Hello group, It's been many months since I've posted here, much less actually done something new with my K3. This topic has however piqued my interest. Just so I understand fully, am I right in assuming then that the following is correct:
1. Any reference oscillator operating at 10 MHz would work with the K3XREF? 2. All that's needed for this to work is the K3XREF, updated firmware, an accurate 10 MHz clock/oscillator, and a BNC cable? 3. Trimble Thunderbolt seems to be a good, cheap product to try. Any others that are > $100? What are the additional advantages of doing this other than knowing you've pretty much eliminated any frequency drift? 73 de James K2QI President UNARC/4U1UN On Tue, Apr 5, 2011 at 2:32 PM, Rich Heineck <[email protected]> wrote: > The K3EXREF uses the 10 MHz standard as it's time base to measure the K3's > TCXO and passes > an error value to the K3's MCU every few seconds. No TCXO frequency control > takes place, > thus no increase in phase noise. Frequency compensation is done in software > by > automatically updating the REF CAL function. A relatively simple mechanism > but effective :) > > For my installation, I'm using a Thunderbolt, an $11 active antenna from > Digi-Key, and a > 30' run of RG-6, which works nicely with the F connector on the Tbolt. > > 73, > Rich AC7MA > > On 4/5/2011 10:35 AM, Leigh L. Klotz Jr WA5ZNU wrote: >> ... >> The K3XREF product that Elecraft is developing is, to my understanding, an >> external disciplining interface for the TCXO in the K3. It's probably a >> frequency counter / microprocessor which reads the internal oscillator and >> the external 10 MHz reference, and when the internal oscillator doesn't >> produce the right number of cycles in 10 million of the external >> oscillator's cycles, it adjusts the voltage on the TCXO to bring it back >> into spec. But if you do this too often, you'll introduce phase noise into >> the K3 (think of it as FM-ing). Wayne N6KR has said it does this a few >> times a second an has achieved a trade off between accuracy and phase noise. >> (I presume he doesn't adjust during TX, for example.) >> >> I leave my K3 on most of the time, and I've found that it is seldom off more >> than +/- 3 Hz. But the K3XREF would let it off +/- 1Hz as soon as you turn >> it on, provided it's hooked up to your external reference. The actual >> received frequency is only valid for one mode and one filter, once you >> calibrate it, since when you shift modes or filters the offets of the >> various internal IF stages varies. (Keep that in mind if you use the K3 for >> the ARRL FMT.) >> >> Leigh/WA5ZNU ______________________________________________________________ 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
