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Author Topic: Radial wire guage.  (Read 972 times)
WA9CFK
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Posts: 98




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« on: March 06, 2013, 01:15:45 PM »

Depending on how ambitious I am, I plan to put down about 32 radials about 80 to 100 ft long for use on 160 meters. This is better than 2500 feet of wire.

I have read where gauge is not important for radials but I was wonderring just how small a gauge can be used. I passed on a 200 ft roll of intercom cable because it looked like each wire pair was 22ga. or perhaps 24 ga. wire. I did not want to waste the effort to peel and pull out all the cable wire pairs, if it was not going to work.

The wire insulation would keep each wire from rotting in the ground and I suppose I would never pump more than 200 watts into it; but would the small diameter or skin effect at that frequency be a problem?   
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KB4QAA
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« Reply #1 on: March 06, 2013, 01:49:00 PM »

The engineers tell us that for antennas wire as small as 28AWG is fine. 

I think the same is true for radials, especially since they aren't handling any power.   Bare, enamel, or insulated, are fine.  Radials do not need to be in contact with the soil.
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N4CR
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Posts: 1672




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« Reply #2 on: March 06, 2013, 02:20:08 PM »

The real problem with smaller gauge wires is that they are often solid core. They break easily after being flexed a few times and any tugging tends to pull small gauge wires away from the connection point.

A good source of lots of 22 gauge stranded wire is CAT-5 ethernet cable. No need to strip the wires, just strip the jacket.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
K0ZN
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Posts: 1553




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« Reply #3 on: March 06, 2013, 07:43:00 PM »

The ONLY issue is mechanical.  The current is divided between the wires and to some degree the ground.  32 radials of AWG 24 would be fine at legal limit....
at 200 watts they are not even going to get out of bed to see what is happening !

I have personally put down over 200 radials in two vertical antenna systems. Based on what I have seen, simply for mechanical integrity, I would probably recommend
# 16 solid copper wire (or 14 solid if money is not a big issue), but if you are absolutely SURE the wires won't be disturbed, stepped on, trampled by cattle, tractors or deer, kids on a dirt bike or ATV or mower, septic truck!... etc.  then smaller wire is probably fine. If you can actually bury it an inch or so, a lot of problems go away, but that is another project. To me, the minimum would be #18, simply for strength. I used # 14 bare solid copper in my radial systems and it has essentially been bullet proof including
kids on 250cc motocross bikes riding over the radials ! FYI: leave a LITTLE extra slack up near the base of the antenna as the earth DOES move with moisture
and seasonal change and seems to tighten the wires a little over the years.

Copper wire will last for YEARS and years in the soil unless you have a very acidic soil. Do NOT use steel or galvanized wire; at some point it will rust and rust is a terrible
conductor at RF. Aluminum would be OK but don't expect the life of copper and you need to take care of the dissimilar metal connections to prevent
galvanic corrosion. Bottomline:  Copper is easily the best choice.

73,  K0ZN
« Last Edit: March 06, 2013, 07:50:04 PM by K0ZN » Logged
KC4MOP
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Posts: 743




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« Reply #4 on: March 07, 2013, 03:30:11 AM »

The real problem with smaller gauge wires is that they are often solid core. They break easily after being flexed a few times and any tugging tends to pull small gauge wires away from the connection point.

A good source of lots of 22 gauge stranded wire is CAT-5 ethernet cable. No need to strip the wires, just strip the jacket.
Great idea......thanks
I'll be looking for any scrap or surplus CAT 5. A lot of stripping of the jacket...makes for a summer project and some 807's
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K3GM
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« Reply #5 on: March 07, 2013, 04:23:16 AM »

Depending on how ambitious I am, I plan to put down about 32 radials about 80 to 100 ft long for use on 160 meters......

Let me offer a shortcut.  Once you determine the overal length of your wires. Get two wood stakes, and and pound them into the ground spacing them apart half the length of your radial length.  Take your spool of wire and fasten the free end to a screw or nail in one of the stakes.  Pay out the spool by walking 'round and 'round the stakes until the spool, or you is exhausted.  Cut each turn as it passes around the starting stake, and you've got radials of your deisre length.  Don't worry whether it's twisted pair or in a jacketed bundle.  Just strip and tie all the conductors in the bundle together at the ground point of the antenna.  While the majority of the radial in my field are insulated stranded 16AWG copper, I also have many hundreds of feet of hi-tensile aluminum electric fence wire.  While its lifespan is shorter than copper, they have lasted 4 years so far installed and pinned to the surface, although now mostly covered by field grass thatch.

Here's my radial "fixture": http://i9.photobucket.com/albums/a96/TwoSevenRight/cutting_radials.jpg
« Last Edit: March 07, 2013, 04:27:00 AM by K3GM » Logged
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