[TenTec] Inrad #352 Filter for Orion

[Richard Detweiler]

Just as a side note,  Inrad is selling the #352,  even it was not listed on 
thier web site.

Ask for it and then add the Ten Tec filter board.

Was able to buy one last month for the same price.

If there is a place to put picturs, can show the finished filter with the 
surface mounted caps.

73's
Rich
K5SF

>From: Bill Tippett <btippett at alum.mit.edu>
>Reply-To: tentec at contesting.com
>To: tentec at contesting.com
>Subject: [TenTec] Inrad #352 Filter for Orion
>Date: Sun, 06 Jun 2004 21:39:10 -0400
>
>         Rob Sherwood NC0B of Sherwood Engineering recently
>made some IMD measurements of the Inrad #352 650 Hz roofing
>filter (inserted in Orion's 1000 Hz position) that several of us made
>as a special order in January.  Here is a summary of Rob's results:
>
>> > At 5, 10 and 20 kHz, there is no significant difference between the
>> > stock 1.0 kHz Ten-Tec filter and the Inrad filter.
>> > At 2 kHz spacing, the improvement is on the order of 6 to 7 dB.
>> > At 1 kHz spacing the improvement is closer to 10 dB.
>> > There is some strange hysteresis of a couple dB, as you change the 
>>level
>> > around.  The IMD does not act exactly as one would expect.
>> > I am guessing the digital AGC is doing strange things, causing the
>> > hysteresis.
>> >
>> > The insertion loss of filters #2 and #3 are identical to the Ten-Tec 
>>1.0
>> > kHz filter.
>
>         The bottom line summary is that the #352 allows Orion to retain
>its 20 kHz spacing IMD performance of ~96 dB all the way down to
>1 kHz for the modest cost of about $40 if you are willing to warm up
>your soldering iron.  Rob's summary below includes only 1000 Hz filter
>data but you can calculate performance numbers for the #352 using the
>above data:
>
>http://www.sherweng.com/Dayton_2004/Dynamic_Range_Data.pdf
>
>More info on building these filters is at the site below:
>
>http://users.vnet.net/btippett/inrad_.htm
>
>Barry N1EU also has a site on building the filter using NPO disc
>capacitors instead of the supplied surface mount caps, but qsl.net is
>down at the moment and I cannot bring up the URL.
>
>                                 73,  Bill  W4ZV
>
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