| Author |
Message |
    
Digger
New member
Username: Digger
Post Number: 3
Registered: 2-2004
| | Posted on Thursday, February 19, 2004 - 9:10 am: | 
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I can gain about 600' elevation with about 1000' of coax . My question is would it be worth the extra height or would there be to much lose?
Digger |
Ozzie
Member
Username: Ozzie
Post Number: 98
Registered: 11-2003
| | Posted on Thursday, February 19, 2004 - 9:40 am: |
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DONT!! Work out the loss on the coax cable. RG-8 has about 1db loss per 100feet at 30MHz. So at 1000ft thats 10db loss om both transmit and receive signals. That meas that if you put 100w into the cable about 10w makes it to the other end. Now depending on the antenna your ERP is about 15 (vertical) - 100w (large yagi or quad). So what have you gained??
Yes the height would be nice but the coax loss may not make it worth it. NOw if you can remote the radio and have it under the mast at 600ft - now that would be worth it. |
Kiwikid
Junior Member
Username: Kiwikid
Post Number: 121
Registered: 1-2003
| | Posted on Thursday, February 19, 2004 - 1:42 pm: |
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Hi Team,Digger you could run twin open feeder line or "ladder" line.Check out the "CB Bible" i.e. ARRL Handbook.This feeder has virtually no losses.This system is used in the commercial sector for shortwave and broadcast stations.You will need to have a balun at the radio end and the twin open feeder could be home brewed out of two lengths of wire and UV resitant nylon or plastic spreaders of about 4" long.A CB operater in my county had a station set up with this feeder to a elevated site and he boomed out.
73
Kiwi Kid
CEF 195
Hamilton
North Island
New Zealand |
Mikefromms
Junior Member
Username: Mikefromms
Post Number: 97
Registered: 6-2003
| | Posted on Thursday, February 19, 2004 - 6:26 pm: |
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Even with the RG 8 I think it would be worth it. 10 watts up that high would travel much farther then 100 watts 600' lower. But get some better coax.
mikefromms |
Digger
New member
Username: Digger
Post Number: 4
Registered: 2-2004
| | Posted on Thursday, February 19, 2004 - 7:17 pm: |
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Thanks guys for the input i guess i can put my spair beams on a tower and just back my truck up to it and turn with a handcrank, would this be a better idea?
Digger |
Hornet168ky
Junior Member
Username: Hornet168ky
Post Number: 69
Registered: 10-2003
| | Posted on Thursday, February 19, 2004 - 9:28 pm: |
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Or if you could find some "hard line" They use it quite often around here, they tell me it has vertuially no loss at all. IF you can find it, it is hard to find around here and when you do find it, whoever has it usually knows what they have and they price it accordingly.
Be safe!
Hornet |
Ozzie
Member
Username: Ozzie
Post Number: 99
Registered: 11-2003
| | Posted on Friday, February 20, 2004 - 9:25 am: |
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Mike,
YOur forgetting the loss on recieve signal too. Thats the main reason I dont believe it a good idea.
The truck idea sounds better than running that amount of cable. |
Digger
New member
Username: Digger
Post Number: 5
Registered: 2-2004
| | Posted on Friday, February 20, 2004 - 11:49 am: |
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Thanks gents, ithink i'll just do it with the truck. But thanks again
Digger |
Tech833
Moderator
Username: Tech833
Post Number: 565
Registered: 8-2002
| | Posted on Monday, February 23, 2004 - 2:21 am: |
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Digger-
Yes, it would make a big difference in your signal received as well as transmitted. Your takeoff angle would be greatly improved. Just look what Ham CBer did with that little milliwatt beacon in California! Takeoff angle is everything.
You would need to purchase some Heliax (often mistakenly referred to here as 'hardline'). I would say 1/2 inch Heliax is the bare minimum. 7/8 would be better.
I have run many 1000 ft.+ runs of Heliax. Given how low the 27 MHz. frequency is, the loss is minimal. |
Ozzie
Intermediate Member
Username: Ozzie
Post Number: 104
Registered: 11-2003
| | Posted on Monday, February 23, 2004 - 10:02 am: |
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Tech833 yeah but how many of us can afford 1000ft of heliax let alone the plugs?? Ive used it in the past commercially but not many hams or CBers can afford that cost. Heck the one thing I regret is not being able to bring from Australia was 200ft of 7/8" heliax with plugs - use to use it on my 2m antenna.
I am not trying to be funny but although your suggestion is correct technically, I feel answers should be kept to those sollutions that the general populace can afford, which is why I did not suggest that in my original answer to the question. |
Digger
New member
Username: Digger
Post Number: 8
Registered: 2-2004
| | Posted on Tuesday, February 24, 2004 - 9:09 am: |
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I have a solution .my better half ( the boss) said it would be cheaper to build a 12*12 building And move my equipment up there .doing this i can go to 1800'. but will have to use solar cells, deep cycle battery's and an inverter. would this be feasable and how big an inverter would i need ? |
Ozzie
Intermediate Member
Username: Ozzie
Post Number: 107
Registered: 11-2003
| | Posted on Tuesday, February 24, 2004 - 9:33 am: |
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THis is not much different from a repeater site layout. Question why an inverter?? if everything runs off of 12vdc no inverter required. However if you really need one total up the AC current for everything running off of 110VAC. Add at least 20% and that should give you a pretty good idea of the size needed.
