Posted by Mark n2qt on Apr 28, 2012; 3:59pm URL: http://elecraft.85.s1.nabble.com/K3-ANT-1-2-isolation-tp7500652p7509180.html
with isolation numbers like this perhaps there is hope for
duplex mode, with transmitting on one band with the
subrx enabled and listening on another??
Hopefully!
Mark n2qt
-----Original Message-----
From: Mark - G4AXX
Sent: Saturday, April 28, 2012 11:27 AM
To: [hidden email] Subject: Re: [Elecraft] K3 ANT 1-2 isolation
The isolation between ANT 1 and ANT 2 varies from -76dB at 1.8MHz to -46dB
at
50MHz.
This is measured with a signal generator, using the K3 S-meter, with ANT 2,
AUX RF and RX ANT IN terminated in 50 Ohms.
The isolation between AUX RF and ANT 1/2 is >95dB (1-30MHz), rising to -70dB
(52MHz).
This was measured with an N2PK VNA.
I have tried to dress the unscreened wires from ANT 1 & 2 to the ATU in a
way to minimise coupling, but the coupling is dominated by the capacitance
of relays K18 & K19.
Using ANT1/2 for Diversity reception means the receivers are never truly
independent. There is likely to be more coupling inside the K3 than can
usually be achieved by physical separation of the antennas.
Operating Diversity reception with the SUB RX fed from the AUX RF BNC input
is the way to go.