Just tune by the ear first (so that you know the transmission
is where you are looking for it) and then use the cable. Even with the cable in you can probably still listen to the sound via a speaker (on the radio
, or on the laptop). You will not have any problem tuning by the ear - it sounds like a fax (if you are old enough to remember what fax was).
If you are on the right frequency @ the right time and there is nothing, then go on to the next frequency and check there. Also - make sure you are switched on the USB / LSB or whatever is used in RSA.
We had no problem receiving there but it was a while ago.
WARNING: on at least one occasion we received wrong chart (bad date ...) and on another day there was nothing - all this during only a 2 weeks' of the passage