RF Coaxial Cable

The place to talk about specific radios, equipment and accessories. Do you prefer the latest generation of rigs and antennas or do you like the classics? Discuss it here!
Post Reply
barefootindian
Regular
Regular
Posts: 86
Joined: 30 Dec 2011, 17:56
Call Sign: 29SC01
Location: an dubh linn

RF Coaxial Cable

Post by barefootindian » 14 Jan 2020, 22:06

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?

User avatar
ch25
Radio Addict
Radio Addict
Posts: 730
Joined: 03 Dec 2016, 11:07
Call Sign: Lemmy
Location: Poland

Re: RF Coaxial Cable

Post by ch25 » 14 Jan 2020, 22:12

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
You can't have too many antennas...

barefootindian
Regular
Regular
Posts: 86
Joined: 30 Dec 2011, 17:56
Call Sign: 29SC01
Location: an dubh linn

Re: RF Coaxial Cable

Post by barefootindian » 15 Jan 2020, 23:02

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.

User avatar
ch25
Radio Addict
Radio Addict
Posts: 730
Joined: 03 Dec 2016, 11:07
Call Sign: Lemmy
Location: Poland

Re: RF Coaxial Cable

Post by ch25 » 15 Jan 2020, 23:27

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.
Chris
You can't have too many antennas...

User avatar
Mitch
Super Member
Super Member
Posts: 409
Joined: 02 Nov 2012, 21:26
Location: Leicestershire UK

Re: RF Coaxial Cable

Post by Mitch » 16 Jan 2020, 10:17

Can you set your radio up on the hill and just run a power cable to the house? I'd be cheaper.
The perfect face for radio.

barefootindian
Regular
Regular
Posts: 86
Joined: 30 Dec 2011, 17:56
Call Sign: 29SC01
Location: an dubh linn

Re: RF Coaxial Cable

Post by barefootindian » 16 Jan 2020, 13:42

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
Regular
Regular
Posts: 86
Joined: 30 Dec 2011, 17:56
Call Sign: 29SC01
Location: an dubh linn

Re: RF Coaxial Cable

Post by barefootindian » 16 Jan 2020, 13:45

Thanks for the answer Mitch

grafter
Radio Addict
Radio Addict
Posts: 726
Joined: 05 Oct 2007, 06:31

Re: RF Coaxial Cable

Post by grafter » 16 Jan 2020, 14:24

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
Regular
Regular
Posts: 86
Joined: 30 Dec 2011, 17:56
Call Sign: 29SC01
Location: an dubh linn

Re: RF Coaxial Cable

Post by barefootindian » 16 Jan 2020, 14:34

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
Regular
Regular
Posts: 86
Joined: 30 Dec 2011, 17:56
Call Sign: 29SC01
Location: an dubh linn

Re: RF Coaxial Cable

Post by barefootindian » 16 Jan 2020, 14:41

grafter I never thought of Westflex 103, but I'll consider that. Thanks for your input too.

Post Reply