[TenTec] Inrad 2.8K

[patents@dx0man.prestel.co.uk]

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
tuning.

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.

John G3JAG
 
On 10-Feb-99 Michael A. Newell wrote:
> 
> I would also be interested in posting your opinions to The
> Site.
> 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
> filters
> to the stock filters. Someone who can apply their technical
> expertise to a discussion of these filters vs. the stock
> ones.
> 
> Thanks and 73,
> 
> Mike -- WB4HUC
> Austin, TX
> http://wb4huc.home.texas.net/omni-vi/ - The Unofficial OMNI
> VI Web Site
> 
> 
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----------------------------------
E-Mail: patents@dx0man.prestel.co.uk
Date: 10-Feb-99
Time: 09:39:16
John Crux
Consultant in product forgery - Asia and
Africa

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