[TenTec] Inrad 762

[Toby Pennington]

Tommy, I thought the whole idea of the 600hz filter was to get better IMD
from 750hz  on down to 100 hz, so I wonder about you keeping the two other
filters enabled.  Have you tried just the 600hz with the 500 and 250 hz
filters disengaged. If so, what have you noticed.  First I have heard about
the filter cover not being able to be tightened all the way down. Hope this
is not much of an issue.      Toby W4CAK

----- Original Message ----- 
From: "Tommy" <aldermant at alltel.net>
To: <tentec at contesting.com>
Sent: Saturday, August 14, 2004 1:15 PM
Subject: Re: [TenTec] Inrad 762


> 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 at alum.mit.edu>
> To: <tentec at 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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