ATS25X2 MW breakthrough on the Tropical band

[alpard]

I got this radio recently, and it seems reasonably working ok above 6 Mhz.  But the tropical band 4 -6 Mhz suffers from severe MW intermodulation and breakthrough making impossible hear the weak DX signals.  It is more severe when longwire is connected to the radio.  I must increase the attenuator for the MW breakthrough signals disappear, but then total sensitivity also drops, which makes the DX signals disappear too.

What would be best way to tackle this problem?  I am thinking of getting some sort of balun.  But what about using loop antenna?
I had this problem before even with more expensive radios and the Wellbrook loops and MLA30 too.

[Charlie_Dont_Surf]

You could still have this problem even when using a loop, as you have noted this happening with a Wellbrook and MLA-30.

A more appropriate solution requires attenuating the MW signals while not attenuating the tropical bands. This is a job of a high-pass filter between the antenna and the receiver.

[alpard]

Yes, great point.  In the past, i had to put on the attenuator 10 to 20 dB when using those amplified loops not to overload the receiver.  It was more prone to overloading with the SDRs.

How about baluns?  Could they help the 4-5 Mhz MW breakthrough signals at nights?  I am using just whip antenna and wires too, but thinking of getting MLA30 again, or a KW-108 Active Loop. 

[Charlie_Dont_Surf]

A balun might help only if it has a sufficiently high minimum operating frequency, but even then I would expect a high-pass filter to perform better.

[alpard]

Found a 9:1 balun and linked between the longwire and ATS25X2, and using AGC combined with attenuator adjustment, it seems be working ok now.  The MW break-in were all stopped.  Only thing is there is no south or central american propagation into europe these days on the tropical bands.  I could hear only strong chinese signals.

[Charlie_Dont_Surf]

I'm glad it is working.