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Old 09-27-2011, 05:50 PM   #1
caymann
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Here's my current setup...

I bought a Eagle One antenna. It's a vertical antenna at 31'. I mounted this on the bike rack in the back of MH.

I also bought a ICOM AH-4 tuner that i put inside the engine compartment and connected to the antenna

The radio (ICOM 7000) stays inside the MH in the living room area and i ran the power/control cables + 50' of LMR400 coax w/PL259s, through the length of the coach.

The radio has a RF ground port.
The tuner has a RF ground port.
The antenna has a ground port.
I have a 4' ground rod.

How do i connect all these grounds to:-
1. help a path to lightning to ground using ground rod but not get into tuner/radio.
2. help the tuner with a RF ground to get better SNR
3. help the radio with a RF ground to get better SNR
4. avoid any RF interference inside the MH that affects any DC ckts or AC ckts.

My thinking is:-
1. Connect antenna ground to ground rod and hammer it into ground. I have a 400W lightning arrestor in line.
2. Connect tuner ground to ground rod and keep it less than 9'
3. don't connect radio ground to anything as it's ground is connected to tuner via coax
4. Optionally, connect ground rod to chassis ground so MH can act as counterpoise (this is highly debatable)


Any thoughts/comments?

thanks
jim
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Old 09-27-2011, 06:55 PM   #2
W5DOK
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Hi Jim,
Welcome aboard.
On my MH, I connect a 1 inch braid from antenna to mh frame. My Icom has a built in tuner so I don't have to do anything to it. I don't ground the mh to a ground. The mh frame acts as a good counterpoise. My antenna is a Tarheel 100A screwdriver or depending on my location, a Comet CHA250B. To keep rf out of the house, I keep the base of the antennas above the roof line. I have a 2 section telescoping pole that I cut both ends off of so that it fits nicely in a storage bay and just clears the roofline when extended. I attach it to the rear ladder and ground them both to the mh frame. This system works great for me. Never had a rf problem and talk to just about anything I can hear. Of course this system is not comparable to a tower and yagi, but it keeps me occupied. My Icom puts out 100 watts and that's all I work with.
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Old 09-27-2011, 08:20 PM   #3
caymann
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Hi Doc
Thanks for the reply.
Curious on what icom radio are you using?
How long is the coax feeding radio and the antenna?
The coax is likely unbalanced and hence radiating due to common mode current.
You could use a balun at the feedpoint, if not already using one.
If the tuner is at the antenna base then a balun is not needed.
Doing so, you may be able to increase your SNR on the radio end and hear
weaker signals and keep RFI out.

I am not sure if the antenna ground should be connected to the MH frame, which is why i put debatable in my post. Generally speaking, a counterpoise needs to be below the antenna, not to the side of it. So now the other half of the antenna is the MH frame and all kinds of RF is flowing through it. At least that is what i am thinking.
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Old 09-27-2011, 08:24 PM   #4
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I use a hamstick dipole to avoid groundplane issues. Your electrical grounding plan seems sufficient given that you're in an RV. WATCH OUT FOR UNDERGROUND ELECTRICAL SERVICE LINES when driving your ground rod in an RV park--also water and sewer lines. It is probably a good idea to get permission from the park management, which may, or more likely, may not be granted.
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Old 09-27-2011, 08:39 PM   #5
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The point about ground rod in a RV park is excellent.
I never thought about that permission. Thank you for that advice.
I figured, people put tent stakes (although only foot long max) so
i shouldn't have to worry about 4ft of ground rod....but now am rethinking.

