I have attached links to three .JPG images of the K3's audio response as measured at the headphone jack with SpectraPlus FFT software. Response passband was normalized for both modes. SSB is measured through the 6K filter, and CW through the 8-pole 2.8 kHz filter. However, V3.33 SSB was taken with Fc = 1.35.
It would have made more sense to capture the responses such that three SSB plots would overlay on one graph and three CW plots on a second, but that took too much time in waiting for the firmware to load between plots. Still, you can see radical differences between firmware versions in the kinks below. Rx Band-1 EQ seems operational now too :-)). http://216.229.20.37/images/K3-V325.jpg http://216.229.20.37/images/K3-V330.jpg http://216.229.20.37/images/K3-V333.jpg As you can see, CW with V3.25 has the strongest low-end response relative to 1 kHz, but that can be compensated for with the first two EQ bands. Even as it is, if you draw a horizontal line mid-way through the V3.33 plots, that represents roughly +/- 2.5 dB from 20 Hz through 3.5 kHz. Not too shabby for a communications receiver. As a further experiment, I just added 3 dB to Rx bands 1-3 and the response is now essentially +/- 0dB between 20Hz and 3.5 kHz in SSB through the 6K filter and Fc = 1.35. You can lay the ruler flat on the response. http://216.229.20.37/images/K3-V333-EQ.jpg Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
