Posted by
Bob-270 on
Oct 30, 2011; 5:11am
URL: http://elecraft.85.s1.nabble.com/New-K3EXREF-results-tp6944433p6944890.html
Hi Matt,
I'm in Ohio and waiting for the storm to pass and roads to be cleared before going back to NJ so do not have the hard data available but I ran checks too. In my case the reference is an external Trimble Thunderbolt and I also saw shifts in the same range. Even if the first few hours are ignored, for warmup purposes, the shift was in excess of 50HZ. Your two cases indicate 81 & 85 HZ. If this is only the change in the reference oscillator it seems to be over the 1 PPM spec. However I was never sure if I was accounting for all error sources in watching this oscillator correction. The +/- 2 HZ locking error at 10MHZ would be +/-10 HZ at 50MHZ alone. I only used the values that were shown when the Trimble Thunderbolt was in disciplined mode.
Hopefully someone will comment and point out the errors in my thinking. Even if over the 1 PPM spec it is still the most stable and accurate receiver I've ever owned. The temperature compensation data is not being used as far as I know and I'm not close to the .5 PPM given as typical.
73,
Bob
K2TK ex KN2TKR (1956) & K2TKR
--- On Sat, 10/29/11, Matt Zilmer <
[hidden email]> wrote:
From: Matt Zilmer <
[hidden email]>
Subject: Re: [Elecraft] New K3EXREF results
To: "Mark Goecke" <
[hidden email]>
Cc:
[hidden email]
Date: Saturday, October 29, 2011, 5:54 PM
Results seem to be different for every TCXO. My REF*CAL starts about
around .693 and settles to .778 after a couple hours. I borrowed a
Rubidium clock from work and got nearly identical results. The only
difference was freq source, so the chracteristics must be K3-specific.
Another K3 owner and I ran it on his (#35xx-something) and his started
at .717 and settled out at .798. Same basic trends all around.
I'm also using the Trimble TB here; it's been active for ~six months
and results are always the same. The K3's resolution is still +/- 1
Hz, but now you know your rig uses the right ref osc frequency.
The REF*CAL value shown is the compensation for the external freq
reference. I'm not sure how Wayne calculates what's shown; maybe
he'll publish his secret sauce recipe...
73,
matt W6NIA
On Sat, 29 Oct 2011 16:38:41 -0500, you wrote:
>I just completed the install of my K3EXREF, and am feeding the 10MHZ reference from a Trimble Thunderbolt.
>
>After a couple of hours of warm up and settling out my reference osc is reading 49.379.945. I have the OXCO and was expecting to have better results that are closer to 49.380.000.
>
>Are my expectations unrealistic? Any suggestions?
>
>Mark Goecke KC5VF
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