Prototypes are working perfectly. We're getting ready for field testing. Wayne N6KR
---- http://www.elecraft.com On Dec 22, 2010, at 4:41 PM, [email protected] (Trevor Smithers) wrote: > Any news on the External Reference Option ? > > 73 > Trevor G0KTN > > -------- Original Message from Wayne N6KR dated 14 June 2010 -------- > > There appears to be more demand for this than we thought, so we're > looking into it again. > > Note that our planned external reference implementation would not > require an exact 49.380000-MHz reference oscillator signal. It also > doesn't require a pin-1 control voltage input on the TCXO module > itself, as suggested earlier. It should work with any existing K3 > TCXO, either +/- 5 or +/- 1 PPM. > > If you're interested, here are the details: > > A new REF-lock module would be designed that plugs into the small 8- > pin connector near the top of the KREF3 PCB. The user's 10-MHz > reference signal would be routed from the rear panel to the TMP > connector on the KRE3 (this connector faces forward, into the DSP/ > front panel area). > > A microcontroller on the REF-lock module would be clocked by the 10- > MHz reference. If the signal were present, the microcontroller would > continuously measure (and average) the frequency of the 49.38 MHz > oscillator, obtaining a value to the nearest 1 Hz. Hysteresis would be > applied to prevent "hunting," so the actual accuracy spec would > probably be +/- 2 Hz. This translates to about +/- 1 Hz in operating > frequency on 20 m. > > Approximately once per second, the module would report the actual > reference frequency to the K3's main MCU via a slow digital data line > (labeled "100HZ" on the RF and KREF3 schematics). The main MCU would > use this to calibrate the REF CAL value normally entered by the user. > There would be no noticeable impact on performance. > > If the 10 MHz external signal were not present, the user's normal REF > CAL value would be used. > > Let me know if you have thoughts on this implementation. > > 73, > Wayne > N6KR > ______________________________________________________________ > 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 ______________________________________________________________ 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
