excellent comments.
73
Colin, V A6BKX
----- Original Message ----- 
From: "Kenneth Lee" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, November 26, 2007 8:08 AM
Subject: Re: length of coax


> The amount of loss will depend on the cable you use
> and the bands you are
> interested in.  On the Cable Experts web page I see
> the LMR 400 cable has a
> loss of .7db per 100 feet at 30 Mhz, 1.5db loss at 150
> Mhz and 2.7db loss at
> 450 Mhz.  If your interest is only hf then you should
> be ok with the thicker
> rg-213/9913 but for VHF/UHF you might want to consider
> hardline, or you
> might be able to live with a loss of 3db vhf and 6db
> uhf? .  Also, you could
> consider ladder line for HF, it has much less loss
> than coax, you can
> convert the ladder line to coax with a balun just
> before you bring the line
> into the shack.
> Check out this web page:
> http://www.amsat.org/amsat/articles/houston-net/coax.html
>
> Using 2 meters for downlink, RG-8 would have a line
> loss of 2 dB and on 70
> cm a loss of 3.8 dB. RG-58 has a loss of 7 dB and 15
> dB respectively. As you
> can see between these two common types of coax you can
> have significantly
> greater gain by choosing RG-8 over RG-58.
>
> But the 2 or 3.8dB loss is not acceptable in satellite
> work. We would like
> this loss to be as close to zero as possible since the
> signals from the
> satellites
> are so weak.
>
> Now, let's look at Belden 9913/9913F. On 2m, it has a
> loss of 1.6 and on
> 70cm it is 2.8 dB. LMR-400 has a loss at 70cm of 2.7
> dB and at 1 GHz 4.0 dB.
> Half
> inch hardline has a loss on 2m is only .9 dB and on
> 70cm it is 1.9 dB. This
> -- when compared to RG-8 or RG-58 -- would be a
> fantastic gain. Belden 9913
> is a solid core coax. I use a coax that is similar to
> Belden 9913 but is a
> stranded core that makes it easier to manipulate and
> will not crack as
> easily
> when it gets cold.
>
> Belden 9913F is their new product that was not
> available when I set up my
> station. It is identical in properties to 9913 except
> that it is a stranded
> core
> with foamed gas injected interior.
>
> If you are going to work 1.2 gig, Belden 9913/9913F
> loss would be 5.8 dB,
> once again, the LMR-400 loss is only 4.0 dB and half
> inch hardline loss is 3
> dB.
> ...
>
>
>
> ...-.-
> 73, Ken -N5SWR
>
> There are 10 types of people in the world, those who
> understand binary and
> those who don't.
>
>
> -----Original Message-----
> From: For blind ham radio operators
> [mailto:[log in to unmask]]
> On Behalf Of Gery Gaubert
> Sent: Monday, November 26, 2007 9:33 AM
> To: [log in to unmask]
> Subject: length of coax
>
> I finally got a tower.  40 ft.  I now have a problem
> though.  I can only put
> the tower in one place.  I will need to run abount 200
> of coax to get from
> the top of the tower to the radio.  I realize that the
> shorter the run the
> better the reception and probably the transmition.
> How much of a loss will
> I experience?  I guess what I am trying to ask is can
> I live with the loss?
>
>
>
>
>
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