AI4QJ wrote:

As another poster said, there is very high noise at this frequency. The way
this radio works is to use the coil as both an antenna and the resonating
inductance in the tuned circuit. I have found that, in high noise
applications like this, often the best way to get a clear signal is to
off-tune the receiving antenna, for example, tuning the receiving circuit to
the frequency you need but using a shorter antenna. A 40m antenna often
works well for receiving 80m and 160m stations without all the noise. . .

Do you mean you can get a better signal/noise ratio with a 40 m antenna
on 80 or 160 than with a half wave 80 or 160 meter antenna? If so, what
do you suppose the mechanism is by which the shorter antenna
distinguishes between signal and noise?

I've seen cases where a receiver designed for use with a small whip
antenna became overloaded when connected to a decent antenna. Adding
attenuation or using a shorter antenna improved the S/N ratio because a
lot of the noise was due to intermod from the receiver overloading. I've
never seen this with a decent receiver, however.

Roy Lewallen, W7EL