This is my first setup and i haven't taken this to a RV park yet.
I am just trying it out at the driveway/home for now

I have been also thinking about rotatable dipoles as it
will outperform the vertical. I just don't like to go change the
band outside when it is raining. With a vertical, i am covered
80-10.... ok, i am being lazy
How high can you mount a dipole and rotate it?
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Old 09-28-2011, 08:43 AM   #6
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Jim, My rig is an IC736. Old, but reliable. I use about 50 ft of coax and it lays on the ground under the mh and enters thru a vent in front. My radio sits on the workdesk area in front of the co pilots seat. I like it simple and easy. I do have a balun at the antenna, but everything else is plug and play. Never had a rfi problem or any rf related issues inside the coach. I was recently in an rv park in Colorado with 2 other hams and my rig out performed theirs in every way. They were using an assortment of antennas that took hours to install and I was using a Tarheel that took 5 minutes to install. I checked with my neighbors and they experienced no interference from my rig, so I'm assuming everything was working correctly. There was a cb operator in there for awhile that managed to PO several folks with tvi, but he was asked to leave quickly. At my home QTH, I have several hundred acres to run whatever antennas I choose, but on the road I don't expect anything other than portable performance and I'm always surprised at the results I get.
Doc
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Old 09-28-2011, 08:41 PM   #7
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I use a 30' push-up pole and rotate it manually when necessary. I operate mostly 20m for PSK-31 but I have fun on phone as well. Regarding grounding, I don't, but if you need to, you might consider grounding to your water pipes. It's a compromise, but better than nothing and safer than a ground rod in an RV park.

BTU OM,

73 de KE5ZRT, dit dit
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Old 09-28-2011, 09:08 PM   #8
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A Twitter and ham friend of mine, Charles Blackburn, WX4CB, shared the following on Twitter after I shared a link to this thread:

@wx4cb: @Chris_Seright one thing that you can use for grounding.. those corkscrew shaped dog stakes... work well for me when im in the park
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Old 09-30-2011, 12:12 PM   #9
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I used #10 wire from the Tuner to the frame, and for those occasions when I have no electrical ground it goes on to a 3' screwdriver I can push into the ground.

Not the best ground, but better than nothing.

NOTE: yes, this does leave me with a possible loop, (rig/frame/tuner/coax) but if I see evidence of issues in that area.. I will figure out how to isloate one or the other of those (Rig/Tuner)
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Old 10-06-2012, 12:28 PM   #10
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For portable operations (& camping) we use a surface wire grounding kit, what is driven into the ground depends on ground type (and permissions I guess!).

1. Coax passed through a "Alpha Delta UHF Connector Coaxial Cable Surge Protector" mounted on a copper grounding plate. If I *can* drive a grounding rod I have the U clamp thingy, else a simple (cheap) flat copper plate.

2. From the copper plate I run 3x 8ft long 6-8gage (can't remember which, thick) bare copper grounding wire, and about every 2-3ft along the wire there is a 10" tent peg (steel !) connected. These are driven into the ground. They usually can't complain about driving tent pegs in the ground.

This wire assembly rolls up and gets stuffed into a bag - pretty compact and ready-made.

3. Depending on ground quality, dig a shallow hole to "bury" the tent peg, and water the hole.

4. There is a grounding strap from the copper plate to the radio and tuner.

5. Found a youtube video of a commercial version. Mine uses tentpegs from Walmart ...


Tim/KQ1Y
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Old 10-06-2012, 04:53 PM   #11
N3LYT
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A single point ground is the best, I use a ground lug bolted to the frame of the camper the power cord to the electrical box is probably a better ground then any thing short of an 8' ground rod the wire it's at least a #10. I went all over the camper with a mega ohm meter and made sure every thing was bonded together (aluminum siding and roof) and grounded all of that to the single point ground a long with the radio and tuner. I'm using a 706G and a lil tarheel bolted to the side of the frame work on the roof I run my feed line and control wire for the antenna through a compartment and up to the table inside.
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Old 10-06-2012, 06:34 PM   #12
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A ground rod, whether 8' long or 80' long, is a really miserable RF ground -- effectively it's not a ground at all at RF, though it may be minimally useful for DC or for 60 Hz if you need a ground for those.

But if you feel you must have something driven into the ground, it's much easier (and quieter) to do what I do: I use an assembly of fittings from Home Depot to attach a water hose to the end of a 5' or 10' piece of inch-and-a-quarter pipe; turn on the water; stand the pipe up; and watch it sink into the ground by its own weight. It works in most kinds of soil, though not all. I don't do this for a ground, though; I do it in order to have a pipe sticking out of the ground to mount antennas on.
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