The INRAD 2.8 kHz filter was developed to help cure a dirty and sometimes
chirp-prone CW note on the Omni Six series transceiver To this end, the
filter achieves its goal. For a complete analysis and discussion of the
problem, the information may be available in the Ten-Tec reflector archives.
----- Original Message -----
To: Michael A. Newell <firstname.lastname@example.org>
Sent: Wednesday, February 10, 1999 6:00 AM
Subject: Re: [TenTec] Inrad 2.8K
>Its impossible to comment in depth when the INRAD web site does not
>give any specification for their TenTec filters. We need to know how
>many poles, the -60dB bandwidth, (for the shape factor) and preferably
>also the ultimate stopband. Its also essential to get some idea of the
>filter loss, especially for the narrow CW filters. Without this info,
>there is no real reason to even consider fitting an INRAD filter
>instead of the standard filters.
>The specification for Kenwood INRAD filters suggests that the filters
>are 8 pole, which is the same as TenTec. In that case, its all down
>to how well made the things are, because that will determine how well
>they work. I do have an INRAD-type 8 pole SSB filter here, for a Heath
>HW 101. It IS better than the standard Heath filter which is I
>believe a 6 pole filter. But the difference is not astonishing ...
>The INRAD 400 Hz CW filters do look like they might be very useful. I
>have asked INRAD for data; if I get it I will know more and I will
>pass it on !!
>Not sure I need a 2.8, either as the main stock filter in the Omni-V,
>or as an alternate in the 9 mHz front end. Now I do use a 1.8 in the
>second IF fairly often, (with the standard 2.4 up ahead of it) but I'm
>not sure I would want to use two cascaded 1.8 filters for SSB. The
>overall SSB passband would be restricted, to put it mildly.
>On CW I always use the 9 mHz 500 Hz filter and the 500 Hz second IF
>filter cascaded behind it. Occasionally I use the 250 instead of the
>second 500. They all work fine although the 250 demands careful
>All the time there is the front end 2.4 filter in line of course. It
>cuts out some of the crud before it hits the first 500. A wider 2.8
>filter there would not cut out as much, so maybe its strictly for the
>hi-fi buffs ??
>The bottom line is the spec of the INRAD filters. The more I think
>about it the more I wonder if changing filters will effect any real
>improvement over what I have now .... And I get the message that I'm
>not alone in wondering.
>On 10-Feb-99 Michael A. Newell wrote:
>> I would also be interested in posting your opinions to The
>> Anyone who has something substantive to say about the INRAD
>> filters is welcome to send it to me for posting.
>> Also, I would like a knowlegeable person to write something
>> up that's a little more formal that compares the INRAD
>> to the stock filters. Someone who can apply their technical
>> expertise to a discussion of these filters vs. the stock
>> Thanks and 73,
>> Mike -- WB4HUC
>> Austin, TX
>> http://wb4huc.home.texas.net/omni-vi/ - The Unofficial OMNI
>> VI Web Site
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