>I believe a number of people have commented that many of the transceivers
>available now still dominate the overall IMD performance when an amplifier
>is added.
This thread has got me interested. What should be the minimum acceptable
IMD spec for a transceiver? An amplifier, I think, will either pass
through the transceiver's IMD or make it worse.
I quickly scanned through the ARRL web site (members only section) and
found the IMD test charts for the FT1000MP and the TS2000. The TS2000
readings are both tabulated and graphed, while the FT1000MP results appear
to be only in graph format.
If I have read the charts correctly then the FT1000MP has better IMD
numbers than the TS2000 on 160, 80, and 30 meters. They have the same IMD
performance on 17 meters. The TS2000 has better IMD on 40, 20, 15, 12, and
10 meters.
The worst reading for the TS2000 is -27 dB on 160 meters, and the FT1000MP
worst case is -28 dB on 12 meters.
Assuming, for sake of argument, that -30 dB should be the minimum IMD
allowed, then the TS2000 does not meet specs only on 160 meters and the
FT1000MP does not meet specs on 20, 15, 12, and 10 meters.
Does IMD performance vary from model to model? Is poor IMD acceptable on
certain bands more than others (I doubt it)?
Will reducing the drive improve IMD significantly?
How do the IMD results show themselves in the real world, how far out will
the splatter be objectionable? Splatter is bad, but splatter at 10 KHz is
worse than splatter at 5 Khz.
--
Zyg AF4MP
Roswell GA USA
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