Chinese receiver

This RX is called the K3.  This is not to be confused with the Elecraft K3. Certainly I was confused!  

It is available from AliExpress at about £60.  There seem to be a lot of these low cost Chinese receivers about.

500kHz with the Elecraft K3

On the Elecraft website I see there is an article showing how to use the K3 transceiver on 500kHz. The K3 will receive on 500kHz but needs an external PA (described) to get around 25W output. See http://www.elecraft.com/TechNotes/k3qtx_v2_pa3cw.pdf