The XYL and I recently bought an RV, and I was wondering if there was a way to mount an HF wire antenna lengthwise above the roof. The roof of the RV is about 12 feet high, so I figure I could have about 2 feet clearance from the fiberglass roof. Thanks for any input (even from other viewers) KE8NFK
I realized I do not know the story of your rambling lifestyle. How many days a year do you spend on the road?
Great vid. Improvised is the way to go so don't be shy about them being rough. I use a Breedlove so-239 ball mount on the van. it holds the diamond screwdriver while mobile a doubles as a coax connection for any improvised antennas raised. Any balun required hangs off that. I do like the idea of a carlin box as a junction though. Going to keep that in mind. Luckily here in the northeast I usually have trees to hang antennas from but the mast is a great addition I should consider.
I run an inverted-L configuration (horizontal portion over the RV) but keep it much higher than two feet. For clarity, I only do this when parked. I sometimes have problems with RF getting into various things inside the RV so I do reduce the power to mitigate it. If I'm able to run the antenna in a different direction not over the RV, RFI is not a problem.
Everyone's mileage will vary, but I suspect you'd have three problems with that approach. First, length. A 20 meter dipole might be doable, but lower freqs would be a problem. Second, noise. Solar charge controllers, appliances, the RV's own power converter, and especially inverters are huge noise sources on HF. Finally, RF. You'd be directly in the RF field of the antenna when transmitting, which could cause all kinds of interference with stuff in your RV and probably cause RF noise on your transmitted audio as well. You really want your antenna away from the vehicle if possible. My little vertical on the back of the RV is always noisier than the other antennas, but not too bad. It's not parallel to the vehicle though, so that helps. And I usually run low power, 5-30 watts, so it doesn't cause much of a problem when transmitting. I do sometimes here it on my audio system.
I have an old Alpine Screwdriver attached to the ladder on the rear of my Motor Home. For "quick" on the air, I climb the ladder, install a 72 inch whip and then tune by noise level to about where I want to be, then let the IT-100 handle the rest. If I am going to be stationary for an extended period of time, and have about 70 feet of space, I put up an EFHW. I have a 2x2 plywood base that I put a short stub of pipe on. Slid a section of top rail or military surplus tent pole over it and attach the antenna to the top. I cut the top rail into five foot sections and of course the tent poles are about four foot each. I have my tuner (IT-100) mounted in an outside compartment. Connect the coax to the antenna and to the tuner and I can work all 20m, 40m and parts of 80m depending on the height. I do guy the two uprights to keep the antenna wire from drooping. Could use the ladder for one anchor point, but have not done that yet. Since I only work HF when stationary this works well. For 2m/70cm I have a short Pulse (Larsen) dual band antenna mounted on a metal plate in the middle of the roof.
The world is so wacky nowadays that being nomadic is a viable option. RV's are seeing record sales....so also on second --non urban--homes (family here just got a mountain house in NH).
I was responding to the 'story', not the question. There is an increase this year in RV usage, which makes this video , perhaps, of greater import than in many years past. 73 Chip W1YW
I don't suppose you've swept those antennas with an analyzer? Almost anything will work under the right conditions. I recall working Dx on ten meters with an eight foot string of paper clips and a Dx-20.
