LDMOS RF AMPLIFIER LINEARIZATION USING

POWERSDR MRX PURE SIGNAL Mike Seguin, N1JEZ

MID-ATLANTIC STATES VHF CONFERENCE 2014

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OPENHPSDR HERMES

• DUC/DDC ARCHITECTURE

• CONTINUOUS UNINTERRUPTED RECEIVE COVERAGE FROM 10KHZ TO 55MHZ

• MULTIPLE RECEIVER SUPPORT @ 48/96/192/384 KHZ BW

• FULL DUPLEX OPERATION - ANY SPLIT OVER ENTIRE 160M TO 6M RANGE

• 500MW RF OUTPUT ON 160 – 10M, 350MW ON 6M

• SOFTWARE-SELECTABLE 31dB INPUT ATTENUATOR IN 1dB STEPS

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OPENHPSDR HERMES

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POWERSDR MRX PS

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PURE SIGNAL

• DR. WARREN PRATT, NR0V – PRIMARY ARCHITECT OF PURE SIGNAL • RECIPIENT - ARRL TECHNICAL INNOVATION AWARD 2014

• "PREDISTORTION“ - THE SOFTWARE "PREDISTORTS" THE INPUT SIGNAL

TO THE AMPLIFIER TO CORRECT FOR NON-LINEARITIES IN THE OUTPUT

• “ADAPTIVE PREDISTORTION” - CONTINUOUSLY MONITORS OUTPUT VS INPUT AND MAKES CHANGES BASED ON VARYING CONDITIONS

• FINITE “CORRECTION BANDWIDTH” OF 40 KHZ OR +/- 20 KHZ FROM THE CENTER TRANSMIT FREQUENCY

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PURE SIGNAL

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Hermes Class A Driver

LDMOS Amplifier

Anritsu MS2721

Dielectric Wattmeter

Bird Sniffer

Bird kW Load

TEST SETUP

50.140 MHz TWO TONES @ 300 WATTS AVG

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FEEDBACK SIGNAL IS SET 1 dB BELOW ADC OVERLOAD

CLASS A DRIVER RD16HHF1 MOSFET

0.5 watts in – 5.0 watts out

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LDMOS AMPLIFIER NXP BLF-178

6M kW

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Yaesu FT-817

FUNcube HDSDR

software

Pad

IF TAP

TEST SETUPS - OTA

ANAN-100

FT-817 using 68.33 MHz IF Tap FUNcube Dongle HDSDR Software

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Hermes Based PowerSDR mRX PS

THE PERFECT AMPLIFIER

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IN REALITY….

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PURE SIGNAL CORRECTION

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HERMES WITH PURE SIGNAL OFF

IMD3 = -46.30 IMD5 = -52.91

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HERMES WITH PURE SIGNAL ON

IMD3 = -63.93 IMD5 = -77.71

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HERMES WITH PURE SIGNAL OFF PowerSDR mRX PS

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HERMES WITH PURE SIGNAL ON PowerSDR mRX PS

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CLASS A DRIVER WITH PURE SIGNAL OFF

IMD3 = -40.16 IMD5 = -49.82

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CLASS A DRIVER WITH PURE SIGNAL ON

IMD3 = -61.20 IMD5 = -75.25

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LDMOS WITH PURE SIGNAL OFF

IMD3 = -38.02 IMD5 = -41.90

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LDMOS WITH PURE SIGNAL ON

IMD3 = -54.48 IMD5 = -65.18

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Hermes Driver LDMOS

HDSDR WATERFALL OTA

PURE SIGNAL OFF

PURE SIGNAL ON

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AMPVIEW CLASS AB SSB 1.5A IDQ

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AMPVIEW CLASS AB SSB 1.5A IDQ

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AMPVIEW CLASS AB SSB 2A IDQ

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SUMMARY CLASS AB

• PURE SIGNAL LOWERS IMD

• PROVIDE A GOOD CLEAN FEEDBACK SIGNAL FOR PURE SIGNAL

• PAY CLOSE ATTENTION TO THE FEEDBACK SIGNAL LEVEL

• MY SIGNAL IS TOO CLEAN – NOW OTHER OPERATORS ARE GOING TO TUNE RIGHT NEXT TO ME AND SPLATTER ALL OVER ME

• POWERSDR MRX PS HAS A NEW ADDED FEATURE ON THE RIGHT SIDE OF THE SCREEN

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SPLATTER MODE

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SPLATTER MODE ON

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CLASS B LINEARIZATION?

• Is Pure Signal robust enough?

• Normal Class AB bias @ 1.5 A

• ~ 75 watts heat dissipated

• Class B set for 100 ma

• ~ 5 watts heat dissipated

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LDMOS CLASS B WITH PURE SIGNAL OFF

IMD3 = -22.40 IMD5 = -28.36

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IMD3 = -55.57 IMD5 = -63.04

LDMOS CLASS B WITH PURE SIGNAL ON

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HDSDR WATERFALL OTA

PURE SIGNAL OFF

PURE SIGNAL ON

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LDMOS CLASS B WITH PURE SIGNAL OFF

-31.8 in 3 kHz -31.2 Peak

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LDMOS CLASS B WITH PURE SIGNAL ON WHY DOES THE SIGNAL INCREASE?

-28.3 in 3 kHz -28.0 Peak

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LDMOS CLASS B WITH PURE SIGNAL OFF

Channel Pwr -28.49 Pwr Density -63.27 dBm/Hz

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LDMOS CLASS B WITH PURE SIGNAL ON WHY DOES THE SIGNAL INCREASE?

Channel Pwr -25.20 Pwr Density -59.97 dBm/Hz

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AMPVIEW CLASS B 2 TONE 100MA IDQ

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AMPVIEW CLASS B 2 TONE 100MA IDQ

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AMPVIEW CLASS B SSB 100MA IDQ

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AMPVIEW CLASS B SSB 100MA IDQ

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SUMMARY CLASS B

• PURE SIGNAL LOWERS IMD

• IT LINEARIZES THIS LDMOS CLASS B AMP

• MY SIGNAL IS TOO CLEAN – NOW OTHER OPERATORS ARE GOING TO TUNE RIGHT NEXT TO ME AND SPLATTER ALL OVER ME

• JUST TURN OFF PURE SIGNAL

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THE BLUE THUNDER – 2 PILL WONDER!

Property of W1GHZ

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28 MHZ AMPLIFIER – 2 PILL DEVICES ARE 2SC2290 - 60 WATTS PEP EACH

AMP TESTED AT 125 WATTS

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BLUE THUNDER WITH PURE SIGNAL OFF

IMD3 = -17.89 IMD5 = -27.74

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BLUE THUNDER WITH PURE SIGNAL ON

IMD3 = -47.60 IMD5 = -53.75

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LDMOS RF AMPLIFIER LINEARIZATION USING

POWERSDR MRX PURE SIGNAL Mike Seguin, N1JEZ

QUESTIONS?

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