mmckenna
I ♥ Ø
I could not help myself in "bumping" this picture. "Wireless Mag mounts". The new doctrine.
"Whacker central calling Unit 15".
Oh, never mind, Unit 15 won't hear the call….
I could not help myself in "bumping" this picture. "Wireless Mag mounts". The new doctrine.
I could not help myself in "bumping" this picture. "Wireless Mag mounts". The new doctrine.
But where did all the coax go?
Okay, McKenna, this one's for you!
102 inches of stainless steel - the standard by which all mobile CB antennas are measured. This true quarter-wave gem has earned the reputation as the perfect pairing for your mobile CB.
The problem with it is that it isn't practical for most of us. If you own a crapper old pickup truck or big boat of a car, a 102-inch whip on the bumper might be ideal. But for a modern personal or family vehicle, it looks like redneck dog poo.
My wife would file divorce papers if I drilled holes in her beloved Pilot and added this giant monstrosity to it. That being said, what kind of suck ass placement is a bumper mount or side mount anyhow?
It is a commonly-held belief that the 102 whip is such a good performer that it generally overcomes a poor mounting position, but to what degree?
How well would this beast work if you could roof mount it?
With kick butt magnet mounts like the Stryker, the Wilsons and other Tram antennas mounted perfectly at the center of the roof and carrying a good SWR, will a crappily mounted 102 still outperform it?
Opinions?
I think all those Larsen measurements showing losses for various placements on a vehicle were made at 800 MHz for the old AMPS cellular standard (bag phones with external antenna jacks, if you remember those) and 800 MHz public safety trunking systems. Not sure those measurements apply to most CB, ham radio, and modern cellular systems as the frequencies are very different from 800 MHz by a factor of 2 or more. Or to say it another way, capacitive coupling measured at 800 MHz is going to be very different from capacitve coupling measured at 27.185 MHz. Here's a screen shot of the caption that goes along with that figure from the Larsen literature:Correct. When comparing like for like antennas, mounted in the center of the roof of a vehicle, there is a 0.2dB loss for the magnetic mount. It's highly unlikely anyone is going to hear that 0.2dB difference.
All things being equal, mounting the same antenna on a mag mount versus a permanent mount isn't going to amount to much.
However, there's other things you need to consider.
There is a difference between a capacitively coupled ground plane and a real ground plane. That's where the 0.2dB comes in.
So what are your thoughts on the bumper-mounted HF whips on military vehicles where they attach to a guy rope on the front bumper?
Id say by this point in the thread you’ve understood that wringing every last meter of reception radius isn’t quite going to be overcome by a quarter-wave, and that’s before accounting for other conditions detrimental to the objective.
A roof-center mount with short (town) and long (country) antenna options ought to keep the wife happy. Base load. That approach sure looks hard to beat
I’ll get my truck install done this year. It’s meant to be able to run an almost 15’ tall quarter-wave on the roof (just unlikely to get used much as one needs to be on major highways W of the 98th Parallel). Remind me (I’ll have some kind of thread) and if you want me to try your antenna we’ll figure something out.
Why such a tall antenna desired? A travel trailer behind me that needs about eleven feet of clearance. Getting above that matters. If it doesn’t work as well as I hope it might, I know I’ll have done what I can in that regard.
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As soon as I get my steel tire carrier/bumper for my Jeep, I am installing a 102 inch stainless steel whip. It is virtue-signalling to show my political support for VHF-low band. Save the long sine wave!
I would buy one in an instant if it had an aluminum roof option.I'll reply to my own post here with a picture of my new truck. Been looking it over for antennas and that will be different than what I thought I could do. For now I'm looking at two NMO trunk lip mounts on the rear of the hood either side of the hinges. Then my military mount with interchangeable plates for NMO, 3/8-24 and a Hi-Q antenna quick disconnect will go on the drivers side upper bed wall about 2/3 back from the cab. I wanted that mount to go on the front bed wall up high but the Tonneau cover will interfere with that when rolled up.
Hmm, something about this new truck reminds me of the old Hummer. Maybe that's why I got it. Duhhhh.
View attachment 102921
I would buy one in an instant if it had an aluminum roof option.
Yep. Here we go again.I could not help myself in "bumping" this picture. "Wireless Mag mounts". The new doctrine.
Yep. Here we go again.
Just can't help it.
Shame to the unwashed nonbelievers!
Drill the hole in your roof or be damned!
Anybody who don't drill a hole in the middle of their $50K car roof is a stupid, embarrassing heathen who is giving away 0.1dB, or is it 0.2 dB, or maybe 0.5dB...we don't know cause we can't tell the difference through the speakers, but they're stupid anyway.
I think all those Larsen measurements showing losses for various placements on a vehicle were made at 800 MHz for the old AMPS cellular standard (bag phones with external antenna jacks, if you remember those) and 800 MHz public safety trunking systems. Not sure those measurements apply to most CB, ham radio, and modern cellular systems as the frequencies are very different from 800 MHz by a factor of 2 or more. Or to say it another way, capacitive coupling measured at 800 MHz is going to be very different from capacitve coupling measured at 27.185 MHz. Here's a screen shot of the caption that goes along with that figure from the Larsen literature:
View attachment 102920
They may be available through Motorola dealers but they were expensive, close to $200 I think. I found two on Ebay for reasonable prices, I forget the exact price but under $50. The part # on the box is TRN4505A and its for the Mobat/Micom HF SSB series radios.
I'd love to find a couple of these. Been watching ebay for some time and none. NLA from Motorola which sucks.
I looked also. Am well-enough pleased with BREEDLOVE that unless I stumble over a nice MOTOROLA piece to let the search end.
That said, finding a quality spring is a problem. The Hustler 30-series is okay ($30),but the next step appears to be CAL-AV at $100.
rfjunk sells risers of various lengths. Elsewhere have come across those who trimmed the bottom of the whip to keep the assembly to 108”.
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