Vertical HF antenna on motorhome

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fulltimer bob

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Dec 3, 2007
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I'm in the process of setting up a 30-foot telescoping pole attached to the rear ladder with a 14-gauge long-wire wound around it and feeding it with an AH-4 Tuner.  I have the tuner mounted at the base of the ladder.  I was wondering about the grounding of the darn thing.  I have the ground lug of the Tuner attached to the motorhome frame.  Obviously I'm only using this while parked.  I'm wondering if I should ground the rig with a temporary ground rod?  If possible a short rod driven down into the ground as far as is feasible with the idea of pulling it back out when moving on.

I've read some information on this and their seems to be a problem with ground loops, RF problems with RF getting back into all kinds of other equipment.

Any ideas on this?
 
This is from a buddy who has used the Ah4. 

The AH-4 is very prone to RFI.  Tried one and hated it for that reason.  I'm using the SGC very successfully.

  Short ground rod is better than nothing, but in the campground you must be certain you're not driving into the water or AC feeds, which are everywhere.  There is some info out there pertaining to laying a flat plate on the ground (like a pizza box) to facilitate a decent ground.  Might be worth looking into and will not bother the neighbors with hammering.

  I have been using the SGC at the center of a dipole for the last several years and it is the best portable dipole I have ever used.  One leg of the dipole goes to the output of the tuner, the other to the ground lug.  Works like a champ and tunes everywhere every time.

  If this guy is willing to have a 30 foot pole, maybe he should set up a screwdriver antenna and use the RV chassis for the ground.  My guess is it will outperform a 30 foot random wire every time.

  SEE YA!!
 
Many parks will not allow anything to be driven into the ground as the TV cables and electric wiring are there as well as the water and sewer lnes.  I KNOW they are supposed to be buried per code but I can tell you that they are often not that way.  The lines in my stick house lot are much shallower than code.  Fortunately the water and sewer information is on my lot plan so I can keep things out of the lines from the well and to the septic tank.  On the others, it is anybodies guess how deep and where.  Even the locator service isn't sure and the TV cable installation cut a power lne next door to me. 

I have just grounded my antenna to the frame and hope for the best.  So far no problems that I haven't been able to solve using good practice.
 
I've done some HF mobile from a minivan and a pickup truck, haven't tried the motorhome yet. You may indeed have issues with grounding, to me it seems one of the more challenging parts of the installation. Even a screwdriver antenna (as has been suggested) will need a good ground.

One problem you may find is that the various large metal parts of the MH may not be very well connected. You may have to run jumpers between things to cure this. I have had to do this on a small scale in the minivan, e.g. running a jumper from the bumper to the frame, and from the sheet metal around the driver's door (near where I had a screwdriver antenna mounted) to the frame members underneath.

Experimentation is the key, as far as I know.

One suggestion I have for "fixed" operation (not driving) is that you can lay a counterpoise wire of whatever convenient length on the ground. It doesn't necessarily have to go in a straight line, and it can be fairly small wire. I've used this kind of thing for temporary locations, you could hold it down with "staples" made out of lengths of wire bent into a U shape and pushed into the ground, or just lay it out. You do have to be careful about people tripping in it if it's in an area where folks may walk. You could lay it out at night and pull it in in the morning.

Good luck! DE N7GGJ
 
Good comment.  I haven't used it on the ground but have on the roof of my dad's trailer and in hotel rooms.  I may do ths on the roof of the MH when I mount my Shakespeare multiband up there.
 
I have about a 3 foot rod I can shove in the ground as needed... I use multiple wire antennas

Suggestion.. A slinky can streatch to 15 feet, but I'd coat it with liquid electrical tape or some othe flexible paint after pulling it out to 10 foot or so.

As of yesterday they still sold them in stores. brand new.
 
I've been using a 31' Jackite Pole Mounted to the ladder with an AH-4.

I've used a combination of grounding to the frame, a dog stake, and radials.  One under the trailer and one out back.

Home Depot sells "lawn stables" to control the radial on grass.

I bought a 5' whip.  Cut the end off the top section of the Jackite pole and used about 2' of the whip to get to 33'.

With the pole on the ladder, most of the rf is going into the rv frame.  I had the blue boy also on the ladder and used it as a spacer for the last few feet of antenna.

Of course a doublet is better if you can get it up.

Here's some pictures.
http://picasaweb.google.com/109144519583443207926/20100818RVsAndAntennasAtFourthCliff02?authkey=Gv1sRgCP6quv_3yY66gwE&feat=directlink

Joel de W4JNM
 
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