[Public-List] VHF cable

[Paul Wilson]

LMR 400 is much larger -- .405" diameter, and fairly rigid. (Product cut
sheets will show you the bending moment for various cabling, which gives
you an idea of how flexible it is.) It's probably not something I would
want to try to fish down the mast. I've used it in my home "ham shack" for
a VHF/UHF antenna. My home installation HF antennas are fed with RG-213. In
my view neither cable would be easy to handle in a boat installation. One
reason RG8x is so popular is that it's inexpensive and mechanical
characteristics are capability with marine and mobile installations.

Paul / KI4PW / Slainte #129

On Wed, Apr 17, 2019 at 11:47 PM Wehicks via Public-List <
public-list at lists.alberg30.org> wrote:

> What about Lmr 400 ? For just a few bucks more??
>
> Sent from my iPhone
>
> > On Apr 17, 2019, at 9:42 PM, Paul Wilson via Public-List <
> public-list at lists.alberg30.org> wrote:
> >
> > Sorry, I goofed on the Practical Sailor recommendation. I wrote without
> > checking the article first, and went from memory. They recommend the
> > *N-Type connectors. Type "F" are commonly used for cable TV.
> >
> > Bottom line is buy the best cable you can afford that meets the physical
> > characteristics you're looking for--diameter, bend radius, etc.
> >
> >> On Wed, Apr 17, 2019 at 9:20 AM Paul Wilson <dcmcrider at gmail.com>
> wrote:
> >>
> >> I should mention than dB are logarithmic, so a difference of -3 dB is
> >> double the power loss. If your radio is rated at 25W at the transmitter
> >> output, 3 dB of loss means you're radiating 12.5W at the antenna.
> >>
> >> Assuming your coax cable run is 50' (35' the up mast and 15' to your
> >> radio) the difference between LMR200 and RG8X is 0.4 dB. In terms of
> power
> >> ratio at 50' of run LMR200 = 0.64; RG8X = 0.58. Assuming 25W at the
> radio
> >> LMR200 means you're radiating 16W with LMR200; with RG8X it's 14.5 W.
> >>
> >> Quality and properly installed connectors that are well-sealed against
> >> water infiltration are also critical to long-term performance of the
> >> antenna and feed line. Water in the dielectric material (between the
> shield
> >> and core) is the downfall of coax cable. The February 2019 issue of
> >> Practical Sailor discusses this issue in some depth. They recommend "F"
> >> style connectors in lieu of the ubiquitous PL259/SO239 combo.
> >>
> >>> On Wed, Apr 17, 2019 at 8:31 AM Paul Wilson <dcmcrider at gmail.com>
> wrote:
> >>>
> >>> Here's a link to some coax attenuation charts, as well as cable
> diameters.
> >>>
> >>> http://www.w4rp.com/ref/coax.html
> >>>
> >>> LMR200 has 3.9 dB of loss per 100' at 150 MHz. (Marine VHF band is ~160
> >>> MHz.) RG8x has 4.7 dB/100'.
> >>>
> >>> On Wed, Apr 17, 2019 at 7:27 AM Rod Symmes via Public-List <
> >>> public-list at lists.alberg30.org> wrote:
> >>>
> >>>> RG8  and  RG8X are not the same item.
> >>>> RG8 is nearly 1/2" diameter, stiff and heavy.   8x is half the size
> and
> >>>> weight with ALMOST as low loss.
> >>>> I don't know the spec for LMR 200 to say how much of an improvement
> over
> >>>> RG8X it would be.
> >>>>
> >>>>
> >>>> Cheers,  Rod
> >>>>
> >>>> -------- Original message --------
> >>>> From: Philip Bartlett via Public-List
> >>>> Date:16-04-2019 10:53 PM (GMT-05:00)
> >>>> To: Alberg 30 Public List -- open to all
> >>>> Cc: Philip Bartlett
> >>>> Subject: Re: [Public-List] VHF cable
> >>>>
> >>>> You might want to use LMR 200. It’s lower loss, thinner and half the
> >>>> weight of RG8.
> >>>>
> >>>> Philip
> >>>>
> >>>> Sent from my iPhone
> >>>>
> >>>>> On Apr 16, 2019, at 5:41 PM, Christian Douglas via Public-List <
> >>>> public-list at lists.alberg30.org> wrote:
> >>>>>
> >>>>> I cut the existing VHF cable when I lowered the mast. Need to place a
> >>>> new
> >>>>> run to the top of the mast. The old cable is RG8X. Any thoughts on
> the
> >>>> new
> >>>>> cable? Any reason why I’d need a different cable?
> >>>>>
> >>>>> Christian
> >>>>> Kittiwake #76
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