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[TenTec] Ten Tec vs. Inrad 9 MHz Filters

To: <tentec@contesting.com>
Subject: [TenTec] Ten Tec vs. Inrad 9 MHz Filters
From: n4py@earthlink.net (Carl Moreschi)
Date: Tue Apr 15 16:16:43 2003

There would be negligible difference by using the inrad filters in the
Orion.  99% of the time, the DSP filters won't even need the a narrow
roofing filter.  The difference between the tentec and inrad filters in this
application would be almost immeasurable.

Carl Moreschi N4PY
Franklinton, NC
----- Original Message -----
From: "Jim Reid" <jimr.reid@verizon.net>
To: <tentec@contesting.com>
Sent: Tuesday, April 15, 2003 6:53 PM
Subject: [TenTec] Ten Tec vs. Inrad 9 MHz Filters

> Hi,
> I would appreciate a lead as to where I could find performance
> curves for the Ten Tec filters say the 217, 218, and 219 optional
> available for use in the Orion.
> I believe the TT filters are "less" steep skirted close in,  but are
> actually more narrow further on out from the center frequency;
> thus actually would perform "better" in the roofing filter application
> in the Orion front end than the available Inrad models.  Curves
> for the Inrad filters are found at:
> http://www.qth.com/inrad/tentec_menu.htm
> Couple of examples from the above site:
> Inrad 400 Hz BW CW 9Mhz filter, the #759, is down 6 dB at
> a BW of 455 Hz;  and at 60 dB down it is 955 Hz wide;
> their 250 Hz filter, the #760, is down 6 dB at a BW of
> 315 Hz; and at 60 dB down it is 700 Hz wide.
> But,  I have been told these actually "come back" up
> and have less attenuation on beyond the close in curves
> shown by Inrad at their site.  I do not know if this is true!
> Why,  well "only" 60 dB down is really not that large
> an attenuation in some ham band situations,  and coming
> back up again could really be bad.
> But,  I don't know how to compare to the "standard" Ten Tec
> filters.  I had an Omni VI+ in the past equipped with the Inrad
> filters in all slots,  replacing the TT filters.  At the time I was
> not apprised of the possible benefit of staying with the standard
> Ten Tec units;  that is,  perhaps not as steep close in skirts,
> but they "stay  down",  hi.  Frankly,  I cannot say that the
> Inrad filters "really" made the Omni a better performer,  but
> I did not do a direct A/B comparison,  for obvious reasons:
> I only had one Omni,  hi.
> Any comments,  actual data per this topic would really be
> appreciated,  should you have any or know of a source.
> Would like my new Orion (coming in May?,  lot #2 somewhere)
> to have the best roofing filter performance possible,  giving
> the narrow IF-DSP filters the greatest opportunity to provide
> super selectivity.  BTW,  have ordered the TT 1.8 kHz and
> 500 Hz optional roofing filters to be included with my Orion.
> So far,  have heard of no one replacing Ten Tec filters in
> their Orion with the now available Inrad filters for that
> radio;  perhaps that is sacrilege!
> 73,  Jim  KH7M
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