This afternoon I made a 3-1/2 minute audio recording of two stations in QSO with each other on 40 CW, using both a K3 and K4D, and switching back and forth. Download here (2.3 MB):
https://www.kkn.net/~n6tv/K3_vs_K4D_CW_Audio_by_N6TV_20200625.mp3 Recorded off rear headphone jack using an MK2R+ USB Sound Card. In sum, I think the K4D audio sounds quite a bit better, but the "500 Hz" passband of the K4 seems wider than the K3 (wider skirts?). The AGC attack time seems slower in the K4 (similar to Icom IC-7851 fast AGC, IMHO). So the "leading edge" of each dot or dash is louder, which may improve copy a bit. The loud station (about 599 + 10 dB) is AC2K in AZ, and the weaker one (about S-6 to S-7) is NZ0T in MO. Timestamp What you're hearing ------------ ------------------- 00:00 - 00:16 K3 00:19 - 01:00 K4 01:01 - 01:21 K4 with NR engaged and adjusted for best copy ("Level 3") (Tuned range 0 to 10, the complete range) 01:22 - 01:25 K3 01:26 - 01:58 K3 with NR F1-2 (didn't adjust) 02:00 - 02:35 K4 NR off I think 02:37 - 03:10 K3 NR off 03:13 - 03:20 K4 K3 is S/N 1495 with KSYN3A upgrade but original DSP board and Inrad 500 Hz 8-pole CW crystal filter, with W9AC Audio Mod <http://web.archive.org/web/20091011115528/http://n1eu.com/K3/k3audiomod.htm>. (capacitors changed in headphone circuit to increase low end audio response) K4D Field Test Unit S/N 0008 K3 and K4 were set with identical parameters where possible: AGC-F, ATT OFF, PRE OFF RF Gain about 3 O'Clock on K3. RF Gain 0 (max) on K4 CW mode, 500 Hz bandwidth Pitch 480 Hz / center of passband IF shift AGC Attack: 210 (K4 only) AGC DCY Soft (K3 only) AGC HLD 0.05 (K3 only) AGC PLS NOR/ON AGC SLP 008 (K3) AGC Slope 15 (K4 -- units are different) AGC THR 010 (K3) AGC Threshold 4 (K4 -- units are different) AGC-F / AGC Decay, Fast:120 AGC-S / AGC Decay, Slow: 20 73, Bob, N6TV ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
