[Elecraft] [K3] TXCO

[Mike Harris]

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" <w3fpr at embarqmail.com>
To: <n5ge at n5ge.com>
Cc: "Elecraft" <elecraft at mailman.qth.net>
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