[Elecraft] K3 External Reference input

[Philip Theis]

I am too.
Back in April Wayne said:

On Apr 29, 2007, at 3:20 AM, Bryan wrote: 

> Hi Wayne, 
> 
> If you use the external 10Mhz signal, does this mean that you don't 
> need the TCXO ? 

Even the standard K3 comes with a TCXO, so you'll always have one. 

The external reference option, when plugged in, will work with the TCXO. 

Note that the external reference module is not completed and may not be 
available at time of first shipments. But it'll be easy to install 
yourself once it arrives. Pricing hasn't been set. 

73, 
Wayne 
N6KR

Now that I have the K3 I'd like to connect it to my GPS Spectracom.
73,
Phil K3(352)TUF


-----Original Message-----
From: Paul Christensen [mailto:w9ac at arrl.net] 
Sent: Friday, February 22, 2008 8:24 PM
To: Philip Theis; elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 External Reference input

> Is there interest among the group for the necessary parts to input a
> disciplined 10MHz signal to control frequency?  We all know there is a 
> place
> holder on the back panel, but Gary just told me there were no plans.

I'm really hoping for this option.  I use a Hewlett-Packard 58540A GPSDO for

use with my IC-7800.  Long-term accuracy when GPS-locked is typically 1E-12.

That's essentially the same accuracy as the atomic cesium beam standards 
used on board the GPS satellites.

Most GPSDOs are not known for their ultra-high phase noise performance. 
Still, the SC-cut OCXOs as used in the HP Z3801A, HP Z3816A, and HP 58540A 
units are typically -145 dBc/Hz @ 1kHz offset.  On the used market, expect 
to pay USD $300-$800.  However, there is one relatively new, compact GPSDO 
from Jackson Labs that has hit the market and offers excellent phase noise 
performance for a GPSDO.:

http://www.jackson-labs.com/docs/Fury_Flyer.pdf

Even better phase noise performance (e.g., -165 dBc/Hz @ 1 kHz) can be had 
through the use of non-GPS-disciplined OCXOs.  For example, Wenzel makes 
highly accurate OCXOs with phase noise specs that are typically 0-15 dB 
better than the GPSDO types.

http://www.wenzel.com/pdffiles1/Oscillators/Comp.pdf

With either of these types, one simply connects the output of the OCXO to 
the 10MHz reference input on the transceiver with one cable.  The OCXO is 
powered from a low-voltage DC power source.  Although the K3 may not be 
capable of resolving to 1E-12 accuracy, you can be rest assured that when 
using either of these oscillator types that your signal will be the new 
frequency standard on the bands.

Paul, W9AC