RE LO noise measurements - Note that the Sherwood
measurements are not very consistent for the spacing used to
measure the LO phase noise:
Orion (II) 10kHz
Corsair 4kHz
Omni VI+ 20kHz
It's really too bad Bob didn't pick something in the range of
3-5 kHz as the standard spacing for the phase noise
measurement tests for all of the radios he tests. With the
test spacing all over the place it is hard to make any direct
comparisons between radios for LO phase noise performance.
Duane
N9DG
--- Bill Tippett <btippett@alum.mit.edu> wrote:
>
>
> 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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>
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