[Elecraft] KPA-1500: Gain Mod when FCC Lifts 15db Rule

[Edward R Cole]

A little more background for the FCC (USA) gain restriction for HF amplifiers:

I believe that was a result of wanting to stymie CB use of ham 
amplifiers using 5-15w drive.  15-dB for 1500w implies 47w min drive.

The LDMOS being used for 1200w on 2m only require 3-4w drive; that is 
26-dB gain!  Likely the devices chosen by Elecraft for their KPA1500 
have similar gain so they install attenuation into the drive path or 
change bias to lower gain (or both).  My guess once the schematic is 
available any non-USA ham can bypass the input to enable lower drive 
requirements.  A KX2 or KX3 ought to suffice.

Of course this would violate warrantee.

On a similar thought process, now that the KX3 is capable of 15w, I'm 
wondering if driving the KXPA100 harder than 8w will result in higher 
output?  Would it be safe to do?
I'm thinking 10w/100w.  The KXPA100 I have drives easily to 110w 
saturated with about 4-5w on 80-15m, but requires 8w to achieve 70-80w at 6m.

73, Ed - KL7UW
   http://www.kl7uw.com
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