More data from:
http://www.sherweng.com/table.html
Sherwood has been making these measurements
consistently over many years:
Transceiver 10 kHz LO Noise IMD 20 kHz IMD 2 kHz
Orion -130 96 93
Corsair -132 93 79 (@ 3 kHz)
Omni VI+ -137 97 80
where LO Noise = Phase Noise
Again, I would expect an properly modified Omni VI to
have equivalent IMD performance as Orion at 2 kHz.
Here's another comparison by Inrad of Omni's
IMD using stock, 600 and 2400 Hz roofing filters:
http://www.qth.com/inrad/kits.htm#tentec
Spacing OEM 600 Hz filter 2400Hz filter
2 kHz 79 dB 94 dB 85.5 dB
5 kHz 82.5 97 95.5
10 kHz 86.5 98 96.5
20 kHz 95 97.5 97.5
These measurements cannot necessarily be
compared directly (i.e. RSGB vs Sherwood vs Inrad)
because they use different spacings, measurement
methodologies, equipment and testers. However,
they are probably internally consistent within normal
sample and measurement errors. From what I see
and know about the Inrad mod, I would probably
choose a 600 Hz Inrad modified Omni over the
Corsair for CW operation. Remember however
that the 600 Hz filter will not be inline when you use
Omni on SSB!
73, Bill W4ZV
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