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TOPIC: COAX

COAX 2 months 5 days ago #507

  • M3VSW
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hi folks, ok Radio looks ok, so back to my original issue, having run 2 new runs of coax to bottom of garden, I get high SWR across both, having redone end conenctors several times, Im confident its not that, its 7d-fb 50Ohm now they are quite long 50 metres, I could cut them down maybe 10 metres, but if that not going to help its a waste of long coax, any ideas ?

Cheers !
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COAX 2 months 4 days ago #508

  • M0NKR
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use a multi meter to check continuity of the coax, multi meter need to be set to Ohms. it should go to zero if cable is fine or a tine if you have a meter with that, go pin to pin, outer to outer you should get zero if cable is good, then go pin to outer you dont want zero on that.

What is the antenna on the end of the coax, that may need tuning.

73
M0NKR
73

Andy
M0NKR
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COAX 2 months 4 days ago #509

  • g0lgj
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Put a Dummy load on the remote end and try this. Seems strange both runs are doing it ?
Also check what you are measuring it with ? Do you have an antenna analyser ?
Mark G0LGJ
Mark Taylor G0LGJ
Tel 01362 691099 18:00 - 22:00
www.g0lgj.co.uk
www.norfolkamateurradio.org Norfolk Amateur Radio Club
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COAX 2 months 4 days ago #510

  • G0KYA
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What do you have on the other end of the coax? If it is an antenna are you sure it is fine and offering a low SWR on the band in question? A dummy load on the far end is the best way forward. And what meter are you using?

The fact you have a problem with both runs sets alarm bells ringing!

Steve G0KYA
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COAX 2 months 1 day ago #511

  • M3VSW
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Hi all,

ok thanks for replys, yes I have 2 new runs, both 50 meters long, I've been testing with a Dummy load on the end, so "should" be OK, not got a antenna analyzer, though do need one, so any recommendations gratefully received : )
So my only thoughts were the spec of this 7d-fb cable... anyone else using it ? Im correct in my belief that whilst a longer run will loose output power the SWR wont change regardless of length ? ( obviously assuming no shorts etc etc )

thanks
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COAX 2 months 1 day ago #513

  • M0NKR
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Looking at the specs of the cable, it wast the best choice, especially running at those distances for HF.

I would probably go for something like RG213, Eco flex or similar.

Technically if youve a dummy load on the end and the cable is terminated correctly you should see a good SWR 1.1. so no idea why your not.

Id suggest buying some new cable which is avilable from the club and we could terminate the end for you and go from there.

73
Andy
M0NKR
73

Andy
M0NKR
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