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#1
May 11th 05, 01:11 AM
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RF Grounding and Shorting a G5RV for use on 160 Meters
I'm thinking of tossing up a G5RV and perhaps using it at times on 160
meters by shorting the braid and center conductor. What do I need for buried radials ? Will several 40' - 50' radials work satisfactorially or would one ~125' radial be best ? I could run a 125' radial but not in a straight line I'm planning on using No. 14 Ga solid insulated wire. I think I've read in this newsgroup that the buried wire doesn't have to be bare ? Also does anyone have a more elegant way of shorting the inner conductor and braid together than the half axxed contraption I'd cobble together  ?Thanks in advance. Gary |
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#2
May 11th 05, 02:39 AM
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Gary wrote:
I'm thinking of tossing up a G5RV and perhaps using it at times on 160 meters by shorting the braid and center conductor. What do I need for buried radials ? Will several 40' - 50' radials work satisfactorially or would one ~125' radial be best ? I could run a 125' radial but not in a straight line Several shorter radials will definitely be better than a single long one. I'm planning on using No. 14 Ga solid insulated wire. I think I've read in this newsgroup that the buried wire doesn't have to be bare ? Yes, that's correct. Also does anyone have a more elegant way of shorting the inner conductor and braid together than the half axxed contraption I'd cobble together ?It's hard to say how to make something better than something for which we have no description. Surely it can't be too hard to short two conductors together. Roy Lewallen, W7EL |
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#3
May 11th 05, 07:25 AM
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On Tue, 10 May 2005 18:39:16 -0700, Roy Lewallen
wrote: Gary wrote: I'm thinking of tossing up a G5RV and perhaps using it at times on 160 meters by shorting the braid and center conductor. What do I need for buried radials ? Will several 40' - 50' radials work satisfactorially or would one ~125' radial be best ? I could run a 125' radial but not in a straight line Several shorter radials will definitely be better than a single long one. I'm planning on using No. 14 Ga solid insulated wire. I think I've read in this newsgroup that the buried wire doesn't have to be bare ? Yes, that's correct. Also does anyone have a more elegant way of shorting the inner conductor and braid together than the half axxed contraption I'd cobble together ?It's hard to say how to make something better than something for which we have no description. Surely it can't be too hard to short two conductors together. Roy Lewallen, W7EL Thanks Roy, I can certainly short two conductors together. I was just thinking of minimizing any amount of stray RF that might arrise given my propensity to make Rube Goldberg type contraptions out of something that should be an easy task. Gary |
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#4
May 11th 05, 03:06 PM
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On Tue, 10 May 2005 18:39:16 -0700, Roy Lewallen
wrote: Gary wrote: I'm thinking of tossing up a G5RV and perhaps using it at times on 160 meters by shorting the braid and center conductor. What do I need for buried radials ? Will several 40' - 50' radials work satisfactorially or would one ~125' radial be best ? I could run a 125' radial but not in a straight line Several shorter radials will definitely be better than a single long one. I'm planning on using No. 14 Ga solid insulated wire. I think I've read in this newsgroup that the buried wire doesn't have to be bare ? Yes, that's correct. Also does anyone have a more elegant way of shorting the inner conductor and braid together than the half axxed contraption I'd cobble together ?It's hard to say how to make something better than something for which we have no description. Surely it can't be too hard to short two conductors together. Roy Lewallen, W7EL One question, if shorting the leads to feed the g5rv "marconi style", would it be better to connect the single wire to the antenna tuner's random wire connection, or to the coax connection, or does it matter? bob k5qwg |
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#5
May 11th 05, 03:06 PM
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Hi,
Say, I've got a question about something I've read about the Swift gamma ray detection satellite. It's detector consisted of an antenna composed of 52,000 lead blocks arranged by computer generated pseudo-random locations and glued to the back of a sheet of 4x8 plywood. The actual detectors where located in the spaces between the blocks. It wasn't mentioned but I think these were probably crystals which give off a pulse of electricity every time they are struck by a gamma ray. Anyways my question is, in your opinion, what is the purpose of the pseudo random arrangement of this "apperture mask" antenna? I suspect it has something statistical related to the nature of ambient noise signals. I tried making a pc simulation of this but I get the same answer whether the array is in rows or pseudo-random. I tried with noise but I saw no reduction. I haven't tried adding a signal to the noise in the simulation yet though... A*s*i*m*o*v .... Three types of lies: lies, damn lies, and statistics - Mark Twain. |
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#6
May 11th 05, 04:02 PM
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It's hard to say how to make something better than something for which
we have no description. Surely it can't be too hard to short two conductors together. Roy Lewallen, W7EL One question, if shorting the leads to feed the g5rv "marconi style", would it be better to connect the single wire to the antenna tuner's random wire connection, or to the coax connection, or does it matter? bob k5qwg How much current will actually flow in the center conductor of the shorted coaxial feedline? The single wire connection makes much more sense. I never liked the G5RV antenna since it just seemed like a high loss method of feeding a 102 ft piece of wire. Frank VE6CB |
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#7
May 11th 05, 04:10 PM
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What is the basis of your "high loss method" statement?
"Frank" wrote in message news:O7pge.61496$tg1.25181@edtnps84... I never liked the G5RV antenna since it just seemed like a high loss method of feeding a 102 ft piece of wire. Frank VE6CB |
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#8
May 11th 05, 04:58 PM
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"Fred W4JLE" wrote in message ... What is the basis of your "high loss method" statement? "Frank" wrote in message news:O7pge.61496$tg1.25181@edtnps84... I never liked the G5RV antenna since it just seemed like a high loss method of feeding a 102 ft piece of wire. Frank VE6CB The following is based on an analysis I did for a ham Friend. Consider a 102 ft bent dipole (REF: Richards Antenna v4), fed in the center with 33ft of 300 ohm tubular, followed by 25 ft of 75 ohm twin. Frequency Total feedline loss (MHz) (dB) 1.8 24.8 3.8 4.9 7.1 2.4 10.1 10.2 14.1 1.4 18.1 3.0 21.2 9.1 24.9 2.7 28.5 3.9 If you are interested I can e-mail you the complete analysis in Microsoft Word showing various feedline combinations from 1.8 to 30 MHz. If you have a particular structure in mind I can also do the analysis. I use NEC2 based software in combination with the ARRL's transmission line analysis program. Regards, Frank VE6CB |
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#10
May 11th 05, 06:14 PM
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"Fred W4JLE" wrote in message ... Frank, with all due respect I disagree with your analysis. I would appreciate your sending me the data so we may both start at the same discussion point. will get the info to me. 73 Fred Thanks Fred, I am happy when people disagree with me, since then I have a chance of learning something. I will e-mail you my analysis. 73, Frank |
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