I was about to reply to an e-mail query but lost ALL the correspondence.

Dear ?

I hope the following suffices -

Agreed, an increase in efficiency from 2 percent to 14 percent does, in some
circumstances, corresponds to about 8.5 dB change in level.

But when, whatever the actual power output is when the efficiency is 2
percent, is increased by BY 14 percent it corresponds only to a 0.6 dB
change in level.

But it's hardly worth discussing. All ball-park stuff anyway. To answer
your other question would involve writing a book on the subject - at my
time of life? ;o)

Incidentally, the improvement in radiating efficiency due to exchanging a
BOTTOM loading coil with a top hat can be studied by downloading program
TOPHAT2. A mobile top hat nearly always wins but suffers from its mechanical
disadvantages.

Program LOADCOIL deals with a variable-height loading (sliding) coil to
maximise efficiency.

I do not have a program which covers a variable-height loading-coil plus top
hat for the simple reason that it would not be worth the extrordinary amount
of trouble of writing one. What's a few 1/10ths of a dB anyway?
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Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
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