After several years of faithful service, my K2/100 (with KDSP2 and KSB2) has developed a perplexing malady. The crystal filter passband will not adjust to center on a 600hz sidetone. As you adjust the filters towards 600 hz using Spectrogram (say OP1), the filter shape degrades and then severely attenuates the signal until NO audio signal is visible on the Spectrogram display. I have repeated the key realignment procedures three times, with identical results.
The long story. The K2/100 generated an Info 080 message that I started diagnosing. The problem "self-corrected" which lead me to believe it was probably a loose connection to the KPA100. Despite lots of opening and closing the case, the problem has not reappeared. I now have better test equipment than I had when I built the K2 (serial 4357) and it seemed like a good time to realign the transceiver. I did a complete realignment, with minimal changes except a slight kick to the 4Mhz oscillator and a reasonable amount of repeaking of the bandpass filters. So far so good. All of the key tests/parameters were within range. When I started to set the filters, however, I could not get them within range. As noted above, I can not shift the passband to cover a 600hz sidetone. The filters appear to center around 900-1000 hz. I have attempted to set the filters back to my prior CAL FIL BFO settings, but to no avail. The following are the test results from this realignment. PLL Reference Oscillator Range Test High = 12101.55 Low = 12088.14 Dif = 13.44 (Acceptable 9.8 - 15) VCO Voltage all greater than 1.5 v, less than 7.5 v. BFO Test BFO High = 4917.42 (Acceptable >= 4916.3) BFO Low = 4912.34 (Acceptable <= 4912.7) Range = 5.08 (Acceptable >= 3.6) Transmit frequency is +- 10 hz. However, zero beating a 600hz sidetone against the 7.00 Mhz birdie **appears** to be around 7000.35 Khz. (I never fully trust zero beating as I am tonally challenged...) Any ideas?? Howard W. Ashcraft, Jr. Hanson, Bridgett, Marcus, Vlahos & Rudy 425 Market Street, 26th Fl. San Francisco, CA 94105 ph: 415.995.5073 fax: 415.541.9366 e: [EMAIL PROTECTED] ***************************** This communication, including any attachments, is confidential and may be protected by privilege. If you are not the intended recipient, any use, dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by telephone or email, and permanently delete all copies, electronic or other, you may have. To ensure compliance with requirements imposed by the IRS, we inform you that any tax advice contained in this communication (including any attachments) was not intended or written to be used, and cannot be used, for the purpose of (i) avoiding penalties under the Internal Revenue Code or (ii) promoting, marketing or recommending to another party any transaction or matter addressed herein. The foregoing applies even if this notice is embedded in a message that is forwarded or attached. ***************************** _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
