[Elecraft] K3 receiver noise figure with KRX3 option

[Alan Ibbetson]

I want to parallel the receivers on my recently-acquired K2 with my K3. 
I have the KXV3A RX ANT option on my K3 and K160RX option on my K2. The 
"obvious" way to couple the two is with a 3dB hybrid but that will cost 
me 3dB degradation in noise figure on both receivers.

The KRX3 option in the K3 has to address the same problem and I'm 
wondering if there are any clever tricks I can copy. I am finding the 
schematics hard to follow but I can see a 3dB hybrid splitting the 
signal path in two. Where I'm struggling is in finding where the signal 
goes after leaving the hybrid. Is there a super low noise amplifier that 
I can't find on the diagrams to make up for the hybrid when the KXR3 is 
fitted? Or maybe perhaps the hybrid is there all the time whether the 
sub receiver option is installed or not and the design absorbs the loss 
into the overall noise figure?

Or is it all a lot cleverer than that?

Thanks,

Alan G3XAQ