[Elecraft] Differences Between K4 Models

[Mister Mike]

 Can anybody please tell me what are the differences between the K4-F, K4D-F and the K4HD?   I looked on the web site and I was unable to find a comparison chart or anything more than purchasing information.

I currently have a K3 with many of the options, including the sub-receiver.  I am just curious what the K4 has to offer me.  Is there some comparison chart somewhere to show what the advantages are for me to buy a newer K4?  I am sure others would like to know too.

Than again, I am not an avid DXer or rabid contester.  I have been licensed for over 50 years and my operating patterns are pretty casual.

73,

Michael, W1RC
Marblehead Massachusetts.