I find zero-beating the KX1 hard. 1. The KX1 mutes the RX, so I can't hear the sidetone and the signal at the same time. 2. I find the sidetone's rich harmonic content distracting.
Proposal: I think it would be desirable to clean up the sidetone audio, and to provide a mechanism to inject the sidetone into the RX audio for zero beat, perhaps with a menu item so that Menu-Hold could do it in one touch. Workaround: For now, I've taken to using the USB/LSB method, or actually tuning to zero and going up (or down depending on band) 600Hz. Details: 1. Sidetone and RX Muting The STL/STP sidetone test mode and PLY=non keyer test modes block out the RX so you can't listen for actual beats against the incoming signal; instead, you have to compare them. Perhaps I've assembled my kit incorrectly, but I found that even at STL 0 the sidetone is easily louder than most of the signals I hear so it seems like it would be possible to inject it without a problem. Wayne said the sidetone is driven from the PIC. and looking at the schematic I see it is from PIC outputs RC0 and RC1 combined through R12 and R13. It looks like MUTE-bar comes from RA4, so it should be possible to do this with a firmware change. I suppose I could test it by removing R29... 2. Sidetone harmonic content A second problem for me is the rich harmonic content. When set at 600Hz, I see a strong component at 1800 and 3KHz and a weaker one at 1200. As an experiment I tried listening through an audio filter (an Autek QF-1A) and found it much easier to tune by pitch matching. For the more musically-challenged of us, it might be desirable to round off the sidetone a little more. At first thought that C2 and R15 were a low-pass filter, but 37KHz seems a bit high so I'm confused. If the two PIC outputs RC0 and RC1 are used only to provide the 4 levels, it might be possible to use them (at least in zero-beat mode) to generate a slightly better sine wave with values 0-3. Unfortunately, that would mean increasing the value of R12 and R13 which might cause an undesirable reduction in sidetone volume during TX. Leigh WA5ZNU _______________________________________________ Elecraft mailing list Post to: [email protected] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com
