Jim Nolan P-19 #426 Panache
>From: Bill Blohm <bblohm@hpbs1686.boi.hp.com>
>To: wwpotter@tscnet.com
>Subject: Re: Coax Connectors and cables
>Date: Fri, 10 Dec 1999 13:05:48 -0700
>
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> West Wight Potter Website at URL
> http://www.lesbois.com/wwpotter/
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>Good going. Something else that could help, at least when I first
>started messing with antennae this is what I was told, is to use
>a length of cable that's a multiple of the desired main operating
>frequency. That is, take the wavelength of the desired frequency
>and make the cable length some multiple of that. Let's say your
>frequency is 144.39 MHz. Your wavelength is 6.48'. Say your length
>from antenna connector to radio connector is 33 feet. Since 5
>wavelengths is only 32.4', you either re-route to use 32.4' or go
>with 6 wavelengths, or 38.88' of cable and lay the cable to neatly
>hide the rest of the cable. You can, of course, cut the cable to
>run 33', but there will be some slight mismatch.
>
>The way I learned it was .5L = 468/f
>
>where L is wavelength and f is the frequency in megahertz. Note
>that this provides you with half the wavelength, not the full
>wavelength.
>
>Bill B.
>P-19 #454, Dream Catcher
>Nampa, ID
>
>P.S. 144.39, for those of you that might be curious, is the
>national APRS frequency.
>
>Jim Nolan wrote:
> >
> > - - - - - - - - - - - - - - - - - - - - - - - - - - -
> > West Wight Potter Website at URL
> > http://www.lesbois.com/wwpotter/
> > - - - - - - - - - - - - - - - - - - - - - - - - - - -
> >
> > >From: Rye Gewalt <ryeg@vais.net>
> > >To: charles@falk.net, Potter List <wwpotter@tscnet.com>
> > >Subject: Re: Coax Connectors
> > >Date: Fri, 10 Dec 1999 05:33:57 -0500
> > >
> > >Charles Falk wrote:
> > >
> > > > Would a couple of BNC or TNC connectors on RG58 pigtails be better
>than
> > > > a PL259 on the cable from the mast connecting to an SO239 bulkhead
> > > > connector on the cabin roof?
> >
> > The UHF connectors can handle alot more power than either BNC or TNC.
> > UHF~2kW, BNC~10W TNC~25W. Also the UHF is less bothered by corrosion
>because
> > of its large area. A UHF connector that can feed through the cabin roof
>is
> > available from Pasternack Enterprises 949-261-1920, Irvine, CA. It is
>part
> > #PE9114 UHF female to UHF female bulkhead mount. It costs $8.95 in
>single
> > piece quantities. I would cover the outer portion with a rubber cap when
>it
> > is not in use.
> >
> > Do not splice coax cable. You can get away with splices in short runs
>(less
> > than 12" at 150 MHz) but on the boat the cable is 20-50 ft long. Any
>splice
> > or impedance bump will seriously limit the match between the antenna and
> > radio and could in some cases burn out the radios final amplifier. Use
> > connectors to join cables.
> >
> > Also a better cable than RG58 and still the same size is RG142. It has
>half
> > the loss but costs about 4 times as much. RG58 will have about 3 db loss
>per
> > 100' at 150 MHz and RG142 will have about 1 dB. In a typical boat
> > installation you will get about 60% more power to the antenna using
>RG142
> > over RG58. RG58 is .40/ft in 100' qty, RG142 is $1.63/ft in 100' qty.
> >
> > Over and out,
> >
> > Jim Nolan P-19 #426 Panache
>
> > Get Your Private, Free Email at http://www.hotmail.com
>
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