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 ladder feed 
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Will running ladder feed in trunking effect its performance ?

John (m6jms)


Mon Apr 06, 2015 10:31 am
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Post Re: ladder feed
M6JMS wrote:
Will running ladder feed in trunking effect its performance ?

John (m6jms)

Plastic or metal?
And also what is the trunking mounted on/next to?
Idealy ladder line needs to be as much as is practicaly possible in free space, bringing it near any conductive mass, over a reasonably large length, will affect its performance!
One of the reasons people use co-ax runs where close by conductive structures/masses are unavoidable!

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Mon Apr 06, 2015 10:39 am
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If it's standard electrical trunking then it is probably fine as it is pretty good insulator for RF, as Dave says, be careful what is behind the trunking, especially against walls where there might be other services buried. The other thing to remember, if it is run near to electrical services you might get additional noise pick-up.

I used to have 450 Ohm feeder strapped against my 9Mtre fibre glass pole and just replaced it with home made open wire line and can't notice any difference at all in the tuning if that helps.

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Mon Apr 06, 2015 10:52 am
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Thanks for the info. The trunking is plastic and runs down a upvc window frame before the feed will enter the room through a drilled hole. I won't know until I try it.

Thanks again

73's John


Mon Apr 06, 2015 2:08 pm
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John,

Be careful the window frame hasn't got metal inside it, some do.

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Mon Apr 06, 2015 2:27 pm
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I have 300 ohm nearly touching a brick wall in places and then it is against the uPVC window frame and comes through the window frame in a hole, no metal in that part and it is working fine. You should be fine taking the advice above.

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Dennis


Mon Apr 06, 2015 7:31 pm
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 ladder feed 
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Great help - thanks to all who contributed and for the use of the site.

73's John M6JMS


Wed Apr 15, 2015 11:40 am
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Post Re: ladder feed
There's some related information on my web site about what happens to ladderline when it gets wet, lays in contact with the ground, touches metal, etc, which you may find interesting:

http://www.karinya.net/g3txq/wet_ll/

Steve G3TXQ


Wed Apr 15, 2015 12:30 pm
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 ladder feed 
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Thanks Steve I will have a look.

73 JOHN


Thu Apr 16, 2015 8:50 am
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