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LAB NOTES THE STATE OF THE ART TECHNOLOGY AND CONSTANTLY IMPROVING
PERFORMANCE OF THE ELECRAFT K4D KEPT ME BUSY IN THE ARRL LAB.  TABLE 1 AND
THE KEY MEASUREMENTS SUMMARY SHOW CONSISTENTLY GREEN PERFORMANCE ACROSS THE
BOARD.  IN JANUARY, THE ARRL BOARD OF DIRECTORS APPROVED THE CLEAN SIGNAL
INITIATIVE PROGRAM, TO SET A HIGH STANDARD OF TRANSMITTER PERFORMANCE TO
HELP CLEAN UP THE BANDS FROM TRANSMIT IMD SPLATTER, KEY CLICKS, AND
TRANSMITTED PHASE NOISE, TO NAME A FEW EXAMPLES.  ALTHOUGH THE PROGRAM IS
NOT YET READY TO FEATURE THE K4D UNDER ITS BANNER, PERFORMANCE SUCH AS THE
THIRD ORDER TRANSMIT IMD AND 5 KHZ SPACING KEYING SIDEBANDS IS STELLAR.
THE SDR IMPLEMENTATION IS ALSO STATE OF THE ART, WITH THE USE OF BANDPASS
FILTERS IN THE RECEIVE CHAIN TO HELP THE RECEIVERS WORK WELL IN MULTI
TRANSMITTER ENVIRONMENTS.  THE DESIGN MAKES USE OF MULTIPLE FPGAS AND
MULTIPLE DSP CHAINS TO IMPLEMENT OR IMPROVE FUNCTIONS LIKE DIVERSITY
RECEPTION AND STRONG SIGNAL PERFORMANCE.  FOR MORE INFORMATION ABOUT THE
DESIGN, SEE HTTPS// ELECRAFT. COM FOR DETAILS.  NOTABLY, ELECRAFT HAS
IMPLEMENTED CONTROLLED ENVELOPE SINGLE SIDEBAND COMPRESSION TO GREATLY
ENHANCE TALK POWER.  THIS WAS FIRST DESCRIBED IN AN ARTICLE BY DAVID
HERSHBERGER, W9GR, IN THE NOVEMBER/DECEMBER 2014 ISSUE OF QEX.  THE LABS
PRELIMINARY MEASUREMENTS SHOWED AN IMPRESSIVE INCREASE IN TALK POWER OF
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