Re: [amsat-bb] How far should one separate a LNA and its associated downconverter, and Why?

["Lee" <lee-fl@xxxxxxxxxx>]

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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