++++++++++++++++++ To: elecraft at mailman.qth.net From: CHARLES K BROWN Date: Fri, 21 Jun 2002 11:26:53 EDT Subject: [Elecraft] CHU Frequency Calibration At least two of the CHU frequencies are within the frequency coverage of the K2. 3.330 and 14.670. When testing and experimenting with Spectrogram recently, I used the CHU carrier of the 14.670 signal for comparison with the display I had of the WWV signals. CHU Ottawa, Canada 3.330 7.335 14.670 N4SO Ken Brown Mobile, AL/EM50tk NorCal-20/5 watts/4 ele. beam N4SO at juno.com ++++++++++++++++++ Reply-To: "Don Wilhelm" From: "Don Wilhelm" To: , , Subject: Re: [Elecraft] Calibration with CHU via Spectrogram Software Date: Sun, 7 Jul 2002 11:11:43 -0400 Jim, Earl and all, You are correct that directly measuring the 4.000 MHz oscillator is likely to pull the frequency. The solution is to use the method outlined in the manual - connect BOTH the K2 internal frequency counter probe AND the external frequency counter to the same point (TP3), then adjust C22 so that both counters display the same frequency. This method will assure you that the 4.000 oscillator is set as close as the calibration and accuracy of your external counter will allow. Using WWV or CHU or other standard frequency involves an interative process - set C22, then run CAL PLL, check for zero beat, and do it again and again until you have it right... Using the external counter is much easier and straightforward. I guess you could fine tune to WWV or CHU after doing the initial adjustment with the external counter, but if you are within 20 Hz or so, I wouldn't bother for the K2 may drift as much as that, and would make attempts at further refinement just an exercize in frustration IMHO. 73, Don Wilhelm - Wake Forest, NC W3FPR home page: http://www.qsl.net/w3fpr/ QRP-L # 485 K2 SN 0020 mailto: w3fpr at arrl.net *** Life is what happens when you're making other plans -- Mike Cross *** ----- Original Message ----- > Tnx for the advice. Yes, I can use a freq counter but I'm afraid that > connecting a probe will pull the freq. Can also listen for the 4.000 MHz on a > receiver but then its only as accurate as that receiver. Perhaps this is > good enough but people are talking about accuracy within 30 Hz or so. I'd > like to use the method that has the best accuracy. Seems like fine-tuning to > atomic clock accuracy at least theoretically is the way to go. > Has anyone had good results with the CHU method? +++++++++++++++++++++ To: elecraft at mailman.qth.net From: n4so at juno.com Date: Sun, 29 Dec 2002 15:22:16 EST Subject: [Elecraft] Rubicon / vs. Rubidium frequency standards Rubicon - a river in northern Italy, or a line that when crossed commits a person irrevocably Rubidium, on the other hand, is a soft silvery metallic element ....bursts into flame spontaneously in air. timestn2.txt W1AW Morse code practice and Morse code bulletins (W1AW, while not a frequency standard, provides a quick check on Morse code transmission frequencies of 1.818 3.5815, 7.0475, 14.0475, 18.0975, 21.0675, 28.0675 at 1400z 2100z 2200z 0000z 0100z 0200z. The accuracy on 28 mhz is something like 28.067530, close enough for in band checks.) CHU Canada provides alternate frequencies to WWV. Checks with Spectrogram and CHU compared to WWV show them to be the same. The carrier is used, offsetting 1000 Hz, and noting the 1000 Hz marker in Spectrogram, MixW 2.06, Digipan. CHU 3330 7335 14670 N4SO Ken Brown Mobile, AL/EM50tk NorCal-20/5 watts/4 ele. beam N4SO at juno.com ++++++++++++++++++