[TowerTalk] Resistance of RG-8 cable?

[K1TTT]

There is one big advantage of the return loss test, besides measuring double
the loss (down and back) which gives a more sensitive test... and that is
you don't have to go to the far end of the cable.  I can test most of my
main cables here from the shack by just opening the remote switch and
putting a bit of power down the line... makes for a quick and easy test with
built in instrumentation, just flip a switch and its basically done.


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
 

> -----Original Message-----
> From: gdaught6 at stanford.edu [mailto:gdaught6 at stanford.edu]
> Sent: Thursday, December 10, 2009 21:03
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Resistance of RG-8 cable?
> 
> K1TTT wrote...
> 
> > I think a better test is a return loss test at 10m, leave the
> > far end either open or shorted and measure the reflected power or swr,
> the
> > higher it is the better the cable.
> 
> Or, put a good dummy load at the far end, and measure the RF power out of
> the
> exciter into the cable.  Now, without changing RF level, move the power
> meter down
> to the dummy load end and measure the power being delivered to the dummy
> load.
> Now you've measured the actual loss in the cable.  Compare it with the
> manufacturer's specified value, and you know if it has degraded.  If the
> resulting loss
> is something you want to live with, keep using the cable!
> 
> Remember, the loss of brand-new, high-quality cable IS NOT zero!
> 
> 73,
> 
> 
> 
> George T Daughters, K6GT
> CU in the California QSO Party (CQP)
> October 2-3, 2010
> 
> 
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