[Elecraft] [K3] K3EXREF K144REFLK and K144XV

[Dave New, N8SBE]

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" <n8sbe at arrl.net>
> Date: Thu, June 09, 2011 2:51 pm
> To: "Wayne Burdick" <n6kr at elecraft.com>
> Cc: elecraft at mailman.qth.net, Tim Taylor <tim-taylor at comcast.net>
>
>
> 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 <n6kr at elecraft.com>
> > Date: Thu, June 09, 2011 2:08 pm
> > To: "Dave New, N8SBE" <n8sbe at arrl.net>
> > Cc: elecraft at mailman.qth.net, "Tim Taylor" <tim-taylor at comcast.net>,
> > "David Pratt" <david at g4dmp.fsnet.co.uk>
> >
> >
> > 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 <n6kr at elecraft.com>
> > >> Date: Thu, June 09, 2011 1:02 pm
> > >> To: David Pratt <david at g4dmp.fsnet.co.uk>
> > >> Cc: elecraft at mailman.qth.net, Tim Taylor <tim-taylor at comcast.net>
> > >>
> > >>
> > >> 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 <tim-taylor at comcast.net> 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 |
> > >>> + - - - - - - - - - - - - - - - - +
> > >>>
> > >>>
> > >>>
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