[Amps] Question about SPE 1.3K-FA amplifier

[Bill Turner]

I notice the SPE 1.3K-FA amplifier is using a single LDMOS transistor
to achieve a peak of about 1500 watts output. I am wondering how they
do this and stay linear over the full 360 degree RF cycle. Normally
with a single-ended amplifier you have to either use a resonant tank
circuit to provide the "flywheel" effect, or run it class A. Solid
state amps normally use two devices in push pull but this amp does it
with only one. 

Since SPE apparently does not provide schematics or service manuals, I
am left curious as to how they achieve linearity.

Website:  http://www.spetlc.com/en/products/expert-13k-fa-uk.html

Does anyone know?

Educated guesses welcome. 

73, Bill W6WRT