMP-V 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 • 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 CL AGC Control Examples AGC Threshold AGC Slope CL 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 TR=3ms TR=10ms 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 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 4 kHz -60 dB ALC Half Scale • ALC overshoot often worse at reduced power • ALC “artifacts” can be very troubling 60 dB down 1.8 kHz away No ALC 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 ergo.human.cornell.edu/AHTutorials/typingposture.html “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 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 Score (1-5) (1-5) Parameter Score A 5 4 20 B 4 4 16 C 3 5 15 D 2 2 4 Total 55