>Yes, the 807 is more-or-less an 6L6 with different
>connections.
>
>Costas SV1XV

I'm not sure I agree with this.  My Wireless World valve data book from the 
late 1950s describes the 6L6 as an (audio) output beam tetrode rated for 300V 
on the anode, 200V  on the screen, and delivering about 6W output.

The same book quotes the 807 as accepting up to 600V on the anode, 250V on the 
screen and being able to deliver up to 40W RF at up to 60MHz.

I recall reading in the RSGB Bulletin of old-timer who ran 110W to a single 807 
using on-off keying and with 1kV on the anode.  He said the important thing was 
to keep the screen dissipation low.  I am not sure a 6L6 would do as well.

73,
John G3PAI