Don't use such an antenna with the compact SW receivers :

their antenna input is already high impedance.

Just used any length of wire that is NOT resonant at any frequency you want to listen to.

edit : with the simple wire end to the antenna input of the receiver, 'resonant' means a quarter wavelength (or an odd multiple). In practice, just use a random length !

I feel that the problem is the line. For good results, take a roll of bifilar wire

(sold as 'HIFI speaker wire' nowadays), tear apart the two wires for a few meters, do a knot to stop the tearing apart, and use the remaining part as a transmission downline to your receiver. The two wires made apart are a doublet that should be drawn horizontally and at right angle with the feedline to get the least noise. The total length of the original roll should not be ~~a resonant length~~ an odd multiple of a quater of a wavelength for any frequency of interest.