[AMPS] IMDs

[Tom Rauch]

> > Are they dB below PEP (ARRL method), or dB below a single tone 
> > (commercial method)?
> 
> Below a single tone. I thought I had mentioned that in the posting.

Yes, I re-read the text and see where you did mention it. It is 
important to call attention to the fact you used "below one tone" 
values.

The ARRL uses below PEP, making everything look six dB better.

That because PEP is four times the single tone power level (not 
twice) in a two tone test.
 
So add six dB to the figures below, and that's what the ARRL 
would publish (and a few manufacturers).

Eimac uses dB below one tone, so their figures can be compared 
directly to yours. Other tube manufacturers use dB below PEP, but 
don't openly tell us. Everything they sell looks 6 dB better. IMD is 
like antenna tuner power ratings! You have to specifically ask about 
the test, or you'll get burnt.

> > > Power    3rd    5th    7th    9th    11th    13th    15th    17th 2.5W
> > >    -28    -29    -41    -47    -49    -53    -62 3.0W    -24    -30   
> > > -37    -48    -53    -53    -57    -64 4.0W    -16    -30    -35   
> > > -37    -43    -53    -58    -61
73, Tom W8JI
w8ji@contesting.com

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