[Elecraft] Connecting to Sub-Rx IF

[Edward R. Cole]

I brought out a connection from the sub-Rx IF of my K3, today.  Not 
too hard once I figured out a couple things.  I am tapped into the IF 
at P86A (or W3).  This is the input to the Noise Blanker on the 
KRX3.  One caution is that +9vdc is present at this point so one must 
provide a .001 uF coupling capacitor to block the DC as this is 
subject to loading or shorting when you connect to the IF.  I used a 
small disc ceramic cap.

The cap feeds a run of RG-174 (100% shield Belden 7805) coaxial cable 
which I have placed two ferrite beads over the coax shield at the 
connection to the cap.  I bring the coax out a large hole in the 
KRX-3 shield where I added two windings thru a .37 inch toroid core 
for more decoupling.  The coax then runs to a panel-mount (UG-1094) 
BNC connector in the hole provided for the XV144 internal transverter 
(which I do not have).

This provides equal signal level as the the main-Rx IF to my 
LP-Pan's.  I will write up the installation with plenty of photos on 
my webpage for the Linrad Project:
http://www.kl7uw.com/LINRAD.htm

A big CAVEAT to anyone considering doing this:  Use anti-static mat, 
wrist-strap, and ground your tools and solder iron to the radio case 
before touching any circuitry.  This is best left to the experienced builder.


73, Ed - KL7UW, WD2XSH/45
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