CB Radio antennae and mounts. - Page 3

dbhosttexas · 12-08-2023, 04:09 PM

Quote:

Originally Posted by Orv

Good point about the SWR. I'm not sure how the metal framework of the top would affect it, being in the near field of the antenna and all. I had similar thoughts about my 2m band antenna, and I ended up going with a 1/2 wave so I could mount it on the pop-up top itself. (1/2 wave doesn't require grounding.) That'd be less practical with a CB antenna because they're so much heavier.

I have seen NMO CB whips but they tend to be on the short side and I imagine aren't very efficient.

Because of the fiberglass roof I really don't have anywhere good to mount the antenna. I am going with a 5/8 wave Firestik mostly becaue of prior experience with Firestik antennas although my prior was on a Jeep. Again nowhere really good to mount an antenna. Kind of used to be being directional... I have SOME concern about mounting in the hood channel, mostly as the hood itself is composite and not metal at all.. Other options would have been like a rear bumper mount for a 102 with a standard 6" spring which is a what, 1/4 wave I think...

Not much roof to mount to, and clearance issues if I do mount to the roof, unfortunately I checked, the front window screen does NOT unzip to allow access to the front of the roof, that would mean stretching to reach an antenna mounted up there to remove it every time I want to put it on / off, sounds like a pain in the butt...

I hate to say it, but I think my best option at least that I can think of, is that fender channel mount... Which I am less than ultra thrilled about.

Orv · 12-08-2023, 04:32 PM

I suspect the fender channel mount will be fine. It sounds like you're going to be using it over pretty short distances, so wringing out every bit of efficiency isn't going to matter too much. I think your main concern with a fender channel mount will be electrical interference.

102" whip is a quarter wave, yeah. That's probably your most efficient option, although with a van you might get SWR changes as it sways. I had thought about using a trimmed 102" whip for 10 meter mobile, at one point, but never got around to it.

dbhosttexas · 12-08-2023, 04:46 PM

Quote:

Originally Posted by Orv

I suspect the fender channel mount will be fine. It sounds like you're going to be using it over pretty short distances, so wringing out every bit of efficiency isn't going to matter too much. I think your main concern with a fender channel mount will be electrical interference.

102" whip is a quarter wave, yeah. That's probably your most efficient option, although with a van you might get SWR changes as it sways. I had thought about using a trimmed 102" whip for 10 meter mobile, at one point, but never got around to it.

I've never had an issue with SWR drift with a 102, but it was installed on the front of a truck bed.... I bet with varying proximity to vast amounts of sheet metal I.E. bumper mounting on a van, WOULD impact SWR and likely more than just a tiny bit...

Honestly a Sportsmobile with a Penthouse roof that gets parked in urban parking structures frequently is NOT an ideal platform for a super efficient antenna installation. Old school trucker mirrors would have provided a better platform for antenna mounts but provided a LOUSY ground plane...

Seems like I kind of can't win in this scenario, so I will settle for do the best I can manage...

Orv · 12-08-2023, 05:05 PM

For four-wheeling it doesn't have to be a perfect isotropic radiator, it just has to get over the next hill.

dbhosttexas · 12-09-2023, 11:32 AM

So the mount is here, although Coax has yet to show up... I have it mounted on the middle bolt in the fender, I can mount further forward getting it away from the windshield, or closer to the windshield giving it a greater bit what there is of it, ground plane. Considering the latter. The Coax is on the truck being pushed from Portland here and should be here Monday...

dbhosttexas · 12-11-2023, 02:34 PM

So the Firestik is about to be sent back to Amazon. This thing, the coax they sent me, or the mount just sucks. Super high SWR no matter what I do.

Dug the Radio Shack mag mount out of the recycle bin, whacked at the stinger length until SWR came into line. I can plop it center of the exposed steel roof, and 1.0 on all channels 1 -1 40. Nobody out there in range for a radio check though... Bleh. Probably just run the coax out the passengers side door since I am a solo camper no passenger and have a whack at it when I hit the road...

Now I need to package this stuff back up for Amazon and get it out of my hair.

dbhosttexas · 12-12-2023, 10:12 PM

Update. Too dark to take pics, but I moved the mount forward to the furthest forward fender bolt, added a ground strap from the mount to chassis ground, and changed coax cable to a Firestik FireRing cable to get better clearance to the mount VS the ring terminal connectors that aren't super cleanly installed on the other coax...

I got the SWR down to 1.1 accross the band, until I put the cap back on the tunable tip, then it went to heck. Pulled the tip and looked down the shaft, looks like wires broken in there from the factory, sending it back. Going to try another one, just disappointed this one made it out past QC...

Temporarily using the Realistic mag mount. NOT happy about that, but it is what it is...

dbhosttexas · 12-22-2023, 08:45 AM

Final update:

The replacement Firestik II antenna came in, the bad one went back to Amazon. I could NOT get the SWR below 1.5 on 1 and 40, I could get it to 1.2 on 20, so the arc is actually inverse from what I would expect. Giving up on Firestik.

Dug around in my shed and dug up the big dog.
102" Realistic stainless steel whip antenna, ProComm 6" stainless steel barrel spring, ProComm giant mount upper to match the Firestik lower.

All of the sudden SWR is 1.0, well honestly a wiggling shave above but just hovering above 1.0 on all channels. I cannot get it better at all, God help the parking garages...