[time-nuts] KS-24361 EFC Error

Matthias Jelen Matthias.Jelen at gmx.de
Tue Aug 11 09:44:09 EDT 2015

Hello Time-Nuts,

I have a RFTG-U REF-0 / REF-1 pair here which seems to have a problem. 
The error LED of the REF-1 box stays on forever, and Ulrichs SW reports 
an EFC Error. After OCXO warmup, the EFC goes doen to it´s lower rail 
(-100 %) and stays there forever.

Indeed the 5 MHz Output from the OCXO is abt. 2 Hz of (compared to the 
10 MHz Output of the REF-0 which works OK). Tuning voltage to the OCXO 
is 0V.

During power up, the tuning voltage is abt. 3.1 V and the OCXO is abt 4 
Hz to low. During this time, the DIAG:OSC.EFC:REL? gives me something 
like 3.085 E+000 - so I guess this is abt. 3% of the tuning voltage.

Reference voltage output from the OCXO itself is abt. 6.1 V.

 From that I conclude that the tuning voltage range is from 0 to + 6 Volts.

When the tuning voltage drops from 3 V to 0 V, frequency goes up, but 
not high enough -2 Hz offset from 5 MHz remain.

This makes me think that the OCXO has a problem and is not reaching the 
5 MHz within it´s tuning range.

Bevor I heat up the big soldering iron to remove the OCXO, I wanted to 
ask if anybody else experienced this before and if anybody can confirm 
that tuning voltage range is indeed 0..6 Volt. If so, replacing the OCXO 
should cure the problem.



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