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#1
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1/4 Wave on 28.500MHz
I have a stainless steal 1/4 wave length mobile whip.
Can I mount this on top of a 20ft aluminium scaffold pole and use the pole as the ground radial? I also have a mobile AM-80 for 80 meters. Can I mount this in the same way and will it work ok? Thanks |
#2
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1/4 Wave on 28.500MHz
On Thu, 17 Apr 2008 16:09:10 +0100, "Barrett"
wrote: I have a stainless steal 1/4 wave length mobile whip. Can I mount this on top of a 20ft aluminium scaffold pole and use the pole as the ground radial? I also have a mobile AM-80 for 80 meters. Can I mount this in the same way and will it work ok? Hi Barrett, The combination will give you an offcenter, vertical dipole (for either band you are investigating). This is not a bad thing, just something that may not tune up the way you think it "should." The 10M application will have three sections: 1. The quarterwave whip; 2. a 5/8ths wave lower section (the pole); 3. an undefined length of transmission line (unless you choke it). 73's Richard Clark, KB7QHC |
#3
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1/4 Wave on 28.500MHz
Thanks Richard
"Richard Clark" wrote in message ... On Thu, 17 Apr 2008 16:09:10 +0100, "Barrett" wrote: I have a stainless steal 1/4 wave length mobile whip. Can I mount this on top of a 20ft aluminium scaffold pole and use the pole as the ground radial? I also have a mobile AM-80 for 80 meters. Can I mount this in the same way and will it work ok? Hi Barrett, The combination will give you an offcenter, vertical dipole (for either band you are investigating). This is not a bad thing, just something that may not tune up the way you think it "should." The 10M application will have three sections: 1. The quarterwave whip; 2. a 5/8ths wave lower section (the pole); 3. an undefined length of transmission line (unless you choke it). 73's Richard Clark, KB7QHC |
#4
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1/4 Wave on 28.500MHz
Just went out to get things ready to try the Ariel's out tomorrow and it
occurred to me that the 20ft pole is resting on the patio. To make this work, would I need to lift the pole off the floor and would 1ft be enough? Thanks "Barrett" wrote in message ... Thanks Richard "Richard Clark" wrote in message ... On Thu, 17 Apr 2008 16:09:10 +0100, "Barrett" wrote: I have a stainless steal 1/4 wave length mobile whip. Can I mount this on top of a 20ft aluminium scaffold pole and use the pole as the ground radial? I also have a mobile AM-80 for 80 meters. Can I mount this in the same way and will it work ok? Hi Barrett, The combination will give you an offcenter, vertical dipole (for either band you are investigating). This is not a bad thing, just something that may not tune up the way you think it "should." The 10M application will have three sections: 1. The quarterwave whip; 2. a 5/8ths wave lower section (the pole); 3. an undefined length of transmission line (unless you choke it). 73's Richard Clark, KB7QHC |
#5
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1/4 Wave on 28.500MHz
Barrett wrote:
Just went out to get things ready to try the Ariel's out tomorrow and it occurred to me that the 20ft pole is resting on the patio. To make this work, would I need to lift the pole off the floor and would 1ft be enough? Depends on whether the patio is conductive or not. Probably best to rest the base on an insulator. Also be aware that, at 100 watts, there will be hundreds, if not thousands of volts present at the base of the pole. I once keyed down while a cat was standing on one of my radials. Not sure where it went, but it might have gone into orbit. Have you considered sleeving the pole inside PVC pipe for safety reasons? -- 73, Cecil http://www.w5dxp.com |
#6
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1/4 Wave on 28.500MHz
On Thu, 17 Apr 2008 19:17:23 +0100, "Barrett"
wrote: Just went out to get things ready to try the Ariel's out tomorrow and it occurred to me that the 20ft pole is resting on the patio. To make this work, would I need to lift the pole off the floor and would 1ft be enough? Hi Barrett, Not something I would worry about. Others may, and they will certainly chime in if they do. I had a 10M vertical off-center dipole mounted about 1 foot above ground and it seemed to work fine; but not as well as my buddies with higher antennas. My guess is that an 80M version may suffer more. I fed the transmission line up through the bottom section. 73's Richard Clark, KB7QHC |
#7
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1/4 Wave on 28.500MHz
In message , Cecil Moore
writes Barrett wrote: Just went out to get things ready to try the Ariel's out tomorrow and it occurred to me that the 20ft pole is resting on the patio. To make this work, would I need to lift the pole off the floor and would 1ft be enough? Depends on whether the patio is conductive or not. Probably best to rest the base on an insulator. Also be aware that, at 100 watts, there will be hundreds, if not thousands of volts present at the base of the pole. I once keyed down while a cat was standing on one of my radials. Not sure where it went, but it might have gone into orbit. Have you considered sleeving the pole inside PVC pipe for safety reasons? A glass jar (eg a jam jar) makes an effective insulator for the base of a pole. Or a polythene bucket! -- Ian |
#8
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1/4 Wave on 28.500MHz
Ian Jackson wrote:
A glass jar (eg a jam jar) makes an effective insulator for the base of a pole. Or a polythene bucket! Remember when we used to use those one quart Coca-Cola bottles that down-spouts fit over perfectly? -- 73, Cecil http://www.w5dxp.com |
#9
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1/4 Wave on 28.500MHz
Cecil, got a question for you.
I have another 20ft pole mounted on the back of my house and it is rested on the patio floor. I plane to put up a Cushcraft MA5B on this pole and a 2/70 collinear on top. Does this mean that there will be high voltage on the pole beneath the beam from the beam or from the collinear? The children will be out in the garden when the weather gets better. Thanks "Cecil Moore" wrote in message ... Barrett wrote: Just went out to get things ready to try the Ariel's out tomorrow and it occurred to me that the 20ft pole is resting on the patio. To make this work, would I need to lift the pole off the floor and would 1ft be enough? Depends on whether the patio is conductive or not. Probably best to rest the base on an insulator. Also be aware that, at 100 watts, there will be hundreds, if not thousands of volts present at the base of the pole. I once keyed down while a cat was standing on one of my radials. Not sure where it went, but it might have gone into orbit. Have you considered sleeving the pole inside PVC pipe for safety reasons? -- 73, Cecil http://www.w5dxp.com |
#10
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1/4 Wave on 28.500MHz
Barrett wrote:
Cecil, got a question for you. I have another 20ft pole mounted on the back of my house and it is rested on the patio floor. I plan to put up a Cushcraft MA5B on this pole and a 2/70 collinear on top. Does this mean that there will be high voltage on the pole beneath the beam from the beam or from the collinear? Are the beam and collinear isolated from the pole? If so, there's probably no real problem. If a mobile antenna is being used with the pole as the counterpoise, then about half of the RF energy flows in the pole. RF burns can be the result. -- 73, Cecil http://www.w5dxp.com |
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