Message text written by Bob Sutton
> The deterioration in the distortion products was alarming and very
similar for all three brands ... typically a 0.5dB (12W?) increase from the
nominal 100W pep power level resulted in an increase of 8-10dB in the
intermod "splatter" out the sides of a 2-tone test.<
That's about what I'd expect. Measured on an HP 8590, several "100W" HF
rigs including my FT-990 display very similar characteristics: the
higher-order IMDs increase very rapidly above about 80W PEP output, and
anything much above 7th-order is inevitably going to give rise to splatter.
Most VHF radios I've looked at over the years behave in the same way -- a
dramatic increase in high-order IMD for a small indicated increase in PEP,
much of which is going to consist of IMDs anyway.
>Perhaps technology has progressed since them <
The laws of physics aren't often repealed, unfortunately. That's why I'd
like to see a standard. How about always stating power in terms of the PEP
at which all IMDs above 7th-order are -60dB below one tone of two?
It's funny how irrational we are about power output. With the honourable
exception of the EME world, where 1.76dB would be very well worth having,
hands up all those who think that the difference between 100 and 150W on HF
is going to account for whether or not you get through the pile-up?
John Nelson
GW4FRX
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