Dave, The 49 MHz "1-ppm" oscillator is a TXCO, and it works well (0.5 ppm from 0 to 50 C). Originally we thought we would not be able to hit this target without adding firmware-based correction.
I did implement the firmware correction, but I wasn't happy with it, because it didn't provide much of an improvement beyond 0.5 ppm with all oscillators tested. What I found is that I had to create data for every 1 degree C, rather than every 5 degrees, in order to get to hit a more aggressive 0.25 ppm target. But the manufacturer of the TCXO had predicted that 5-degree data points would be sufficient for the algorithm, and that is what they supply with the oscillators. We could ask the for 1-degree data, but that would increase the cost (not to mention create five times as much data). It would also not be of much help to those who already had 1-ppm TCXOs installed. What we could do in a future release is provide a way for customers to manually generate and use 1-degree data. Call it "Method 4." It seems a bit onerous, but here's the idea: First, you'd put your K3 in the refrigerator long enough to get to 0C, or the desired low operating temp. Next, set the rig up with an accurate frequency counter connected to the output of the oscillator, and put the cover back on, or at least part of the way on (the freq counter cable has to come out at the back or side). Then, as the radio heats up, write down the oscillator frequencies for each 1-degree point. When it gets as hot as it's going to get due to ambient temperature, turn on a hot lamp or hair dryer and aim it at the top cover, about where the oscillator is. Continue heating and logging data until the desired max operating temperature is reached. You could then enter this info into a revised oscillator calibration data screen in K3 Utility. I'd have to add the firmware necessary to allow the oscillator to be updated continuously based on 1-degre data. This is a long answer to your question. It begs the further question, Would anyone bother? 73, Wayne N6KR On Jun 9, 2011, at 10:36 AM, Dave New, N8SBE wrote: > Wayne, > > What I guess I don't understand is why the TXCO functionality was > never > finished. Seems like that would help a number of accuracy/calibration > issues, and I bought the .5 ppm option expecting that it would be > useful. > > I'm disappointed in what appears to be a decision to abandon finishing > that project. > > On a related note, it wouldn't hurt to do something to fix the real > time > clock, so I don't have to keep syncing it with my laptop to keep it > reasonably on time. > > Thanks, > > -- Dave, N8SBE > >> -------- Original Message -------- >> Subject: Re: [Elecraft] [K3] K3EXREF K144REFLK and K144XV >> From: Wayne Burdick <[email protected]> >> Date: Thu, June 09, 2011 1:02 pm >> To: David Pratt <[email protected]> >> Cc: [email protected], Tim Taylor <[email protected]> >> >> >> I'm on the hook for this. I'll send out test code when it's ready. >> >> 73, >> Wayne >> N6KR >> >> On Jun 9, 2011, at 9:36 AM, David Pratt wrote: >> >>> Tim - My understanding is that the K3EXREF does not stabilise the >>> transverter offset. I believe this is planned in a future K3 >>> firmware >>> upgrade, but as far as I am aware this has not yet happened. >>> >>> 73 de David G4DMP >>> >>> In a recent message, Tim Taylor <[email protected]> writes >>>> So right now, the K3EXREF will stabilize the frequency of the basic >>>> radio; >>>> however, it will not stabilize the frequency of the K144XV. It is >>>> my >>>> understanding that the firmware for the K144XV is "in the que". >>> -- >>> + - - - - - - - - - - - - - - - - + >>> | David M Pratt, Kippax, Leeds. | >>> | Website: http://www.g4dmp.co.uk | >>> + - - - - - - - - - - - - - - - - + >>> >>> >>> >>> ______________________________________________________________ >>> 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 ______________________________________________________________ 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
