[Elecraft] [K3] K3EXREF K144REFLK and K144XV

[Wayne Burdick]

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 |
>>> + - - - - - - - - - - - - - - - - +
>>>
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft at mailman.qth.net
>>>
>>> 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:Elecraft at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html