From ARRL's recent review:
"The differences are in the details. The
?9000D has three choices for roofing filter
bandwidth at 3, 6 and 15 kHz, while the
?7800 has two?6 and 15 kHz. The 3 kHz
roofing filter and the sharp MicroTune
preselector front-end account for the
?9000D?s 9 dB edge in third order dynamic
range at 5 kHz spacing (an impressive 98
dB at 14 MHz, the best we?ve ever seen!)."
Hmmm...I wonder if "impressive"
results are not also due to the fact that the
MicroTune preselector further attenuates
MDS by 9 dB beyond that measured
with Attenuator Off. The differences indeed
are "in the details". I wonder how Orion's
results would compare to "the best we've ever
seen" if another 15 dB of attenuation were
added to its front-end (to normalize MDS)?
Here are comparable data for
the FT-9000 (14 MHz, 500 Hz BW, Preamp
Off plus MicroTune) vs Orion (14 MHz, 500 Hz
BW, Preamp Off):
Radio MDS IMDDR3
FT-9000 -113 dBm 98 dB
Orion -128 dBm 92 dB
Even without MicroTune, the FT-9000
still has MDS 6 dB higher than Orion (both at
14 MHz, 500 Hz BW and Preamp Off) :
Radio MDS IMDDR3
FT-9000 -122 dBm 95 dB
Orion -128 dBm 92 dB
How would these compare if another 6 dB of
attenuation were added to Orion?
Normalizing for 500 Hz BW has long
been done in rig comparisons. Maybe it's time
to also consider normalizing for sensitivity
differences (i.e. MDS). After all, aren't we trying
to simulate rigs copying an identical weak DX
signal (i.e. same MDS) under QRM conditions?
73, Bill W4ZV
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