[Elecraft] [K3] K3EXREF K144REFLK and K144XV

[Tim Taylor]

Hello,

I have a K3 with the K3EXREF, K144REFLK and K144XV.

 

Let me start by saying that the K3EXREF performs as described. It keeps the
K3 tuned to a frequency within about plus/minus 2 Hz. However, I don't think
it operates the way I thought. I initially thought that the K3EXREF adjusted
the actual 49 MHz reference frequency to stabilize it to an external
reference. After some testing, it appears that the 49 MHz reference
frequency from the oscillator is never changed by the K3EXREF. It appears
that the offset between the 49 MHz actual frequency and the 10 MHz reference
is compensated for in firmware. I have monitored the 49 MHz reference and it
continues to drift like it always has. At the same time, the tuned frequency
of the K3 stays within 2 Hz of the actual frequency.

 

The reason for the research was the continued inaccuracy of the K144XV
frequency after the installation of both the KEXREF and the K144REFLK. The
K144REFLK does lock the LO of the K144XV to the 49 MHz reference. It reduces
the "large" uncompensated drift of the K144XV down to between .5 and 1 PPM.
That is, it will drift in the neighborhood of 100 Hz AFTER warmup. This
appears to follow the spec of the 49 MHz reference oscillator. This DOES NOT
track the K3EXREF compensated stability. I would have expected the K144XV to
stay within about plus/minus 6 Hz when stabilized to the K3EXREF.

 

I called tech support and they seemed to confirm my analysis. The K3EXREF
only works from 160 to 6 meters. The firmware has not been written to have
it work with the K144XV. 

 

So right now, the K3EXREF will stabilize the frequency of the basic radio;
however, it will not stabilize the frequency of the K144XV. It is my
understanding that the firmware for the K144XV is "in the que".

 

73,

Tim K8XS