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Re: How far should one separate a LNA and its associated downconverter, and Why?



Other than the possible mismatch mentioned by others there would be no
reason and considering all the variables it is not surprising that they were
mumbling.

I run with my DEM 13ULNA connected directly to my Drake d/c through a double
male N-barrel connector and have seen no problems.

Lee-KU4OS

----- Original Message -----
From: "Eric Rawson" <ericrawson@rawsonoptics.com>
To: <amsat-bb@AMSAT.Org>
Cc: <kn6kc@arrl.net>
Sent: Friday, March 28, 2003 2:32 AM
Subject: [amsat-bb] How far should one separate a LNA and its associated
downconverter, and Why?


> I own a 2.4 GHz LNA (DEM 13ULNA) mounted at the focus of a 2' x 3' BBQ
dish.
> The dish is modified for circular polarization (aluminum screen covering,
> 5-turn helical feed).  The LNA connects via a short run (~2') of coax to
my
> downconverter (DEM 2400-144).  When I bought these last year, I was told
> that the coax run between the LNA and the downconverter should be "more
than
> a few feet".  When I asked why, I was given a mumble about
> "interaction"...it was rather vague.
>
> Hence, my question.  Is it really necessary to separate an LNA from its
> associated downconverter with some length of coax? If so, why?  What,
> exactly, might happen if you, for example, mounted them within inches of
> each other?  And how far apart must they be separated (i.e., how many feet
> of coax) to avoid this problem, whatever it is?
>
> Eric Rawson, KN6KC
>
> ----
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