SADLY, with the heavy focus on Receive Performance during the past 25 years, hams have lost focus on transmitter performance.
Receivers have made a quantum leap in performance in important areas like blocking dynamic range. There is no such thing as a transceiver these days that does not have enough RX sensitivity.
But let's take a look at what has happened to our transmitters.
BE PREPARED FOR A SHOCK!
QUICK INTRODUCTION TO THE PROBLEM:
Lief Asbrink, SM5BSZ has written an excellent paper introducing us to the broadband noise problem.
Keep in mind that this is only part of the problem (atrocious IMD problems are the other part), but his is a good place to start.
NOTE: The radio listed in the second line of the Table is a Ten-Tec "TT-599AT", (not TS-599AT); its a typo.
And excellent article telling us about one of the TX Noise Problems with many of today's modern transceivers. SDR fanatics, TAKE NOTE!
Transmitter Noise Article dubus313.pdf
PDF-Dokument [553.2 KB]
More Measured Data (by K9YC)
The ARRL has measured this information but not done much to publicize it. Jim Brown, K9YC has recapped some of it, adding his own comments. In addition, he has included a page by Wayne Burdick, N6KR, the chief technical guru of Elecraft. Wayne explains what the cause of the problem is.
This document compares TX phase noise, as measured by the ARRL lab. It is commented on by Jim Brown, K9YC. The last page includes an explanation of what's wrong with many of today's radios, by Wayne Burdick, N6KR (of Elecraft)
PDF-Dokument [1.1 MB]