[Amps] class "A" RF amp question

[kenw2dtc]

Bob said:
"In your situation however my guess is the amplifier is not your problem but 
your exciter.  (As I assume you haven't modified your AL-1200 for plate 
modulation.)  You are clipping in the exciter when trying to drive your amp 
to higher power."

*******In the case of my AL-1200, I drive it with a Viking II.  My viking II 
is capable of 100% modulation at the 100 watt carrier level.  I have 
modified my Viking II to produce variable power and when the carrier power 
out is around 20 watts of 100% plate modulation, I look at both outputs 
(Viking II and AL-1200) and the pattern with sign wave modulation is pure. 
When I increase the 100% modulated Viking II and the amp carrier output goes 
above 380 watts, the modulation peaks start to flattop.  So in this case the 
exciter is not clipping.

Bob said:
"In Class A to answer your question, you would need to dissipate every bit 
of the PEP power level you are looking to put out in resting condition."
*******Do I understand that in my original example  (375 watt carrier, 1500 
watt pep) a tube in class "A" would only require a plate dissipation of 1500 
watts?  Implied in your answer is the thought that a 1500 watt PEP sideband 
signal would have the same class "A" dissipation requirement as a 1500 watt 
AM signal.  Help me out here.
73,
Ken W2DTC