Re: K3EXREF and Trimble Thunderbolts

Posted by k.igor on Apr 05, 2011; 5:57pm
URL: http://elecraft.85.s1.nabble.com/K3EXREF-and-Trimble-Thunderbolts-tp6242158p6243252.html



This is very valid question. Each method has advantages and disadvanages.

The GPS based reference needs antenna and ability to see satellites. If you lose satellites you enter so-called holdover mode, when your stability depends on local oscillator. In case of Trimble unit this will be free running OCXO - not too bad if the GPS will acquire satellites back in reasonable time. I am not familiar with the Trimble unit and how it handles holdover, I guess our friends with these units can tell us what happens to the frequency if they disconnect GPS antenna from the unit.

The LPRO is very stable frequency source and it does not require any antennas. For most of applications it will also give very good phase noise - probably not much worse than the OCXO in the Trimble unit. T he disadvantage of LPRO - limited life. New LPRO units were designed to service life of about 20 years. The units you buy on the web are used - you don't know how much life is left in it, it is quite possible it will fade in year or two if it was operated continuously for many years. It also can be little off frequency - the frequency of LPRO is adjustable (if I remember correctly).

73,

Igor, N1YX


----- Original Message -----
From: "G4ILO Julian" <[hidden email]>
To: [hidden email]
Sent: Tuesday, April 5, 2011 11:09:26 AM
Subject: Re: [Elecraft] K3EXREF and Trimble Thunderbolts

What are the advantages / disadvantages of this type of frequency standard
over the Efratom LPRO-101 which is a rubidium standard?

Julian, G4ILO

-----
Julian, G4ILO. K2 #392  K3 #222.
* G4ILO's Shack - http://www.g4ilo.com 
* KComm - http://www.g4ilo.com/kcomm.html 
* KTune - http://www.g4ilo.com/ktune.html 

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