‰  NOW 30 WPM  ‰  TEXT IS FROM JANUARY 2016 QST  PAGE 30‰

SDRSHARP. COM.  THE COMPANY GRACIOUSLY PROVIDES THE SOFTWARE FREE OF
CHARGE, AND ALSO SELLS THEIR VERSION OF A SOFTWARE DEFINED RADIO AS WELL AS
OTHER PLUG INS TO ADD FEATURES SUCH AS SCANNING.  THE LOWER FREQUENCY LIMIT
OF THE DONGLE IS AROUND 24 TO 25 MHZ.  THESE DONGLES WERE DESIGNED FOR
TELEVISION AND COMMERCIAL FM RADIO RECEPTION.  WHEN RE PURPOSED FOR HF HAM
USE, AN UPCONVERTER IS NECESSARY TO ALLOW RECEPTION IN THE 1 KHZ TO 30 MHZ
RANGE.  MY UPCONVERTER CONTAINS JUST A FEW COMPONENTS AND IS VERY SIMPLE TO
BUILD.  IT CONVERTS THE BELOW 30 MHZ FREQUENCIES UP TO A RANGE THAT THE USB
DONGLE CAN RECEIVE.  THE SCHEMATIC SEE FIGURE 2 ILLUSTRATES THE SIMPLICITY
OF THIS RECEIVER.  COMBINE THE DONGLE, A SWITCH, SOME ANTENNA CONNECTORS, A
MIXER AND OSCILLATOR, A POWER SOURCE FOR THE OSCILLATOR, AN LED, A FEW
WIRES, AND AN ENCLOSURE, AND YOU HAVE A COMPLETE RECEIVER.  ALL THE COMPLEX
CIRCUITRY IS ALREADY BUILT INTO THE DONGLE, AND ALL ADJUSTMENTS ARE DONE
VIA USERFRIENDLY SOFTWARE.  THEORY OF OPERATION THE 100 MHZ OSCILLATOR Z2
GENERATES AN RF SIGNAL THAT FEEDS A DOUBLE BALANCED MIXER Z1.  THIS MIXER
CONVERTS THE BELOW 30 MHZ FREQUENCIES SUPPLIED BY AN ANTENNA THROUGH THE 35
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