Tom km4cu wrote: Hello to all. First time posting herem glad to be a part of the Elecraft family. I have a K1, K2, xg-1. the K2 is having a problem with pitch differences, one bfo setting to another, the hard part is that sometimes it's perfect, other times not. Normally if there is a pitch difference, opt-1 is different. I have tried several times to get it correct but no success. I have used Spectrogram also.. Any suggestions??
------------------------------------------ Is it a new K2 Tom? (Or at least with a s/n >3000). Some pitch variation is normal. The digital circuits that reset the BFO frequency to that set up during CAL FIL have a resolution, or accuracy, that allows perhaps 20 or 30 Hz. However, it is generally stable from day to day. Older K2's had a BFO that drifted more than the current ones. The BFO, like any oscillator designed to change frequency, tries to change frequency on its own, usually in response to temperature changes. You may be experiencing some BFO drift if the degree if change when stepping through the filters varies from time to time. The drift issue with the older K2's was cured with a mod kit from Elecraft. The normal method of reducing the filter-to-filter variation to the minimum possible - assuming no BFO drift - is to force the K2 logic to re-read the BFO frequencies. You do that by putting the calibrator probe in the BFO test point like you did when running spectrogram, go into CAL FIL, and then change each BFO frequency setting to and different value, then put it back where it was. That movement causes the logic to re-read the BFO frequency and store a new, hopefully more accurate, value in memory. One thing to keep in mind is that you can *not* "tweak" the frequencies in CAL FIL while listening to a signal on the air. Only have noise in the bandpass. That's because the BFO and Local Oscillator (PLL Oscillator) frequencies interact to make changing the BFO frequency appear to make the I.F. bandpass move. There a good write-up on that on the Elecraft web site called "The Mechanics Behind CAL FIL". Ron AC7AC - _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
