[Public-List] VHF cable

Wehicks wehicks at gmail.com
Wed Apr 17 20:30:04 PDT 2019


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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