Ken I think that you may have misunderstood where the roofing filter is in
the "food chain". The "stock" Omni V and VI have 2-pole filters at the very
front end of the 9 MHz IF board. These filters are 12 to 15 kHz (yes that's
kHz) wide and hard wired. Their purpose is a first line of defence for
nearby signals.
The InRad mod goes in front of this filter and gives the operator the option
to significantly narrow the front end of the 9 MHz board. It's location is
between the RF board and the 9 MHz board. The mod contains a 4-pole filter
(either 600 Hz or 2400 Hz). The NAR switch(s) are used to (a) control the
roofing filter and/or (b) the NAR filter. The roofing filter is not located
at the end of the 9 MHz "food chain" like the NAR filters. It is actually
at the opposite end of the 9 MHz schematic.
The roofing filter can be switched in or out so that the operator does not
lose any functions (e.g. FM or a wider 2,800 Hz IF filter) by installing the
mod.
I have installed the 2400 Hz version in my Omni V.9 and, other than a small
glitch with the cabling, found the process relatively painless.
73,
Rick
VE7TK
Website: http://www3.telus.net/ve7tk
---------------------------------------------
>Date: Thu, 13 Jan 2005 21:35:59 -1000
>From: Ken Brown <ken.d.brown@verizon.net>
>Subject: Re: [TenTec] INRAD Omni VI roofing filter kit - success
>To: tentec@contesting.com
>Message-ID: <41E7765F.7050306@verizon.net>
>Content-Type: text/plain; charset=us-ascii; format=flowed
>
>Hi Jason,
>
>I understand why someone with a non plus or version 3 upgraded Omni VI
>would want the Inrad modification, in order to get another
>narrow 1st IF
>filter option. And I can also understand that even if you already had
>two narrow filter options in a version 3 or Omni VI +, there
>might still
>be some improvement in BDR by adding the Inrad modification. What I
>don't understand is why don't you have a filter in your Omni VI NAR
>slot? It seems like it would have been much easier just to
>plug a filter
>in there. That would have also been a big improvement, even if
>not quite
>as good as the Inrad mod, and cheaper and easier to do.
>
>DE N6KB
>
>>
>> I don't have a filter in my Omni VI NAR slot - it used to be
>my "Mute"
>> button but now it becomes the enable/disable switch for the INRAD
>> roofing filter.
>
>
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