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Re: [TenTec] Inrad 762

To: <tentec@contesting.com>
Subject: Re: [TenTec] Inrad 762
From: "Tommy" <aldermant@alltel.net>
Reply-to: tentec@contesting.com
Date: Sat, 14 Aug 2004 13:15:56 -0400
List-post: <mailto:tentec@contesting.com>
Tody,

I concur with Bill's writting's. I didn't have the 1.8kc filter in my Orion,
so I moved the 1kc filter into the 1.8kc slot, put the 600hz filter into the
1kc slot, and left the 500hz and 250hz filters installed and enabled. Really
sounds quite impressive, especially in this CW contest going on this
weekend.

The Inrad filter is almost a half an inch taller than the TT filters, but I
did put the cover back over the filters, but just did not tighten it down
fully. If I was going to keep my Orion, I would modify the filter cover.

Tom - W4BQF

----- Original Message -----
From: "Bill Tippett" <btippett@alum.mit.edu>
To: <tentec@contesting.com>
Sent: Saturday, August 14, 2004 11:10 AM
Subject: [TenTec] Inrad 762


> Hi Toby,
>
> W4CAK wrote:
>  >Has anyone tried putting the New Inrad #762 in the 500hz slot of the
> Orion.  Since the 1khz filter does an excellent job down  to 380 hz, would
> this not be a better use of the 762?
>
>          That won't work very well for several reasons:
>
> 1.  The 500 slot always has the second amplifier engaged...thus it
> should still be introducing IMD products.
>
> 2.  The 4-pole Inrad 762 has less insertion loss than standard 8-pole
> 500 Hz filters, aggravating the fact that the 500 position already has
> too much gain, even for the standard 500 Hz filters.  TT used a
> fixed 12 dB gain amplifier for both the 500/250 slots.  That is a
> good match for the 250's high insertion loss but too much for a 500.
>
> 3.  The center frequency of the 762 is 9.001500 but Orion thinks
> the 500 position has a 9.000750 Hz center frequency.  Thus the
> filter will not be correctly centered, although you can partially
> compensate for this by using both C.F. Adjust and PBT.  I think
> it can be made to work for UCW but not LCW (could be the other way
> around in the case you propose).  If you compensate using PBT,
> signals will disappear any time you switch to a different roofing
> filter.
>
>          I went through the same thinking when first looking into this
> filter issue, but I tried installing the 500 Hz filter into the
> 1000 Hz position.  That doesn't work well either for similar reasons.
>
>          Just plug your 762 into the 1000 Hz slot and everything works
fine.
> If your 1800 slot is empty, put your 1000 there.  If you already have
> an 1800, simply set your 1000 aside...you'll never miss it for reasons
> I've explained many times (1800 & 1000 being equivalent IMD fighters
> down to 2 kHz spacings where the 762 will take over and is far
> superior to either).
>
>                                                  73,  Bill  W4ZV
>
>
>
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