‰  NOW 40 WPM  ‰  TEXT IS FROM JULY 2015 QST  PAGE 54‰
THE 80 METER AMATEUR BAND, PROVIDED THE USER STAYS AWAY FROM MULTIPLES OF
HALF WAVE LENGTHS OF WIRE.  IF A GROUND SYSTEM IS NOT AVAILABLE, YOU CAN
USE A COUNTERPOISE, PREFERABLY A QUARTER WAVELENGTH LONG FOR THE BAND IN
USE.  I DID JUST THAT AT MY BACKYARD SHED SHACK, USING WIRE SALVAGED FROM A
DISCARDED EXTENSION CORD CUT TO LENGTH FOR 40 METERS.  WITH A 33 FOOT
VERTICAL WIRE AND A 30 FOOT COUNTERPOISE, I ATTAINED NEARLY A 1 1 SWR WITH
THE MT 1 AND MADE SEVERAL DX CONTACTS WI

GETTING THE TRANSMITTER RUNNING AND USING IT ON THE AIR, BUT ASSUMES THAT
YOU ARE ALREADY FAMILIAR WITH THE RASPBERRY PI AND HAVE SET UP ITS
OPERATING SYSTEM, KEYBOARD, MOUSE, AND DISPLAY.  EACH MODE IS SUPPORTED BY
ITS OWN RASPBERRY PI PROGRAM THAT YOU INVOKE FROM THE LINUX COMMAND LINE.
THE GRAPHICAL FRONT END PROGRAM MENTIONED PREVIOUSLY MAY MAKE OPERATION A
LITTLE EASIER.  YOULL NEED TO DOWNLOAD THE SOFTWARE FROM RADWAVS WEBSITE.
WSPR OPERATION INVOLVES TRANSMITTING FOR 2 MINUTES AND WAITING FOR PERHAPS
6 MINUTES BEFORE SENDING AGAIN.  YOU NEED TO BE SURE THE PIS INTERNAL CLOCK
IS SET ACCURATELY, SO THAT THE MINUTE TICKS ARE ACCURATE WITHIN A FRACTION
OF A SECOND.  RADWAV WARNS THAT TRANSMITTING FOR LONGER THAN 2 MINUTES
RISKS OVERHEATING THE POWER TRANSISTOR.  THE PIS OSCILLATOR IS CRYSTAL
CONTROLLED AND STABLE, BUT NOT ESPECIALLY ACCURATE.  YOU WILL NEED TO
CALIBRATE IT AGAINST AN ACCURATE RECEIVER OR FREQUENCY COUNTER.  I FOUND MY
SIGNAL WAS RUNNING ABOUT 150 HZ LOW AT 7R04 MHZ.  THIS IS IMPORTANT,
BECAUSE THE ENTIRE WSPR BAND IS ONLY 200 HZ WIDE.  ITS EASY TO ADJUST YOUR
FREQUENCY SETTING BY CHANGING THE COMMAND LINE.  YOU CAN ADAPT THE PROVIDED

ACCOMPANYING PHOTO.  THE SKYPIS FUNCTION IS MAINLY TO PROVIDE POWER
AMPLIFICATION AND HARMONIC FILTERING.  AFTER BUILDING THE KIT, WE FOUND THE
CW KEYING WAVEFORM HAD A VERY SHORT RISE AND FALL TIME, PRODUCING EXCESSIVE
KEY CLICKS.  RADWAV SUPPLIED A REPLACEMENT BOARD THAT SHOWED GOOD RISE AND
FALL TIMES, AND THE CLICKS ARE GONE FIGURES 6 AND 7.  APPLICATIONS HOW TO
USE THIS COMPUTER TRANSMITTER?  ONE OBVIOUS APPLICATION IS AS A WEAK SIGNAL
PROPAGATION REPORTER WSPR BEACON.  IT ALLOWS THIS 1 W TRANSMITTER TO BE
HEARD AROUND THE WORLD BY STATIONS THAT REPORT THEIR RESULTS TO A WEB
DATABASE AND MAPPING SERVICE WSPRNET. ORG.  ALL YOU NEED IS A DIPOLE OR
OTHER 40 METER ANTENNA.  THE SKYPI ALSO SUPPORTS RTTY AND CW.  RTTY IS SENT
ONE COMMAND LINE AT A TIME.  WITH THAT LIMITATION, ITS PROBABLY MOST USEFUL
AS A BEACON BUT A GRAPHICAL FRONT END PROGRAM IS IN DEVELOPMENT THAT
INCLUDES MEMORIES FOR CW AND RTTY MESSAGES.  THE SKYPIS CW MODE TRANSMITS
ACCORDING TO A KEYING INPUT FROM ANY MORSE KEY.  AN OPTIONAL RECEIVER PORT
ALLOWS FULL BREAK IN TWO WAY QSOS ON CW WITH A SEPARATE RECEIVER.  THE PORT
IS ALWAYS ACTIVE, BUT IT IS LIMITED TO A SAFE LEVEL FOR ANY 40 METER
RECEIVER YOU WOULD LIKE TO ATTACH.  AS WE WERE FINISHING THIS REVIEW,
RADWAV ANNOUNCED A COMPANION RECEIVER, THE SKYPIRX, TO CONVERT THE SKYPI 40
INTO A TRANSCEIVER.  THE MANUAL INCLUDES QUITE A BIT OF INFORMATION ABOUT
‰  END OF 40 WPM TEXT  ‰  QST DE W1AW  ƒ