Rob NC0B:
>I would say for CW, 80 dB DR3 is adequate most of the time.
Certainly 85 dB is adequate on CW virtually all the time.
W8JI and I completely agree on this.
I am still mystified by RSGB's measurement
of the Sub-RX in Orion II. It shows 85 dB IMDDR3 at
1 kHz versus 96 dB for the Main Rx. 85 dB at 1 kHz
would be a *phenomenal* result for a 20 kHz roofing
filter if true. ARRL measured 67 dB at 2 kHz versus
95 dB for the Main, which is consistent with their
measurements of the original Orion. I wonder if
G3SJX may have made a transposition of his data
(table of close-in IMD on page 2 of the article).
For anyone who thinks IMD is not important,
they can hear it by tuning around with the Sub-RX
in the next CW contest and compare vs the Main-RX.
There is a HUGE difference. Orion's Sub-RX has IMD
performance in the same ballpark as rigs like the
IC-756PROIII (i.e. both use ~15 kHz roofing filters).
73, Bill W4ZV
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