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Re: Re: indoor vs. outdoor downconverter



>From: Ronald Long <rlong3@columbus.rr.com>
> > Eduardo, you won't hear anything with an indoor downconverter.
> > It needs to be _AT_ the antenna!
>
>Since there are always newcomers ...
>
>Well not necessarily. As Ed Cole pointed out an option being used by many 
>folks is a good preamp (of adequate gain) at the antenna, followed by 
>ordinary RG6 cable, with the downconverter in the shack. This has some 
>advantages like having the downconverter at a stable temperature. The 
>ground station evaluation tool (spreadsheet) shows that it works.
>It is available at:
>http://home.hiwaay.net/%7Emmarcus/download/ao40v2.0.xls
>
>Ron, w8gus.

Ron,

What you say is correct, but to avoid misleading Eduardo, there must be a
low noise stage (preamp or the downconverter) placed right at the antenna
connector to avoid serious loss of sensitivity.  This is because the
overall noise figure is set by that first stage, and any cable loss before
that stage is directly added to the noise figure.

So if you place a preamp directly at the antenna then you can have the
downconverter inside using a reasonable feedline.  But the UEK is about the
only downconverter that has sufficiently low noise figure and gain not to
require a preamp, IF, and ONLY IF it is placed at the antenna!  I am not
using the UEK so cannot speak to its freq. stability, but I suspect that it
will not be adversely affeccted by outside temp extremes...other
downconverters reportedly are.  MY Drakes are  quite stable in the Alaska
environment of -30 to +20C after the intial half-hour warm up on power-up!

Wx protecting your device is not as difficult at it might look.  I'm using
a smal plastic equipment enclosure form radio shack.  Ohters have used
plastic sandwich boxes, etc.

Ed

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