Geez, I gotta quit relying on my memory. From the Dallas datasheet: The output is accurate to ±2ppm (±1 min/yr) from 0°C to +40°C and to ±7.5ppm (±4 min/year) from -40°C to 0°C and from +40°C to +85°C.
Not exactly .5 ppm, but this is for a different application (RTC) than what we were discussing. Beats our current ±30ppm on our existing time-of-day design, which works out to ±80 seconds/month. I'd certainly be happy if the K3 clock would stay within ±1 min/yr... 73, -- Dave, N8SBE > -------- Original Message -------- > Subject: Re: [Elecraft] [K3] K3EXREF K144REFLK and K144XV > From: "Dave New, N8SBE" <[email protected]> > Date: Thu, June 09, 2011 2:51 pm > To: "Wayne Burdick" <[email protected]> > Cc: [email protected], Tim Taylor <[email protected]> > > > Sorry, Seiko is the RTC -- google for S35390A_E.pdf > > Dallas (Maxim) is the TXCO supplier -- google for DS32kHz-DS32KHZS.pdf > > 73, > > -- Dave, N8SBE > > > -------- Original Message -------- > > Subject: Re: [Elecraft] [K3] K3EXREF K144REFLK and K144XV > > From: Wayne Burdick <[email protected]> > > Date: Thu, June 09, 2011 2:08 pm > > To: "Dave New, N8SBE" <[email protected]> > > Cc: [email protected], "Tim Taylor" <[email protected]>, > > "David Pratt" <[email protected]> > > > > > > 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 ______________________________________________________________ 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
