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Comet B-10 nmo swr

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#1
I need a low profile antenna for my vehicle SWR on UHF is practically nothing but on VHF it is only 1.0 from 145 to 146 exactly if you go to 146. 01 the swr jumps 2 about halfway to 1.3 I mostly used to meters is there any way to adjust the antenna have better SWR on that side

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#3
No you're reading you correctly UHF barely moves the meter at 35 Watts most of the band but two meters side is not perfect

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#4
This is exactly what it is at 50 Watts with magnet mount b - 10 nmo dual band antenna
144.5= 3
145.0= 1.2
145.5= 1
146.5=1.2
147.0= 1.3
147.6= 1.8
so it's basically good below 1:47 correct?


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#5
You are good everyone on 2 meters. Except below 144.5, but I'd suspect that as a faulty reading. Jumping from 1.2:1 to 3:1 in 500KHz is unlikely.

And, for an electrically short compromise antenna on a mag mount, I'd agree, it looks pretty good.
 
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#6
And if you are concerned about stressing your radio, don't run it at the full 50 watts. Throttle it back and it'll be happier.
 
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#7
Okay I'm just using a radio that works good but it is kind of old and do not want to stress it out. it in the house it's 1 pretty much the whole bandb I wanted to do the swap because the faceplate on the one I have in the house right now looks really good in my truck but I'm debating what to get for the house I want something with more receive range people are telling me the icom ic 2730a anyone have an opinion on this?

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#9
I need a low profile antenna for my vehicle. SWR on UHF is practically nothing, but on VHF it is only 1.0, from 145 to 146 exactly. If you go to 146.01 the SWR jumps 2 about halfway to 1.3. I mostly used to meters is there any way to adjust the antenna have better SWR on that side.
You do not have a problem. Any further adjustment would be a waste of time. And, there is no guarantee that you will make it better. You might make it worse.

If your SWR was perfect (1:1) over the entire band, then you would have a problem. Your SWR readings are well within range. A 1:1 SWR over the entire range is called a dummy load.

All of the power from your transceiver, minus some coax losses, will be radiated. A high SWR will add to this loss, but far less than you might think. For example, if you were using 50 feet of RG-8x between your rig and the antenna, at 146 MHz your loss would be about 2 dB. If the SWR was 2:1 it would only contribute and extra 0.3 dB of loss.

Better coax, or shorter lengths, would reduce these losses. But this might also make your SWR look higher than what you are already seeing.

Martin - K7MEM
 
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#11
Purchased a slim nmo mount in place of the large one I had and SWR is worse? Anyone's thoughts?

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k7ng

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#12
Mag mount antenna bases are just not going to give you what you want in terms of antenna performance, whether it's low VSWR (not as important as some folks make it sound) or how well the antenna 'gets out'. I don't know what 'slim mount you're talking about, but probably it has a smaller footprint? Then it's going to make everything worse.

A mag mount allows you to put the antenna in a favorable spot on your vehicle, but the performance you get may offset that - a lot. Sorry, I've used magmounts, and in some situations I still do, but if you can, and are willing to drill, or punch, a hole, try a permanent mount.

Let any VSWR below about 1.8:1, which is where a lot of radios start to fold back their power to protect themselves, just go. Especially dual band / multiband antennas, they are generally not intended to be tuned.

Just MHO, but keep it in mind.
 
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#13
My trucks at lease I'm planning on buying it out but I'm not 100% sure so I don't know if unless I could cover the whole up so they didn't realize it was there

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#14
The slim magnet mount has a lot less strength and the footprint is small

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#15


This Larsen works it works well just going to stick with that

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#16
My trucks at lease I'm planning on buying it out but I'm not 100% sure so I don't know if unless I could cover the whole up so they didn't realize it was there.

Most lease people don't care about antenna mounts through the roof. All they care about is that it is water tight. But to make you feel better, go back to the dealership and talk to the lease manager and get the answer straight from the horses mouth. Then get him to put it in writing.
 
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#17
Most lease people don't care about antenna mounts through the roof. All they care about is that it is water tight. But to make you feel better, go back to the dealership and talk to the lease manager and get the answer straight from the horses mouth. Then get him to put it in writing.
Good idea thank you going to ask

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#19
They now make a steel plate that goes in between the 3rd light to mount magnetic strobe lights on would work well for an nmo mount no holes with hole type performance
 
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#20
They now make a steel plate that goes in between the 3rd light to mount magnetic strobe lights on would work well for an nmo mount no holes with hole type performance
But you still need adequate ground plane, That is 19" in all directions for 2 meters. Visualize a 38 " dia piza pan.

Remember, the groundplane IS the other half of the antenna.

The mag mount is post 15 photo has a very good coupling to the roof, giving a better "connection' to the groundplane. A small diameter mag mount does not couple well at lower frequencies.
 
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