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Author Topic: Grounding of radial base plate  (Read 4261 times)
K2OWK
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Posts: 1042




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« on: August 15, 2012, 11:35:53 PM »

I am installing an LDG S9 antenna. I have the LDG antenna radial base plate. Is there any advantage to grounding (tying) the base plate to the antenna mounting pole (48" galvanized steel pipe) driven about 35" into the ground? This is the first time I am installing a vertical antenna of this type.

Thank you,

73s

K2OWK 
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KC4MOP
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« Reply #1 on: August 16, 2012, 04:24:13 AM »

I cannot find anything on-line about installing any S9 antennas. I'll assume that the radial plate just sits at the base, probably installed before you set the vertical element on the mounting post. Connecting the radial plate to that post will not do anything dramatic. You should drive the standard 6-10 foot ground rod close to the base. And then you will run out as many as you can, as long as you can, bare or covered, stranded or solid wires out the far end of your property. The "works for most Hams" formula is around 40-60 radials spaced evenly around the base of the antenna.
Is this the 43 foot vertical??? You did not mention what model S9.
IF it is the 43 footer, start saving for a Christmas present to yourself and get one of the high power remote tuners and locate at the base.

Fred
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K3GM
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« Reply #2 on: August 16, 2012, 06:55:30 AM »

I see no advantage to doing what you ask.  I am not familiar with your antenna, but you need to make sure there is a low impedance connection between the shield of the transmission line, and the radial plate. The DX Engineering plates have a nifty bulkhead mount on the plate which allows you to literally plug the shield of the transmission line directly into the plate via a bulkhead connector, then run a pigtail to the radiator. http://static.dxengineering.com/global/images/instructions/dxe-radp-3_rev0b.pdf I don't see something like that on the LDG plate, so if I were to use it, I'd get a small section of angle aluminum, drill a hole thru it that will accept a bulkhead connector, or and SO-239 connector and mount little piece of angle aluminum to one or two of the holes in the radial plate. Then you'll have a low impedance, direct connection to your transmisssion line.
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KB4QAA
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« Reply #3 on: August 16, 2012, 10:34:25 AM »

Advantages:
-Slight improvement in RF ground plane
-If the vertical radiator is DC grounded, a reduction in static charge and attendant noise, improvement in lightning safety.

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N4NYY
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« Reply #4 on: August 16, 2012, 10:56:03 AM »

Advantages:
-Slight improvement in RF ground plane
-If the vertical radiator is DC grounded, a reduction in static charge and attendant noise, improvement in lightning safety.



Good to know. FWIW, the 5BTV ask for a 4' pipe into the ground, which is connected to the ground radials. So, while not 8', it is still into the ground 4', and connected to the radials.
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W5WSS
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« Reply #5 on: August 16, 2012, 12:57:46 PM »

I would plug the shield directly into a bulkhead designed into a radial ring that incorporates  an so-239. I would use a wide strap from the tuner to the radial plate that is a good and reliable RF connection.
I would not go through the galvanized pipe IE not rely on that as a RF circuit for the radials to shield to coaxial connection.
weatherproof the connections to avoid corrosion.
a galvanized pipe within or between the junction of the return path via the radials is not stable electricall respective to Rf
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K2OWK
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« Reply #6 on: August 16, 2012, 03:12:21 PM »

Thanks for all the replies. I have the 32 foot S9 antenna and plan to operate it on 40 thru 6 meters if possible. The instructions on the radial plate say just set it on the ground with the center hole on the pipe and run a minimum of 16 radials of about 26 feet or so. I have enough wire (solid insulated copper) 500 feet to install about 18 or 20 radials to start with. I asked the question because some of the radial plates sold by other companies have a clamp to hold them to the mounting pipe. The plate I have does not have an SO 239 connection plate. It is just a flat aluminum plate with 20 pieces of stainless steel hardware to attach the radials to. I guess I could try it both ways and see which works best. Just for information, I am using an MFJ-914 Auto Tuner Extender with my internal tuner. This allows my internal tuner to tune a mismatch up up 10 to 1. I will be feeding a 4 to 1 UNUN at the base of the antenna.

Thanks again for your replies.

73s

K2OWK
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W5WSS
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« Reply #7 on: August 16, 2012, 06:06:05 PM »

Okfor the plate to be mounted on the pipe or at the ground centrally located and very close to the center of the feed point is the idea,
and not electrically including the pipe it is mounted too.
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N8CMQ
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« Reply #8 on: August 16, 2012, 06:16:13 PM »

I am installing an LDG S9 antenna. I have the LDG antenna radial base plate. Is there any advantage to grounding (tying) the base plate to the antenna mounting pole (48" galvanized steel pipe) driven about 35" into the ground? This is the first time I am installing a vertical antenna of this type.

Thank you,

73s

K2OWK 

I would bond the radial plate to the antenna mount rather than the pole sticking out of the ground, so the coax shield is grounded to the rf ground with the least impedance.
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K2OWK
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« Reply #9 on: August 16, 2012, 11:50:40 PM »

I may be reading this wrong, but the antenna mount is the pole sticking out of the ground. The antenna is a hollow fiberglass tube with a wire running through it that goes over the pole. The shield and center conductor of the coax goes to the 4 to1 UNUN via the  SO239 input. The output of the UNUN  center conductor goes to the S9 wire. The coax shield goes to the radial plate. I would run a heavy copper wire from the radial plate to a muffler clamp on the antenna mounting pole. This would tie the radial plate to the pole. I will try this with and without the plate tied to the pipe to see how it works. One last thing KC4MOP suggested I put in a grounding rod next to the antenna grounding plate. I would guess if I do this i would need to connect this rod to my main grounding system.

73s

K2OWK
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W8JI
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« Reply #10 on: August 17, 2012, 07:37:07 AM »

I'm going to throw a fly in the ointment.

Grounding the radial plate might..... or might NOT...... improve the RF ground.

If you have a sparse elevated counterpoise or insulated radial system, grounding the radials can actually make the ground system worse.

If you have a good system, it makes no difference at all in anything for signal and will barely change lightning behavior, and will not affect static or charge buildup at all.

I'm working on a counterpoise page:

http://www.w8ji.com/counterpoise_systems.htm

but it is very involved and is incomplete. If you read what is there so far, it clearly illustrates problems with earth connections when ground systems are small, or truncated.

If you have a reasonable size earth-based radial system, with radials in, on, or in contact with earth, that small addition won't do anything at all one way or another performance or safety wise, and neither will a ground rod.

If you have a smaller ground system, the only accurate answer is "it depends". 

If you install 20 radials 25 feet long on the earth or in the earth, a rod ground connection is totally meaningless for RF. An earth rod might be a slight advantage for lightning and electrical safety, because you have insulated wire. It won't reduce static, and it won't reduce chances of a lightning strike.  You also might speed physical deterioration of the mounting pole with electrolysis by tying it in, if the pole metal choice and other factors are wrong.

If you have a smaller ground system, especially one isolated from earth, a ground connection can reduce performance.

Frankly though, with a 32 foot vertical and a remote tuner behind a long length of coax, worries about efficiency on bands other than 40 meters are relatively minor. The antenna system will not be all that efficient because of matching method losses, and on 15 meters and higher a 32 foot tall vertical wastes a lot of energy at high angles. This does not mean you will not be happy or not make contacts, I'm just pointing out losses in the ground system are not as important because there are so many other additional losses.

The popular monopole one-length-fits-all non-trap verticals are not high performance systems, they are just easy antenna to build.

73 Tom

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