> Tom said:
>>That's -40dB PEP
> (crummy ARRL method).<
> Referencing to PEP is an accepted professional method
> internationally, Tom, including at the ITU. And it has
> been for many years - probably before you were licenced.
> Certainly long before I was, but that's only 47 years ago.
Not for power tubes Peter. Not for the FCC. Not for Hams.
Eimac for years and years uses dB below one tone. If you
look at history Collins traditionally used dB below one tone
but snuck the change to PEP into the KWM-380 which made it
look somewhat acceptable when it was far worse than the
KWM-2 and stuff. If you pull an Eimac data sheet it is all
dB below one tone.
The ARRL changed about the same time as the KWM-380, which
is NOT a problem if people say when they are using dB PEP.
The problem is Hams grab an Eimac data sheet and read where
a tube is -35dB IM3, and assume it is the same as a radio
at -35dB IM3.
The problem is the radios are all at -35dB (or whatever)
PEP, not -35dB one tone of two. So the radio is either -29dB
compared to the tube, or the tube is -41dB if you compare it
to the radio and both are on even footing.
Some tube manufacturers even used dB PEP to pitch their
tubes and compared them to Eimac tubes speced at dB below
one tone. This gave their tubes a six dB false advantage,
and they started claiming their tubes that were actually
worse were cleaner.
dB PEP has certainly long been an acceptable method, no
problem there. The problem is when an industry or market
suddenly changes and people "forget" there are two methods,
one which was always standard use, and advertisers "forget"
to adjust or state they are using a different method.
73 Tom
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