I just recently installed an aluminum roll bar in the bed of my truck. There are two 6 inch round metal lamps that sit atop the roll bar. In between the lamps sits a 102 whip on a Radioshack 21-1118 barrel spring. This all sits in a gumdrop mount.
The antenna, spring and gumdrop are all brand new.
I am running an 18 ft. piece of RG8X coax into the radio. I know this coax is good, it works great with my base set up.
Pictures of my install are below. The antenna sits above the roof and bed of the truck. The roll bar is bolted to the bed, and the lamps work if only the red wire is attached to a 12VDC source.
I have tried running a ground wire from the round knurled area of the PL259 to a good ground.
I have tried different a different whip. I have tried adjusting both whips. I have removed springs. I have added both springs plus an extension.
I have done my SWR testing with the doors closed, me inside the vehicle and I even had the vehicle in an open area away from trees, poles and buildings.
I even tried placing cloths over both of the lamps thinking maybe they were reflecting some of the signal causing a higher than usual SWR reading.
However no matter what I do, in any of what I have mentioned above, I cannot get the SWR below 2.0:1. And that's across all 40 channels.
So in other words right now with the brand new 102 whip, brand new 21-1118 spring and brand new gum drop mount, I am sitting at a 2.0:1 SWR on channel 1, 20 and 40.
The only other thing I can think of is the roll bar is only maybe 8 feet wide by 4 feet long.....if it's possible that the antenna is using just that little bit of area to reflect the waves off of....which I would have thought the antenna, while sitting maybe 3 inches higher than the roof of the truck, would be using the roof, hood and bed as the ground plane.(my last truck, same make and model, I had this same antenna and spring mounted in bed on bulkhead, SWR was always 1.2-1.4:1)
Any thoughts on this? I really want to get my SWR to 1.5:1 if not lower than that.
Thanks in advance.
The antenna, spring and gumdrop are all brand new.
I am running an 18 ft. piece of RG8X coax into the radio. I know this coax is good, it works great with my base set up.
Pictures of my install are below. The antenna sits above the roof and bed of the truck. The roll bar is bolted to the bed, and the lamps work if only the red wire is attached to a 12VDC source.
I have tried running a ground wire from the round knurled area of the PL259 to a good ground.
I have tried different a different whip. I have tried adjusting both whips. I have removed springs. I have added both springs plus an extension.
I have done my SWR testing with the doors closed, me inside the vehicle and I even had the vehicle in an open area away from trees, poles and buildings.
I even tried placing cloths over both of the lamps thinking maybe they were reflecting some of the signal causing a higher than usual SWR reading.
However no matter what I do, in any of what I have mentioned above, I cannot get the SWR below 2.0:1. And that's across all 40 channels.
So in other words right now with the brand new 102 whip, brand new 21-1118 spring and brand new gum drop mount, I am sitting at a 2.0:1 SWR on channel 1, 20 and 40.
The only other thing I can think of is the roll bar is only maybe 8 feet wide by 4 feet long.....if it's possible that the antenna is using just that little bit of area to reflect the waves off of....which I would have thought the antenna, while sitting maybe 3 inches higher than the roof of the truck, would be using the roof, hood and bed as the ground plane.(my last truck, same make and model, I had this same antenna and spring mounted in bed on bulkhead, SWR was always 1.2-1.4:1)
Any thoughts on this? I really want to get my SWR to 1.5:1 if not lower than that.
Thanks in advance.