[Elecraft] KX3 AM breakthrough (&KX2)

[Philip Anderson]

Hi everyone,

I have been using a KX2 as my main rig for most of this year, it works 
very well although the receiver sometimes struggles a bit from my 
favorite portable location right next to the sea, where there's often a 
large amount of very strong signals.

Because of this, recent review comparisons of the KX2 with the KX3 
tempted me to buy a KX3 mostly for the extra receive performance. 
Unfortunately, when I tried the KX3 from my favorite portable location 
next to the sea yesterday, I had a problem with breakthrough of an AM 
broadcast station on 20m, the only way I could completely eliminate the 
problem was by turning on RX SHIFT, which unfortunately disables the 
roofing filter (a big reason for buying the KX3) and dual watch.

I understand from comments I have read that this issue is an inherent 
weakness of the direct conversion architecture, however - my KX2 never 
suffers from this problem.

So before surrendering to the possibility that I've spent $$$ on a 
larger KX2 with disabled dual watch ;) I thought I'd explore 
alternatives to using the RX SHIFT feature.

Since I've never had this problem with my KX2, and since that radio does 
not have the RX SHIFT feature, I'm assuming that for some hardware 
reason, the problem of AM broadcast breakthrough is not expected on the 
KX2.

Does anyone know what the difference between the two is? I suspect that 
the KX2 has a more severe high pass filter, in which case a 3Mhz high 
pass filter in the KX3 aerial lead might help sort out everything above 
top band.

Has anyone tried that?

Has anyone found any other solutions?

Phil G4PWO