picklebill Posted June 8, 2007 Share Posted June 8, 2007 Just got a new dual band radio (2 meter/70 cm) and needed to mount an antenna on my Sunrader motorhome. The coach body is fiberglass, so there is no ground plane for the antenna to work against. My rule is not to drill any holes in the exterior fiberglass because of the possibility of water leaks. So I thought I would try to come up with an antenna that would mount on the front bumper. I took a fold-over Hustler antenna mast, cut off about 14" and mounted a steel plate on the end and attached a mag mount Diamond dual band antenna to it. Added 6 radials that point straight down, and to my great surprise, it works great. 50 watts forward and 1 watt reflected on 2 meters and about the same on 70cm. I got my inspiration from Greg KI6BJI and his mount which he mounted on his Sunrader roof. I have attached so pix. Bill WA7FBU Quote Link to comment Share on other sites More sharing options...
Gulfstream Greg Posted June 10, 2007 Share Posted June 10, 2007 Bill, that looks good. How did you mount it on the bumper? I see the top and bottom bracket but can not see how its bolted on. What brand and model is the antenna. I originally picked an Antennex with a spring coil on the whip but could not get a very good swr match. A Diamond super gainer 7500 matched up well but the draw back is no spring and its really high. Top of antenna is 12 ft 6 inches to ground. But as a note I did fabricate a spring. The antenna hits every tree on our road. Anyhow I am curios of the antenna brand and model. Greg Quote Link to comment Share on other sites More sharing options...
picklebill Posted June 23, 2007 Author Share Posted June 23, 2007 Greg - The antenna is a Diamond NR770H and really works well. I will send you a better picture of my bumper mount where it connects to the bumper. It is dark now, so I will get a picture of it sometime soon and sent it to you. I have made some changes since I took the pictures I posted - I did away with the mag mount scheme and used a Motorola roof mount on a 3" square piece of aluminum. Since I had a BNC connector in the feedline located near the antenna, it occurred to me that it would be easy to steal. I will forward a pic if the new antenna base as well. The match is even better now - on 2 meters, I have 50 watts forward and the needle just barely moves for reflected power. The rig is a Yaesu 7800R and works great. I really like the way it is set up to access the Wx channels with one keypress. 73, Bill Quote Link to comment Share on other sites More sharing options...
picklebill Posted June 25, 2007 Author Share Posted June 25, 2007 Greg - here are the photos of my bumper mount - I used the original Hustler base insulator as I want to still be able to use my Hustler resonators for HF mobile operation (future). The link you see to ground the mast is to get a DC ground to the base of the Diamond antenna so that the feedline shield is grounded at both ends. I had an ignition interference problem and the grounding knocked it way down. As you can see, I used the bolt that holds the bumper to hold the mount as well. This requires a square hole which took some time with a file but meant I didn't have to drill another hole. The back of the mount is held to the top rear lip of the bumper with a piece of "U" shaped metal bolted to the mount strap. I hope this makes sense as it's a little hard to explain. Also, the top strap that goes between the mast and the grille is made of plastic to keep the mast insulated when used on HF. 73 Bill Quote Link to comment Share on other sites More sharing options...
Gulfstream Greg Posted July 2, 2007 Share Posted July 2, 2007 Bill - that looks good. My next antenna project on the RV will be some sorta of HF antenna. It will be mounted on the rear bumper. I just built a rear bumper mount to accomidate a 31 ft jackite pole for using a 2m 70cm dual band dipole. Here is a photo of the jackite inplace on our last trip. The middile arrow is actually the 40 meter dipole I had up. Quote Link to comment Share on other sites More sharing options...
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