Now from past experience I would recommend splitting the current draw into at leat two groups of fairly equal range and running one battery group, solar panels and inverter for each group. This way no one battery, panel or inverter is getting excessive draw from it. Whenever I have buitl solar powered repeater sites (mostly for Emergency Services) I have always followed this route and have never yet had a repeater site go down from power problems no matter what has been happening locally. I usually make sure that the battery pack could run the site for at least a week with no cahrging. Of course your case probably doesnt need that sort of overkill but give yourself some leeway.
If you need or want more information my email is clowes@bmi.net |
Digger
New member
Username: Digger
Post Number: 9
Registered: 2-2004
| | Posted on Tuesday, February 24, 2004 - 11:36 am: |
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They done a remodel on the local hospital and i had part of the grading contract, they changed out all the backup batterys,said i could have them if i want them(to keep them from paying for desposal)would this be doable as far as solar charging or is it the wrong voltage. i already have 2 3000 watt inverters out of my servie truck(where i upgraded)that are almost new.
Digger |
Lowpowerhal
Intermediate Member
Username: Lowpowerhal
Post Number: 147
Registered: 7-2003
| | Posted on Tuesday, February 24, 2004 - 8:36 pm: |
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Ok i have a coax ? Last summer they was replacing coax for cable tv in our town splitters and tranfomers, I got what was left of some coax on the spool. About 130 or so feet of it. Now my question what is it. I will decribe it for you. Outside coax is made of aluminium around 3/4 dia.foam inside with around number 9 copper wire center.Can anyone tell me about this coax. How many ohms or loss.Kinda like to know.Can it be applied to transmitting? I do understand this is recive line only but i wonder if you can put say 5 watts at 100 feet into this line? The foam thats is incased is not like the hard poly that is in rg58 or rg59. The foam that in it is like that exspansion foam that is used in insulations but has a little more density.Can anyone tell me about this coax???? |
The ELCO guy (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, February 25, 2004 - 8:22 am: |
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Subject, long runs of coax.
833 is right. If you will check the db loss tables on the coax charts as stated in loss per 100 feet you will note a significant loss with the use of coax when used in very long lenghts. This loss is a two way street in that the loss happens on both the outgoing and incomming signals.
For long lengths of coax use as suggest "Hard Line" aka heliax for use. HOWEVER be aware that the cost of heliax is very defnately not cheap and the connectors are equally expensive. In addition they stuff does not bend very well either--no sharp turns please.
For very long lengths use 450 ohm ladder line as an alternative to heliax. The losses are small. However as with heliax there are certain precautions that you have to take. First and most importantly you WILL REQIIRE a tuner to make our radio happy--450 ohm transmission line does not exactly make most modern CB transmitters happy without a tuner. Second, you will have to keep the ladderline away from metal objects, including the tower. Standoffs will be required. On the bright side, ladder line handles SWR a great deal better than coax transmission line. When buying your ladder line consult your dealer for installation procedures or get a copy of the ARRL handbook and read on the various ladder line topics in it.
Good Luck
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Ozzie
Intermediate Member
Username: Ozzie
Post Number: 108
Registered: 11-2003
| | Posted on Wednesday, February 25, 2004 - 8:58 am: |
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Yes sure can - its 75 ohm very low loss and with a bit of work using a hacksaw, aluminium tubing and a couple of hose clamps it can be made to work with PL_259 - have a length running my 2m vertical. Give me a chance to locate the information on putting PL-259s on to it and I'll email it to you. You could try plgs for heliax but I'll warn you they are not cheap. |
Charliebrown
Junior Member
Username: Charliebrown
Post Number: 27
Registered: 10-2002
| | Posted on Wednesday, February 25, 2004 - 10:12 am: |
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hello, my freinds here use this line for more than 1 thousand foot runs. this is 75 ohm cable and it can handle 1kw easy. to make this work they put 25 feet of coax at each end of the cable. you can use different lengths of coax but, what ever length you use at one end you will need to have the same on the other end. now the swr runs about 1.1 or less. if it is higher than 1.1 adjust the coax lenth at the radio end of the cable. s loss is extremly low on this cable. the only problem with this cable is the solid shield, if you bend this cable it will kink an break the outer shield. if you use this cable and need to splice this cable i can tell you later how they do it here with out the normal splice connection the cable company uses. i hope this will help you. |
Digger
Junior Member
Username: Digger
Post Number: 10
Registered: 2-2004
| | Posted on Wednesday, February 25, 2004 - 9:36 pm: |
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Thanks for all the good info, I thought i had the sulotion with the beams on the tower and using the 4x4 but i think i need some more research for later on, So thanks again.
Digger
CEF 308 |
