Hello Graham,

Thanks for the encouragement.

I will add Opera 477 to my listening set up.
This can be done by either using a fourth software receiver in 
SDRConsole running on an Afedri SDR. However, lately I have been 
playing on NAVTEX 518 kHz with a 20 Euro RTL-SDR V3. This has been a 
revelation and it is about on par with the Afedri!

It is a bit deaf at LF, hence I am using a tuneable pre-amplifier 
preceded by a 530 kHz low pass filter. This way it becomes a decent 
receiver.

Just for fun, I will set it up for Opera 477 kHz and let it run 
overnight.

73,
Roelof, pa0rdt