[Elecraft] KREF-EXT Option

[SM6TUW]

Geoff,

I have not heard of any hardware from Elecraft yet.
In the meantimeI have been thinking on a possible solution to play with:

The K3 is ready for this option as can be seen from the circuid diagram.
 J4 provides all signals for a PLL  module (including 5V supply)while J3 on
the back panel picks up an external reference.
A syntheiziser built around f.ex ADF 4001( it is also used in the K3
synth) for locking the VCXO Z1 (49.380 MHz) to an external 10MHz is simple
in design.
For experiment with the ADF4001 it can be  programmed via a serial bus
connected to your computers parallell port. Analog Devices provides
programs and descriptions for this.

http://www.analog.com/Analog_Root/static/techSupport/designTools/evaluationBoards/downloadSoftware.html
Download Integer-N Software (ADF411X, ADF421X)

Evaluation board description:

http://www.analog.com/Analog_Root/static/techSupport/designTools/evaluationBoards/downloads/EVAL-ADF4001EB2_D.pdf

They also provide free loopfilter simulation software: ADIsimPLL Version
3.1

http://www.analog.com/static/imported-files/data_sheets/ADF4001.pdf

One approach after evaluation for a completely built in module is a EEPROM
for the PLL programming.
At power on the EEPROM programs  the PLL

Does anybody know the use of the "100Hz" P4 pin #1 ?

73
Jan ,  SM6TUW