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



I HAVE MY 1ST CK722 ALSO---I USED IT AS AN AUDIO AMPLIFIER
ON MY CRYSTAL RADIO SET ABOUT 51 YEARS AGO

----- Original Message -----
From: "Dr. Jim Akers" <jakers@ECE.MsState.EDU>
To: "Bill Acito W1PA" <w1pa@hotmail.com>
Cc: "i8cvs" <domenico.i8cvs@tin.it>; "AMSAT-BB" <amsat-bb@AMSAT.Org>
Sent: Monday, April 07, 2003 10:13 AM
Subject: Re: [amsat-bb] Conductive Foam, was Re: How far should one separate
a LNA and its associated down converter, and Why?


What?! A ham throws something out???  Really hard to believe ,Bill:)  I
still have the first CK722 Transistor that I bought and that was when they
first came out at about $15.00 a pop!! That should tell you something
about my age:) My XYL gave up on me years ago and just lets me keep the
stuff.

73...Jim...W5VZF.




Dr. Jim Akers
Dept. of Electrical
and Computer Engineering
Miss. State Univ.


On Mon, 7 Apr 2003, Bill Acito W1PA wrote:

> 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
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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>
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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