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Re: Best place to get LM600?



Allen,

Unless you are terribly limited by uplink power or quite long feedlines, I
don't think you need LMR 600. I examined that alternative myself, and went
with LMR-400. It is excellent coax. I have an 80' run from my FT-847 to the
CP-30 M2 ...and much of the time I have no need for more power...LEILA dope
slaps me enough as it is. When squint angles are poor, more power helps.

Put it this way. If you have a brick amp that can do 100w (which was very
common during AO-10 and AO-13 days, then unless you have 150' or more of
coax run, use LMR-400 which uses standard connectors. There is nothing to be
gained with 600 unless you have very long feedlines at 70cm. You will need
special connectors, and it won't do well around a rotor. LMR-400 works just
fine around rotors. (I use two...a Yaesu G-500 for az and the standard Yaesu
elevation rotor.

On the mode S downconverter side, LMR-400 is wonderful for the 145 mhz
downconverter frequency. I replaced 135' of RG8/x with 80' of LMR-400 for
the 2m downconverted freq and eliminated the need for the internal preamp on
the FT-847 to get good S-meter readings. Reducing loss on the 2m
downconverted freq does little to improve your ability to hear, i.e., it
doesn't change your system sensitivity...it just makes your S-meter more
active. Most downconverters already have too much gain, so the coax loss
from DC to the radio is actually a beneficial attenuator, as long as it
doesn't get too high.

If you have a Windows machine, I have two recommendations for you.

1. Go to the timeswire website and download their coax loss calculator

2. Get a copy of the ao40 spreadsheet that is so popular here on the list,
enter in the values of your system, and examine carefully how much uplink
power you are going to need. The spreadheet is a JEWEL of a program! It even
shows you when you are going to get slapped up side the head with LEILA.

Both programs are free.  AO-40 Ground Station Evaluation Tool by Gene
Marcus, W3PM requires Microsoft Excel spreadsheet. I renamed the file, so I
can't tell you it's original name, but it's something like ao40*.xls, the *
being a character  can't recall.

You can learn an awful lot about your receive setup, as well as uplink
requirements by playing with this amazing tool for a just a few minutes. 73

...hasan, N0AN

----- Original Message -----
From: "Allen Fugelseth" <allen@cruzio.com>
To: "'amsat-bb@amsat.org'" <amsat-bb@AMSAT.Org>
Sent: Wednesday, November 14, 2001 6:56 PM
Subject: [amsat-bb] Best place to get LM600?


> I don't know what type of coax most  of the serious satellite users are
> using.  I have been looking at what's available and I don't like the loss
> figures for 450 MHz.  I am seriously thinking about  Times LM 600.  Where
is
> a reasonable place to get it?
>
> Is LM 600 good for rotor service?
>
> It looks like LM 600 takes special coax connectors?
>
> Besides hard-line what is recommended for  450 MHz and 144 MHz?
>
>                                                     73, Allen WB6RWU
>
> ----
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