Hi Wes I am measuring the TX carrier frequency through an attenuator then to the frequency counter which is locked to the Rubidium. However, I dont know how this figures into what you are saying, but our club K3's are spot on.
Since there is possibility of improving the accuracy the external reference will be a waste of money and time for most us. John --- On Tue, 11/17/09, Wes Stewart <n...@yahoo.com> wrote: > From: Wes Stewart <n...@yahoo.com> > Subject: Re: [Elecraft] K3 frequency accuracy versus displayed precision > To: elecraft@mailman.qth.net, "juergen piezo" <plebia...@yahoo.com> > Date: Tuesday, November 17, 2009, 6:15 AM > Guys, > > I've mentioned this caviet before: > > http://n2.nabble.com/Ref-Osc-Cal-Method-4-td2595451.html#a2595451 > > The way the K3 implements the passband shift, the same > signal, with the same VFO setting, will have a different > audio beat note if the SHIFT control is changed. * > > So your calibrations with your atomic standards are no > better than the delta F that takes place when you vary the > shift control. > > If you want to measure frequency with the K3 BW and SHIFT > *always* set to the same values then OK. However, > calibrating at 50Hz BW and normalized SHIFT and then > changing to SSB bandwidths and declaring that some stations > are "on frequency" and others aren't is > stretching it. > > * I've discussed this > with Wayne and it's considered IP. > > Wes > N7WS > > --- On Tue, 11/17/09, juergen piezo > <plebia...@yahoo.com> wrote: > > From: juergen piezo <plebia...@yahoo.com> > Subject: Re: [Elecraft] K3 frequency accuracy versus > displayed precision > To: elecraft@mailman.qth.net > Date: Tuesday, November 17, 2009, 12:53 AM > > > Hi Paul > > I find the same thing, I have checked the clubs K3's > against a rubidium standard that was calibrated to a cesium > standard. The K3 is spot on, the only limitation > being its 1hz calibration step limit for the TCXO. I > wonder what use the yet to be released external standard > interface will be when we can only adjust the > TCXO in 1 hz steps. > > Its amazing how far off frequency most stations are > when you use a radio thats dead on, the typical average > being 40 to 80hz off. The > K3 sounds so good on RX these days, its easy to pick > stations that are off frequency by even a few HZ. The radios > that I have found to be consistently on frequency are the > IC7700 and IC7800. > > The SSB stations that impress me the most for being on > frequency are the different Aeronautical control towers. > These control towers have such excellent audio quality and > they are always spot on frequency. Its a shame that > more ham stations cant sound so professional and clear like > these aeronautical SSB stations. I have always wondered what > brand of transmitter they use? The excessive bass and > ESSB audio that we hear so often just sounds so > awful in comparison. Excessive bass and ESSB is just not > good audio for SSB use. (I dont want to start a SSB debate!) > but ESSB bassy audio sucks in comparison to these commercial > SSB stations! > > John > > > --- On Mon, 11/16/09, Paul Kirley <pkir...@fuse.net> wrote: > > > From: Paul Kirley <pkir...@fuse.net> > > Subject: [Elecraft] K3 frequency accuracy versus > displayed precision > > To: elecraft@mailman.qth.net > > Date: Monday, November 16, 2009, 6:28 PM > > The K3 is capable of displaying > > frequencies to 1 Hz. It can > > be calibrated to somewhat less than 1 Hz against WWV > > (method 2). > > > > Because I wanted to see if my K3 serial 1322 was > capable > > of > > measuring frequency to its displayed precision, I > decided > > to > > attempt the November 11/12 ARRL Frequency Measuring > Test. > > > > I warmed up my K3 for about two hours because--even > with > > the > > optional > TCXO--my K3 drifts almost 0.1 ppm per degree > > Centigrade > > from 25C to 30C, the latter part of its warmup range > this > > time > > of year at my QTH. (0.1 ppm is almost 1 Hz on > 40 > > meters.) > > > > Then I carefully used method 2 to calibrate against 10 > MHz > > WWV, > > checking after exiting REF CAL by tuning across WWV on > CW > > with > > SPOT activated to see that the beat notes were similar > on > > each > > side of zero beat for 1 and 2 Hz off frequency. > (A > > lack of > > similarity indicates that a small tweak of REF CAL is > > needed.) > > Tuning past WWV's carrier on CW with SPOT enabled > also > > provides > > practice for the real thing. > > > > When W1AW (and each of the other FMT stations) began > its > > call-up, > > I tuned its frequency to be centered in the passband > with > > the DSP > > set at 50 Hz bandwidth. When the > long dashes began, I > > turned on > > SPOT and zero-beated against the sidetone with 1 Hz > fine > > tuning. > > > > After recording the result, I moved on to the other > > frequencies > > and stations that had been specified in the ARRL FMT > > announcement. I was able to copy and measure 4 > of the > > 5 tests, > > with one station on one frequency being inaudible at > my > > QTH. > > > > Result: my K3 was within 1 Hz on all 4 readings, > that > > is, its > > accuracy matched its displayed precision--after warmup > and > > careful calibration. > > > > 73, Paul W8TM > > > > > > > > ______________________________________________________________ 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
