[Elecraft] Calibrating KTCXO3 with the XG3

[Matt Zilmer]

Typically, the Trimble Thunderbolt GPSDO 10 MHZ reference exceeds
+/-100 PPT.  Not sure of the statistics, but that's the high end of
the range Lady Heather reports.  This GPSDO outputs a slightly
distorted sine wave at around 8 dBm, which is within the K3's rated
input range.  I just leave mine connected full-time.

73,
matt W6NIA

On Wed, 30 Apr 2014 09:25:02 -0400, you wrote:

>Slava,
>
>Most external reference sources have an output of +10 dBm or somewhere 
>around that level.
>It is not a matter of simply calibrating, the external reference is 
>intended to be connected continuously.
>Yes, there is a data table created that can be used when the reference 
>is not present.
>
>I really can't answer about the level of the XG3, but I am certain the 
>frequency accuracy it is not as tight as a real external reference - 
>rubidium standard or GPS disiplined oscillator.  The spec for the XG3 is 
>+/- 50 ppm while an external reference is typically stated in parts per 
>billion.
>
>73,
>Don W3FPR
>
>On 4/29/2014 11:18 PM, Slava Baytalskiy wrote:
>> Hello again, everyone!
>> I just installed the K3EXREF board in my K3 and i also have the KTCXO3 unit in there from before.
>> The idea was to use the XG3 as the external 10 MHz reference for calibration.
>> I wasn't thrilled with the accuracy of the zero-beat method that i was using (or rather i wasn't thrilled with MY accuracy).
>> I think i did the procedure correctly: went to REF CAL menu, enabled the K3EXREF, hooked up the BNC cable, the asterisk started flashing, the frequency changed (clearly the zero-beat i did before wasn't correct).
>> My only question is about the output level of the XG3: i used the zero dBm. But the calibration procedure mentioned that the reference signal should be between +4 dBm and something else (higher).
>> XG3 doesn't seem to go that high though. Is that ok? Using zero dBm for this?
>>
>>
>
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Matt Zilmer, W6NIA
www.elecraft.com
831-763-4211  x129