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Mobile 3-foot mobile antennas
- Thread starter DeedleD
- Start date
Deedle,
Tune your antenna with the linear off. Or out of system. The higher the power the higher the VSWR.
Just the radio and antenna. Get it as low as possible. Then operate. I rarely, if ever use the high setting. Usually low or med. 26 years of running radio with amp and never a problem.
Remember most Low Drive Amps no more than 4w input. Preferably 1w. I blew my 148 driving 6~7w into the Palomar LD 450.
Good counter poise, or GP is crucial. Good connections through out system, and grounding. Bonding will be worth the effort.
Tune your antenna with the linear off. Or out of system. The higher the power the higher the VSWR.
Just the radio and antenna. Get it as low as possible. Then operate. I rarely, if ever use the high setting. Usually low or med. 26 years of running radio with amp and never a problem.
Remember most Low Drive Amps no more than 4w input. Preferably 1w. I blew my 148 driving 6~7w into the Palomar LD 450.
Good counter poise, or GP is crucial. Good connections through out system, and grounding. Bonding will be worth the effort.
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Roger that! Thanks for the pointers. Like you pointed out it's no use running at max power since, in my experience, after about 150W there is little difference so max is always on level 2 when the linear is on, and I set it back down to that after making sure SWR was as low as possible at the highest setting. When it gets nicer out I'll be drilling the roof and make sure it's bonded for best performance. My truck has a roof rack so I might make something custom for the antenna on top of there instead of drilling the roof, as an alternative. Also this amp is high drive so I can put about 35W into it to get 300+ out, from 3.5W (stinger off) I get about 75W out on max setting. The 980 SSB stinger takes 3.5W to 35W average. I don't run the linear in normal operation, just when testing.
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It's a 3rd gen Toyota 4Runner, so I guess it's not really a truck...SUV is probably more accurate.
If you decide to drill consider placing a backing plate bottom side of roof. Flex will mess up a roof. 3-4 inches dia. or larger if possible. 1/8" thk. Run a ground wire from plate to frame you can tether bonding wires from this to panels. You gotta pull the head liner any way. Might as well do it right.
Pretty sure attaching a mag drill just might be a weeeeeeeee bit over kill for sheet metal and 1/8" thk. metal. I read some of that site. Had some good pointers. You have to improvise a lot of things and try others.
Oh yea, definitely! I was thinking if I'm gonna drill it would probably be right between the two roof braces as can be seen below, the middle one with text and the one behind it since they're closer together but then the antenna would be more towards the back of the vehicle as opposed to the middle, so maybe I can just use the middle brace and connect the backing plate to that one.
The roof braces connect to the frame of the vehicle so everything would be grounded in this fashion... Guy that took the below pic was posting on forums showing how he reinforced the roof of vehicle which is same as mine, so it really helps seeing what's under the head liner!
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I would suggest located near the one marked roof bracing, not through the bracing, just forward of it w/ a backing plate of sorts. I have seen dump trucks fitted with NMO center of roof and no backing plate. After a while flexing of the sheet metal fatigued resulting in stress cracks. Possibly use whatever you decide and slip it between the bracing and roof, or just an edge of the plate lapping along the edge of the forward side of the bracing.
Another concept would to be fabricate a bar with legs and appropriate feet for surface mount along the parallel roof bracing along each side. This would be on top of vehicle and at same top elevation of roof rack. Screws into the parallel roof bracings. Would add another rack support and would section your roof rack some by providing tie downs.
If there is a really cool looking tough metal add on roof rack system, like those seen in safari vehicles for packing elephant tusks and rhino horns, you could convince the wife of added expense for those shopping safari's into the deep bowls of city shopping centers and strip malls. But then you would have to get a high lift kit and rock crawler tires and KC lights. Not to mention the two Jerry can brackets and cans for added capacity of fuel for those long shopping safari's outside of normal operation.
Another concept would to be fabricate a bar with legs and appropriate feet for surface mount along the parallel roof bracing along each side. This would be on top of vehicle and at same top elevation of roof rack. Screws into the parallel roof bracings. Would add another rack support and would section your roof rack some by providing tie downs.
If there is a really cool looking tough metal add on roof rack system, like those seen in safari vehicles for packing elephant tusks and rhino horns, you could convince the wife of added expense for those shopping safari's into the deep bowls of city shopping centers and strip malls. But then you would have to get a high lift kit and rock crawler tires and KC lights. Not to mention the two Jerry can brackets and cans for added capacity of fuel for those long shopping safari's outside of normal operation.
Like I tell all new Members I learn a lot from this forum & still learning ! Thanks to Slowmover , I learned of K0BG2's site , never visited it before ! Some awesome reading on it for sure especially on " bonding " ! Thanks for the heads up ! 
You are thinking rotabroach, not rotacut. The rotacut is a fancy hole saw that can be used in a hand drill.
Drill the hole and be done with it. I promise you wont regret it..