Yes, 600hz for CW is correct. At least that is what I have ordered
for my Plus. George also mentioned in a telephone conversation that
he had tried building a roofing for the Icom IC-781 but could never
get that to work correct due to the 781's circuit design. His 600hz
filter and moving the standard filters as you previously suggested,
just works terrific in the Orion.
Tom - W4BQF
"So you have enemies?
Good.
That means you have stood up for something,
sometime in your life."
--Sir Winston Churchill--
----- Original Message -----
From: "Bill Tippett" <btippett@alum.mit.edu>
To: <tentec@contesting.com>
Sent: Friday, December 24, 2004 7:16 AM
Subject: [TenTec] IMD Measurements - Omni VI Roofing Filters
VE7TK wrote:
>My discussions with George (W2VJN) at InRad suggest that an Omni
>VI+ with
the new (soon to be out) InRad roofing filter may be a worthy
competitor
when it comes to IMD dynamic range (even stock it's not too
shabby). George
indicated that "the improvement for close in signals is quite
dramatic and
places the Omni VI into the group of today's top performing
radios."
Very true and I know of at least one person who has been
using a
homebrew version of this in an Omni VI for about a year. The
modified
Omni has a similar front-end design to Orion and performance
should be
very similar to the Orion with the #762 filter.
>The filter will be available in a 600 Hz and 2400 Hz version.
>The first
batch, to those of us who got on the pre-production order, should
be shipped
late next week. Hopefully a modified rig will soon make it to
Sherwood for
some independent tests.
Are you sure about that 600 Hz version? George's white
paper below
says it is a 400 Hz version, which is one reason I feel it could
do slightly
better than Orion with Inrad's 600 Hz #762.
http://www.qth.com/inrad/roofing-filters.pdf (page 6)
"Ten Tec Omni VI series: We are presently working on a roofing
filter mod for
the Omni VI+ radios. Plans are not quite formalized yet, but some
preliminary
data from our lab is shown below.
Signal Spacing IMD DR Filter Bandwidth
20 kHz 100 dB 2800 Hz
5 kHz 93 dB 2800 Hz
20 kHz 100 dB 400 Hz
5 kHz 100 dB 400 Hz
1 kHz 90 dB 400 Hz
We hope to make this unit available in the late fall or winter of
this year."
In any event, I suspect two Ten-Tec rigs will be at the
top of
Sherwood's list for a long time to come, and it will just be
interesting
to see which is #1 and which is #2...they both should be very
close.
73, Bill W4ZV
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