W0YG wrote:
>Close in, as in 2kHz spacing per Sherwood
Engineerings website listed below, are impartial test results which show how
well the various receivers compare. This is where the Orion shines with the
600 Hz INRAD filter. The 7800 falls off a bit at that spacing because the
interfering signal is inside Icom's narrow roofing filter.
http://www.sherweng.com/table.html
Orion with the 600 Hz Inrad 762 is actually
even better than shown above. The above table
shows data using only the stock 1000 Hz filter.
According to Sherwood, the Orion/762 combo is:
"At 5, 10 and 20 kHz, there is no significant (IMD) difference between the
stock 1.0 kHz Ten-Tec filter and the Inrad filter.
At 2 kHz spacing, the improvement is on the order of 6 to 7 dB.
At 1 kHz spacing the improvement is closer to 10 dB."
http://users.vnet.net/btippett/inrad_.htm
This would put the Orion/762 IMD performance
at 2 kHz spacings in the ballpark of 99 to 100 dB
(93 per the table above plus an additional 6-7 dB).
Nearly every other recent transceiver is phase noise
limited to about 80 dB at these spacings, and this
includes the IC-7800, Elecraft K2 and "probably" the
FT-9000 based on what I've seen for 5 kHz spacings
in the August QST Review (the ETR should be available
in a few days which will show performance at 1-2 kHz
spacings). Phase noise becomes an over-riding factor
at very close spacings, and only Ten-Tec seems to
have addressed it with Lee Jones' phase-noise
optimized synthesizer design in Orion.
http://radio.tentec.com/cms-files/565_syn_article.pdf
73, Bill W4ZV
P.S. Icom's advertising agency does not seem concerned
about the FTC's Truth in Advertising law. If someone
were to take them to court, it would be a very easy
case to prove deceptive and misleading advertising.
I have little respect for any company who so flagrantly
abuses Truth in Advertising.
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