Dan, The K3EXREF controls the TCXO-3 to maintain a near zero offset compared with an external frequency reference. The K3 synthesizers are still referenced to the TCXO-3 all the time. So during the interval between frequency corrections, roughly every four seconds, the radio frequency is controlled by the TCXO-3. So frequency drift rate is not affected by the K3EXREF during this interval and only periodically corrected.
But this does keep the TCXO within 0.05 ppm vs 0.5 ppm. I was a beta tester and you can see my test results here: http://www.kl7uw.com/K3EXREF.htm The largest error observed was +2.5 Hz on 6m. ------------------------------ Message: 29 Date: Fri, 20 May 2011 08:58:55 -0700 (PDT) From: Dan AE9K <[email protected]> Subject: Re: [Elecraft] Installed K3EXREF To: [email protected] Message-ID: <[email protected]> Content-Type: text/plain; charset=us-ascii This may be a naive question but... If the K3EXREF keeps the K3's reference oscillator within 2 Hz, then what value is there in using the K3EXREF in conjunction with the KTCXO3 instead of just the native K3 oscillator? K3EXREF: 2 Hz error @ 14 MHz : 0.1 ppm K3TCXO3: 7 Hz error @ 14 MHz : 0.5 ppm Is the stability in ppm an instantaneous measurement of random error and not a measurement potential drift over some time delta? If this is true then using the K3EXREF alone presumably would exhibit the 5 ppm error of the native oscillator in the 4 to 8 second gaps between K3EXREF syncs. This would make the case for replacing the native oscillator with the K3TCXO3. If the stability is measured over time, however, then the K3EXREF and native oscillator would appear to be sufficient since oscillator drift is insignificant in the 4 to 8 second time span. Just curious. Dan AE9K 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-testing*, 3400-? DUBUS Magazine USA Rep [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
