--- Bill Tippett <btippett@alum.mit.edu> wrote:
> Corsair's measurements were done long ago before Rob had
> standardized on his current 10 kHz for phase
> noise and 2 kHz for IMD.
I will stick by my wish to see it standardized at something
under 5kHz, much for the same reason as wide spaced IMD
(>5kHz) measurements don't tell the story for real world
performance in the IMD dimension.
> Also, Orion's phase
> noise does not degrade appreciably at closer
> spacings compared to Omni. (see figure 2-b on
> page 5 below. I suspect Corsair also degrades
> more at very close spacings than Omni but do
> not have any measurements.
I highly doubt that is the case. I suspect that the Corsair
holds up better as you get closer. From what I can tell the
first radio that can truly match (I think may even exceed) a
non synthesized LO for phase noise performance is the Orion.
The big thing that I see with the Omni VI(+) phase noise plot
in the QST review(s) is that it is somewhat "spikey" I really
doubt that the Corsair (or any other PTO/Xtal LO radio) would
do that. Unfortunately the ARRL made no attempt to measure
phase noise of the Corsair II when they reviewed it in 1987.
That said I don't think that the measurements of the TX phase
noise that they started making a few years later necessarily
reflects how the RX performs for that parameter either.
One big flaw of the Omni VI that I have (Oct 1992 vintage -
no option upgrades) is that it is full of spurs on 10M. So
many in fact that I find it unusable for VHF transverter IF
duties here. The Corsairs and Pegasi that I run are much
cleaner. I know that Bob, K4TAX and some others were
successful at slaying most of the 10M RX spurs by making
extensive mods to the CPU board. I have not attempted to do
any of those mods and I'm not likely to do so either because
I'm focusing my efforts on other technology for my transveter
IF's. For the very near term I'll just keep using the Pegs
with Corsair's as sub RX's on VHF.
Duane
N9DG
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