G'day, Don beat me to this. However, I would like to add that the calibration of the TXCO is not a one off event. When I checked the calibration after a years worth of burn in I had to adjust the TXCO lf by about 50Hz. How much this translates into a dial error I've no idea, I've not bothered checking the frequency plan.
At an Intelsat Std B. Earth station I used to drive we had to keep our TX carriers better than 100Hz at 6GHz. The double ovened reference oscillators used to phase lock the SHF oscillators for the up-converters needed a trim up once a month. Regards, Mike VP8NO ----- Original Message ----- From: "Don Wilhelm" <[email protected]> To: <[email protected]> Cc: "Elecraft" <[email protected]> Sent: Monday, October 26, 2009 10:27 AM Subject: Re: [Elecraft] Re? K3 TXCO >I see that we are mixing terms in this thread. *Stability* and > *Accuracy* are two different things, and one does not imply the > other. > Those expecting better *accuracy* with the addition of software > compensation may be dissapointed (read on for more info). > > The high stability TCXO will not necessarily provide better > *accuracy* > than the standard TCXO, and method 3 will also not necessarily > provide > better accuracy. Method 3 will only provide tighter control over > temperature excursions. > > Accuracy is the ability to hit the target in the center of the > bullseye. Method 2 will provide accuracy just as close as Method > 3, but > Method 2 lacks the temperature compensation part. > > Stability is the ability to hit the target at the *same* place all > the > time - even though that may be far from the bullseye. And that is > the > part that will be improved with the software temperature > compensation. > > What the high stability TCXO offers is *stability* over a > temperature > range. If your K3 is never subjected to great temperature > excursions, > there may be little or no difference between the 2 Elecraft TCXO > offerings (yes, both are TCXOs, but one is spec'ed at 1% while the > other > is spec'ed at 5% by the TCXO manufacturer). The 1% spec'ed TCXO > was to > provide an overall 0.5% stability over temperature for the entire > K3. > > The high stability TCXO already provides the K3 with its > advertised 0.5% > stability, so what Wayne and Eric envisioned as needing software > compensation to provide the 0.5% stability 'does the deed' even > without > that compensation. But Wayne has stepped up to the plate and > offered a > software compensated stability of up to twice the specified > value - so > just wait a while. You have all that was advertised already, but > it > will get better than that if one is patient. > > 73, > Don W3FPR ______________________________________________________________ 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
