[Elecraft] Diversity reception with two linked K3s

[Jerry Flanders]

It is possible to link two K3s together through the serial ports and 
synchronize their tuning using N8LP's LP-Bridge, a free program 
available from his telepostinc.com website.

I now have both my K3s lock-tuned together for rx diversity 
experiments. After setting the second K3's baud rate to 4800 with the 
K3 utility to match LP-Bridge, I connected it to LP-Bridge's "output 
com port #1" and pointed that port to match the physical com port the 
second K3 was connected to. I have two serial ports on this machine, 
with the other port servicing the "Master" K3.

The second K3 follows the first K3's bandswitching/tuning when I tune 
with the buttons/knob. It also acts as a tuned slave to WU2X's 
PowerSDR connected to LP-Bridge (see below) , so PowerSDR can be 
"master" to both K3s. Tuning reaction time is sightly delayed - maybe 
200-300 ms. Trying to tune the second K3 manually does not have any 
effect on either PowerSDR or the master K3, but it is immediately 
reset back to the master's freq.

Since LP-Bridge does not relay the mode/filter commands to the output 
port, I have to set these manually on the second K3. N8LP tells me 
that this may be changed in some future version of LP-Bridge.

I note there is a few Hz difference in the beat note between them on 
stations - I will get them aligned together more closely later. I use 
headphones with each radio in one earpiece, so I may not be bothered 
by minor differences. Much is yet to be learned.

I am also using WU2X's PowerSDR as a panadaptor (google LP-Pan 
panadaptor) in this setup, and have gotten used to actually tuning my 
master K3 with it - both in "click-tune" mode and conventional 
mousewheel fine tuning. The second K3 tracks the master perfectly 
when I tune them with PowerSDR. NOTE - the panadaptor is not required 
to link the two K3s - only LP-Bridge is required.

I have several antennas, so look forward to some Rx diversity 
experiments with this setup. I do not plan any transmit until I can 
verify safe RF levels on the other K3 or a method of disconnecting 
its antenna during tx.

Currently using LP-Bridge V0.9.82, WU2X PowrSDR V0.92, K3 FW Rev 2.38

Jerry W4UK