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Conductive Foam, was Re: How far should one separate a LNA and its associated down converter, and Why?



Thanks Domenico.

I'm sitting here thinking of all the sheets of this stuff I have tossed
out after buying parts and such. Now I don't have any. Where can I buy
this stuff?

Bill
w1pa


----- Original Message -----
From: "i8cvs" <domenico.i8cvs@tin.it>
To: "Bill Acito W1PA" <w1pa@hotmail.com>; "AMSAT-BB"
<amsat-bb@amsat.org>
Sent: Monday, April 07, 2003 10:23 AM
Subject: R: [amsat-bb] Re: How far should one separate a LNA and its
associated down converter, and Why?


>
> ----- Original Message -----
> From: Bill Acito W1PA <w1pa@hotmail.com>
> To: <amsat-bb@AMSAT.Org>
> Sent: Monday, April 07, 2003 4:47 AM
> Subject: [amsat-bb] Re: How far should one separate a LNA and its
associated
> down converter, and Why?
>
>
> > > I also experienced 13ULNA preamp instability and solved it by
putting
> > a 1"
> > > square piece of black anti-static foam in the DEM enclosure.  It
was
> > about
> > a
> > > 1/4" thick.  My 13ULNA is connected to my downconverter through a
> > double
> > > male N barrel connector.
> > >
> >
> >
> > While I am digging up the QEX reference, can the same thing be
> > accomplished by putting additional shielding (a copper or brass
plate)
> > immediately over the ULNA board, in close proximity? I worry about
the
> > foam breaking down and shedding.
> >
> > Bill
> > w1pa
> >
>
> Bill,
>
> Additional shielding inside the box immediatley over the LNA board do
> not prevent the RF energy to transfere from one stage to the previous
> one inside the box.
>
> On the other hand the conductive black foam absorbes and dissipates
> the circulating RF  fields inside the box and it make very easy to cut
> regenerative feedback  between the input and output of low signal  and
> high gain amplifiers.
>
> Dont worry about the possibility of foam breaking down is you use a
> good quality elastic glue like BOSTICK for example.
>
> 73" de i8CVS Domenico

----
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