[TenTec] IMD Measurements - Omni VI Roofing Filters

[Tommy]

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 at alum.mit.edu>
To: <tentec at 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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