I am using a K3 that has been upgraded to include the KIO3B three board set with USB audio to the computer. For several years, it has been working well with my MacBook Pro.

Recently, my decoding of FT8/FT4 signals has become much worse. I see a large number of signals on the wsjt-x waterfall, but get very few decodes. I don't think this is a time of day problem as when I do get decodes the displayed times are on the order of 0.1 or 0.2 seconds. (I have played a lot to be sure NTP is working correctly.) I have also adjusted the RF gain to between 30 and 70 on the wsjt-x signal level display. Changing between 30 and 70 doesn't change the number of decodes.

I ran some experiments today to try to locate the problem.

(1) Since there was a RTTY contest in progress, I compared the decodes I was getting on the computer with cocoaModem with the ones I was getting from the K3's internal decoder. The K3's were significantly better.

(2) I played the FT8 subband through the radio's loud speaker and used the internal microphone on the computer to listen to the signals. I got a lot more decodes (and the times were consistant with a correct time setting on the computer).

I am starting to conclude that there may be a problem with the USB audio. I will try to hook up the external sound card I use with my KX3 tonight and see if it works better than the KIO3B.

Has anyone seen these symptoms? Do you have any fixes?

73 Bill AE6JV

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Bill Frantz        | There's nothing so clear    | Periwinkle
(408)348-7900 | as a design you haven't | 150 Rivermead Rd #235 www.pwpconsult.com | written down. - Dean Tribble| Peterborough, NH 03458

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