RF Coaxial Cable

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barefootindian
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RF Coaxial Cable

Post by barefootindian »

Hi again folks, I would like to know if there are any real differences between RG Mini 8, Ant 240 ( equivalent to) LMR 240, Ant 195 Coax For a run between Antenna and Radio of around 75 to 90 meters.
When losses are mentioned re coax cable is it actual audio loss or is it electrical loss due to lengths perhaps being too long??
I have a hill 50 or so meters from my qth and I would like to take advantage of it to boost my tx signal whilst running barefoot hence the long length of coax question
Should I be thinking RG213 or RG400?? Although I already have RG Mini 8 and wonder if it should do the job adequately for me?
What say ye?
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ch25
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Re: RF Coaxial Cable

Post by ch25 »

90m of coax I would run 7/8 hardline.
Example:
RG213 is 2,425 dB loss. 4W in, 1,667 at the antenna.
CNT240 is 3,973 loss, 4W in, 2,398 at the antenna.
Assuming, that antenna is R=50 Ohm and X=0. Bigger antenna mismatch, bigger loss.
Source: https://ac6la.com/tldetails1.html
Chris
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barefootindian
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Re: RF Coaxial Cable

Post by barefootindian »

Hi Chris thanks for the reply. I did some rough calculations myself but as I am intending to tx on ssb I was calculating on a 12 watt output on 27.555 for example.
So using RG213 on a length of 90 meters I reckoned my db loss on power out would be approximately 5.814db whereas if I was to use 7/8 hard-line then I would have less losses out powerwise. 12 watts is my max out of the radio. Using LDF4-50A the loss would be 1.025.Using LDF5-50A the loss is roughly .560 and UsingLDF6-50A the loss is roughly .389 db. So where does that leave me? I've got a choice to make and decide if I'm gonna spend a couple of hundred euro on 7/8 line in order to save on losing roughly 1.25db's or slightly more than half a db or slightly less than a third of a db, that's if my very rough calculations can be heeded.
The RG 8 mini gives me a loss of 4.667db's and RG213 gives me a loss of 3.147db's at 90 meters. I don't think that that, is bad at all at all.
The 7/8 is expensive so I've some thinking to do, anyway Chris Thanks again for your reply.
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ch25
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Re: RF Coaxial Cable

Post by ch25 »

I think you should aim to less loss you can afford. 12W is not much and lose half of that in the cable is not what you want.
My hint:
For single band antenna you can use CATV coax. It is cheap, low loss and widely available. I use it for a few of my antennas. 10mm diameter, gel inside for direct bury.
2 conditions: one band antenna, cable must be cut to 1/2 wavelength multiplication minus velocity factor. In your case 10 wavelength.
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Mitch
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Re: RF Coaxial Cable

Post by Mitch »

Can you set your radio up on the hill and just run a power cable to the house? I'd be cheaper.
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barefootindian
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Re: RF Coaxial Cable

Post by barefootindian »

I don't wish to broadcast out in the open. I'm lookin for real solutions so broadcasting from under the antenna with electric cable going to house won't be happening .
barefootindian
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Re: RF Coaxial Cable

Post by barefootindian »

Thanks for the answer Mitch
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Re: RF Coaxial Cable

Post by grafter »

If I couldn't find enough lengths of LDF450 from decommissioned radio sites Westflex 103 would be my choice, good loss figures and not too pricey. Westlake sell a 100M drum for £150.
my friend grafter, seems like you are using a very offensive tone in the reply.
barefootindian
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Re: RF Coaxial Cable

Post by barefootindian »

I'll have a look at some rg-6 and see where I go from there, but first I'll re- measure where I intend to erect my antenna to make sure my maths is correct on this before I take it any further. Thanks for your helpful input Chris.
barefootindian
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Re: RF Coaxial Cable

Post by barefootindian »

grafter I never thought of Westflex 103, but I'll consider that. Thanks for your input too.
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Re: RF Coaxial Cable

Post by G8GGP »

Just a suggestion...whatever you do you are going to get a good amount of loss. I don’t know what access is to your site but could you put a couple of big batteries up there with a solid state linear/preamp?, a couple of leisure batteries would last ages between charges.
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Unit 148 Mobile
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Re: RF Coaxial Cable

Post by Unit 148 Mobile »

BF,

My 2p.

A branded RG213 such as that from Belden has under 1db of loss at 30Mhz per 30m in length.

Belden only show attenuation at 10MHz & 50Mhz on their site but RF Parts show the 30MHz spec: https://www.rfparts.com/rg213-u.html

So if you're that worried about attenuation you have less than 3db at 90m.

Personally I would not be too concerned, however for a 'noticeable' improvement you will have to spend real money with Commscope's Andrew cable or equiv as Chris suggested above.

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barefootindian
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Re: RF Coaxial Cable

Post by barefootindian »

Thanks both to Unit 148 Mobile and G8GGP and to all who gave good and valuable suggestions to my initial question. So I emailed a few different coaxial cable suppliers and the cost of my " Project" could turn out quite expensive.
I've decided to spend some money on a shed and run electric cable from the house and enjoy the hobby from up on the hill, as suggested earlier by Mitch. It will happen a little later on this year hopefully once the budget allows for it.Thanks to all for your valuable and thoughtful suggestions and help in answer to my query.
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