Anyone have a Diamond V2000A and a NanoVNA?

[sallen07]

OK two disclaimers before I state my question:

1) Yes, my question is about GMRS, but the antenna in question is a 6m/2m/70cm amateur radio antenna, hence my choice of forum.
2) Yes, I *know* this isn't a GMRS antenna. That's not the question, but thank you anyways.
3) Yes, I know that SWRs can vary depending on the installation, or even between two antennas that are "the same".

If anyone has that antenna and a NanoVNA (or other SWR meter), could you please sweep the antenna in the GMRS range (462.x and 467.x) and give me a ballpark SWR reading? I don't need exact figures (although I will certainly take them), but I'm curious if they are < 2:1 (or close) or more like 4 or 5:1.

I am looking at swapping around a couple antennas, and my current plan is to take the Diamond X50NA that I'm using for 2m/70cm and replace it with a Comet CX-333 so I get 1.25m too. (I'm also hoping for better performance on 2m/70cm.) I would then take the X50 and use it for GMRS. (Again, I *know* it's not a GMRS antenna, but for the limited amount of transmitting I do on GMRS it's close enough.)

It occurred to me that I could instead install a Diamond V2000A and pick up 6m (the reviews suggest it works well on the FM portion, which is what I'm interested in anyways), but I'm wondering if it would work "well enough" on GMRS to use it for that too. If it won't, then I'll probably stick with my current plan for the X50 and continue to use a 6m ham stick stuck on top of my truck when I want to work 6 meters.

Thanks in advance!

 

[KK2DOG]

I had the exact same question a couple of days ago, so I conducted an experiment at the DOG house. The UHF specs of the Diamond V-2000A are 440-450MHz which is lower in frequency than GMRS is. Anyhoo, I programmed my radio for GMRS channel 1 (462.5625) which ran through a Daiwa CN-801HP meter into my Diamond V-2000A which is mounted on the roof. Regardless of power level, the SWR was so high that it was off the scale. So to answer our question...nope, aint gonna work. I was so hoping it would too.

 

[VK3RX]

I ran a test of my V2000A using a RigExpert AA600 analyzer which goes to 600MHz and got the plots below.

I wondered about the first indicating VSWR pretty flat across the range, so ran the second 400-500MHz. I also checked the VSWR with other gear on 430-440MHz and 477MHz and its consistent with the plots.

I don't know what the internal construction is but I can key up distant repeaters on 70cm so my V2000A is still working

The Daiwa CN-801HP specs say its upper limit 200MHz which might explain the different reading on 462MHz.

Maybe wait for another check from someone

 

[sallen07]

Thank you!

Looks like < 2.0 all across the GMRS band, which would be just fine.

 

[VK3RX]

You really need to buy or borrow a VSWR meter covering the 462MHz range to check your own installation

 

[KK2DOG]

VK3RX...yep, I totally overlooked that.

 

[PE1JOD]

I ran a test of my V2000A using a RigExpert AA600 analyzer which goes to 600MHz and got the plots below.

I wondered about the first indicating VSWR pretty flat across the range, so ran the second 400-500MHz. I also checked the VSWR with other gear on 430-440MHz and 477MHz and its consistent with the plots.

I don't know what the internal construction is but I can key up distant repeaters on 70cm so my V2000A is still working

The Daiwa CN-801HP specs say its upper limit 200MHz which might explain the different reading on 462MHz.

Maybe wait for another check from someone

View attachment 122464View attachment 122465

Nice result I wonder how the rest of the bands show, VSWR-wise. I do have a nanoVNA, with a.o. setups in memory to scan segments of 100 MHz, just to see how an antenna works out in a broader spectrum - I've already seen some surprising results.
Could you do a scan of a much broader spectrum and post the screenshots, to see which frequencies are within an acceptable VSWR?
Currently considering a new antenna and the V2000A has at least a good operating mode on 400-500. But how does it perform on the other bands?
I was looking at a Diamond D130 or D3000 discone, because of it's broadband characteristic - but it has no gain on 6/2/70 :-(
And then I saw the V2000A - and your measurement. And I got curious

 

[VK3RX]

Sorry I can't do any further tests at the moment as that antenna is down due to house external reno about to happen here.

However I recall that as expected the VSWR dips to low on 2m & 6m, quite a dip on the latter depending on whether it is adjusted for the low or high end of 6m. I also recall that the VSWR was high either side of 6m.

 

[Ubbe]

I ran a test of my V2000A using a RigExpert AA600 analyzer which goes to 600MHz and got the plots below.

It looks a bit suspicious in the 400-500MHz plot. A HAM KD8CGH did a 420-450MHz sweep and looks much more what you would expect. His V2000A seems to be tuned to 426MHz but at 450MHz it's still only 2:1 VSWR which normally are considered to be the bandwidth limit. If you have a lossy coax it will work more like a dummy load, showing good SWR readings but less power are reaching the antenna.

If the antenna are tuned to 426MHz it would probably be 3:1 or higher at 467MHz that equals 25% of power loss, so perhaps no big deal, but the radiation pattern might change to lose much more power at the horizon elevation level. It's an 8dBi antenna with a fairly flat pancake radiation pattern that you do not want to lift from the horizon up in the sky.

/Ubbe

 

[VK3RX]

Cable is 30 feet of new earlier this year LMR400.

Difficult to read the numbers on that chart - is the VSWR on the left hand side? If so, the fact that the trace varies between 1:1 to 1.5 across the range 420-450MHz isn't wildly inconsistent with my chart.

And as I said, I also verified the results on 70cm & 477MHz with other gear.

As to why the antenna is fairly broadband across the 400-500MHz range, I don't know the internal design.

Perhaps there is a 50 Ohm resister in there ......

 

[Ubbe]

Perhaps there is a 50 Ohm resister in there ......

Yes, it almost looks as if the coax are terminated with a resistor over the antennas loading coil, or the antenna element are coupled very lightly to the coil and not having much impact on the readings.

Your chart max out at 1,5:1 50MHz from the tuned center, which seems to be 445MHz. KD8CGH's chart only covers 420-450MHz and it is 1:1 at the bottom and the line above it are 2:1 and almost reach that already at the 450MHz point, 25MHz from the tuned center that strangely seems to be 426MHz and not 445MHz but the chart looks more like a real antenna.

Maybe one, or both, of the antennas are a Chinese copy of a V2000A?

/Ubbe