Depending on why you want the accuracy, I think you could improve things by building a phase comparator to "listen" to the radio output frequency against a local reference. That would allow you to get much closer than using your ears as a phase detector. That should get you accuracy of a few % of 1Hz at your frequency you are measuring.
If you are really serious about accuracy, you can build a frequency reference based on the WWV transmissions that will get you to within 1 part per billion at 1MHz without too much trouble. There was a QEX article recently, which you can find on the web at http://www.arrl.org/files/file/QEX_Next_Issue/2015/Nov-Dec_2015/Magliacane.pdf . I'm sure that spending money on a GPS reference would be quicker, but less fun than building a project. If you go down that road, you'll be well on your way to winning frequency measuring contests! - Brendon KK6AYI On Sun, Dec 18, 2016 at 5:07 AM, Don Wilhelm <[email protected]> wrote: > Brian, > > The higher the WWV frequency, the possible percentage of error goes down. > One or two Hz is a smaller fraction of 20MHz than at 5MHz. > > In the K3, you are calibrating the reference (out of the synthesizer) > rather than calibrating the actual VFO frequency. The actual VFO frequency > is derived from and phase locked to that reference. > > 73, > Don W3FPR > > > On 12/18/2016 12:17 AM, Brian Denley wrote: > >> Fred, Don: >> I ask because I am curious. On any older receiver, calibration at 20 MHz >> would not guarantee cal below that ( or at any other frequency ). One >> could be 5 hz high at 30 MHz but 10 hz low at 7 MHz. Why is the K3 >> different? >> >> Brian Denley >> KB1VBF >> Sent from my iPad >> >> On Dec 17, 2016, at 3:43 PM, Fred Jensen <[email protected]> wrote: >>> >>> I guess it depends on how accurate you want your K3 frequency display to >>> be. I think AM-S will warp the frequency a tiny bit to sync the carrier so >>> that may not be the best mode. I'd also go as high as you can on WWV. >>> >>> Wayne suggested a method that is somewhere on the E-site which I used-- >>> >>> Use the highest WWV frequency that you can hear well. USB or LSB, WIDTH >>> to 500-800 Hz, SHIFT so can hear the carrier beat note [it will be very >>> low]. CONFIG-->REF CAL, wait for a tone-less minute and adjust REF CAL for >>> exact zero beat. You'll be counting the pulsations in the background noise >>> as you come up on zero beat. >>> >>> I got mine to about 10 seconds per pulsation on 20 MHz back when there >>> were sunspots. That's an accuracy of 0.1 Hz and everything below 20 MHz >>> will be at least that good. >>> >>> 73, >>> >>> Fred K6DGW >>> - Sparks NV DM09dn >>> >>> - Northern California Contest Club >>> - CU in the Cal QSO Party 7-8 Oct 2017 >>> - www.cqp.org >>> >>> On 12/16/2016 5:12 PM, Michael via Elecraft wrote: >>>> If I set my K3's VFO to WWV at 5.000000 MHz with AM-S on....and I adjust >>>> "REF CAL" to a number where >>>> my VFO's frequency readout is exact or near this number +/- maybe a >>>> Hertz >>>> or two. Is this an accurate way to calibrate my K3? >>>> >>>> It seems to be very accurate as far as I can tell. >>>> >>>> Has anyone used this method? >>>> >>>> Michael >>>> N2ZDB >>>> >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [email protected] >>> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] >> >> ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
