I've been spending a lot of time looking at the Line Output of my K3 using the wonderful (and more remarkably, free) Spectrum Lab program. http://freenet-homepage.de/dl4yhf/spectra1.html
In so doing, I developed an alternate way to set the K3 (or other radio) Ref Osc. frequency if you have a computer and sound card (who doesn't these days). WWV and WWVH broadcast standard audio tones as part of NIST's family of standard frequencies. A table of these can be seen here: http://tf.nist.gov/stations/iform.html#stdf Method 2 of the Reference Cal procedure in the K3 manual uses the carrier of stations like WWV(H) as a reference, but works best with steady signals so that the amplitudes of the received audio and the monitor tone are similar. This is probably still the better method, but with today's propagation, at some locations this may be problematic. The following is an alternative that may be useful. If one sets their K3 to AM mode and one of the WWV(H) broadcast frequencies, e.g. 10.000000 MHz and looks at the K3 output with Spectrum Lab set to scan a range of say, 200 to 800 Hz, then during one of the time periods that a standard tone is broadcast, you will see a signal peak at that frequency on your computer screen. (This is a good check on the clock in your sound card.) With even a poor signal, Spectrum Lab will dig out the tone, making this work under dismal conditions. Now when you select either LSB or USB (normalize the DSP bandwidths in both modes) if the Reference Oscillator calibration is set correctly, you should see the peak at nearly* the same frequency on the Spectrum Lab display. If the calibration is wrong, then the response on one sideband will be offset from the AM case and the other sideband will offset in the opposite direction. By using MENU:CONF:REF CAL and dialing in the frequency while cycling through LSB, USB and AM the three peaks can be made to (nearly*) coincide. * While I'm not privy to all of the frequency manipulation that takes place as the DSP bandwidth is changed, I know that it's complicated and inexact, so "nearly" seems to be the best that I've seem. The "Shift" control setting does affect the beat note. This is generally inaudible, but on some frequencies, I've heard it by ear. This is true in CW too, so Method 2 carries the same caveat. Offered with no warranty. YMMV. Wes Stewart N7WS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
