Multi Band Antenna

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Stage 2
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Joined: Sat Mar 19, 2005 7:08 am
What radios do you own?: HT1000,MT1000, HT50,MAXTRAC

Multi Band Antenna

Post by Stage 2 »

Has anyone ever found a mobile antenna that would work across multiple bands referring to some ham and commercial? Specifically, if possible I would like to be able to have 1 antenna connected to a Converta-com and then be able to put portables with different bands in it. I would like to be able to use the following bands. GMRS and Ham UHF, Ham VHF, Ham 6 Meter.

I know that the Comet CA-2X4SR is rated for all of these except the 6 Meter Ham. I was wondering if someone who has one of these ever tested SWR for 6 Meters on it as that would do it. Are there any other antennas out there that would do this?

I also have a 10 Meter portable for the same Converta-com, but, I am not looking for miracles here.

I figured that if anywhere, someone on this site has already tried what I would like to do.

Thanks in advance to all replies.
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Satelite
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Re: Multi Band Antenna

Post by Satelite »

Hello:
yeah I ran into the same issue with dual band applications with a few customers.
But don't have an answer for all three bands.
How ever I did offer them this option and there satisfied.
Ebay auction 272506481525
Its a NMO mount 136 to 174 MHz with 2.5 db gain and a 400 to 470 MHz with 3.0 db gain combo.
Its available as a SO239 option if you need another mounting option.
Satelite
RadioSouth
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Re: Multi Band Antenna

Post by RadioSouth »

The claims on that antenna seem WAY too good to be true. To be saltshaker sized, wideband across 2 bands and claim to have gain also ? Coming from China raises suspicion as well. I Strongly suspect these claims are Not all the seller says and wouldn't try it on any radio you value without performing an SWR check first, can't see that it can be resonant on VHF at all. 20-30 MHz wide on UHF maybe but that would be about it if it's well made.

To the OP, there's many good 150/450 whips available but they tend to be more narrowbanded than a single band 1/4 wave so getting both 440 and GMRS out out of a dual band whip might be a bit of a stretch.
motorola_otaku
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Re: Multi Band Antenna

Post by motorola_otaku »

RadioSouth wrote:The claims on that antenna seem WAY too good to be true. To be saltshaker sized, wideband across 2 bands and claim to have gain also ? Coming from China raises suspicion as well.
Will confirm that they are garbage/counterfeit. A friend of mine bought one, we swept it with an analyzer and found that it wasn't resonant anywhere. Took it apart and it's just a copper coil inside a cheap ABS housing.

OP: which line of radios are you using that gives you UHF, VHF, and 52 MHz? Genesis?
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fineshot1
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Re: Multi Band Antenna

Post by fineshot1 »

A Comet SBB14 is probably as close as you will find but no or poor TX performance for commercial
fineshot1
NJ USA
Stage 2
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Re: Multi Band Antenna

Post by Stage 2 »

Thanks for the input. I will probably go with the CA-2X4SR because if I had to add another antenna, there are 6 meter and 10 meter dual band antennas that would cover everything else. Regardless of rating, like you point out Radiosouth, I won't try anything without verifying SWR.

Motorola_otaku, you guessed correctly about the Genesis radios. There are tons of them still out there and, they are decent reliable radios. Yes, it's a pain to do the capacitor swaps on the 6 Meter jobs to bring them into the correct range, but, it's worth it especially when the parts cost less than a dollar. One of my "C" series MT1000's looks like it was never used.

If I find success with 6 Meters on the CA-2X4SR from an SWR standpoint, I will gladly share the info here, but, I'm not expecting this.
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mike m
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Re: Multi Band Antenna

Post by mike m »

Ditto on staying away from multi-multi band antennas and also having Genesis radios for 29 to 440 MHz..

All the quad band antennas that I measured were at the best ~-10 db at 29 MHZ and ~-6 db at 50 MHz.

As a result For 10/6meters I still use the old reliable MOTO DIPLEX ANTENNA METHOD then a lumped diplexer for 2/440 and a larsen 2/440 dual bander but I only use mine for receive out of the ham bands so the band edge vswr is of no concern for me.

There aren't any really good solutions for efficient ham/commercial wide tx antennas without resorting to individual antennas and a antenna switch assortment.

Speaking of 6meters, how did your cap mod values go with your 6 meter MT1000 ham conversion?

It's been several years since I wrote the original conversion document and I still haven't received much feedback as to if the cap values that I list work across the entire 6 meter band.

Mike
toojaygee
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Re: Multi Band Antenna

Post by toojaygee »

I have a couple of the CA-2X4SR NMO base, one on the car, the other as a spare base antenna on a mag mount stuck on the steel roof above the office.

The roof mounted one measures sub 2:1 SWR 134.3 to 181.3 MHz and 410 to 480 MHz, but is hovering just under 2:1 most of the way from 460 to 480. It is sub 1.5:1 430 to 460 MHz.

Interestingly it is sub 2:1 in the 213 to 239 MHz range as well.

It is very definately not usable on 6m - > 15:1 down there .....

jeff
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Astro Spectra
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Re: Multi Band Antenna

Post by Astro Spectra »

Jeff, welcome to BL.
Stage 2
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Re: Multi Band Antenna

Post by Stage 2 »

Lots of great feedback and discussion on this one. Thanks to all for sharing a bunch of headache saving info on not only the model I asked about, but, other models as well.

Jeff, I like to send a special thanks to you for doing all of the SWR legwork on the CA-2X4SR. I know that depending on the ground plane, SWR can vary, but, I would expect your trials are a pretty good snapshot of the antenna's capabilities. I would also like to add my welcome along with Astro Spectra to Batlabs. Lots of good people and info here. I look at it as Sort of having Motorola's R & D department for every radio that they ever made at your fingertips available 24/7. Plus, you have guys like Mike below who figure out how to make them do what even Motorola never intended to. Really cool!

Mike, it's been a while since I chatted with you on the Lowband MT1000. I will go over this shortly, but, to play by the rules and keep the moderators happy I am going to do so in the original post titled "MT1000 Low Band" so were not off topic like we would be here. See you and all others who care to check it out there.

Shaun
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tsunami_australia
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Re: Multi Band Antenna

Post by tsunami_australia »

I'd be curious to know how the 10/6/2/70 quad band antennas do. I'd assume there would have to be a massive compromise somewhere. I have a nagoya 770 or something like that now on the car that in testing matched a UHF and VHF ground independent RFI antenna(s). Even on aviation rx it has been brilliant and on our UHFCB rx. I've got another of their dual banders here and I wouldn't recommend it to anyone.
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