[Public-List] VHF cable

[Paul Wilson]

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
>>> > _______________________________________________
>>> > These businesses support your Association:
>>> > http://www.alberg30.org/store/A30supporters.html
>>> > Please support them.
>>> > _______________________________________________
>>> > Public-List mailing list
>>> > Public-List at lists.alberg30.org
>>> > http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>>
>>> _______________________________________________
>>> These businesses support your Association:
>>> http://www.alberg30.org/store/A30supporters.html
>>> Please support them.
>>> _______________________________________________
>>> Public-List mailing list
>>> Public-List at lists.alberg30.org
>>> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>> _______________________________________________
>>> These businesses support your Association:
>>> http://www.alberg30.org/store/A30supporters.html
>>> Please support them.
>>> _______________________________________________
>>> Public-List mailing list
>>> Public-List at lists.alberg30.org
>>> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>>
>>