Antenna measurement device

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  • Updated 3 years ago
Antenna measurement device needed. Could you reccomend an antenna measurement device. I have a watt meter in my shack and its showing a large swr and about 20 watts output power rather than 100. The flex 6700 autotuner is reporting succesful but im still wondering if i have an antenna problem causing the repeater problems i've posted.'thanks
Jim
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James Madden

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Posted 3 years ago

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Jim Gilliam

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You want an antenna analyzer. There are many available at varying costs depending on the type of display and measurements. MFJ makes a variety of analyzers you might check out.
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James Madden

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Thanks ill check. I dont want something in the ham shack im thinking a portable device that i can take outside.
Jim
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Alex - DH2ID, Elmer

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James, I use this one http://www.eham.net/reviews/detail/9678 and find it great for HF.
There are other models for VHF/UHF, but they are more expensive.
For SHF and up to 6GHz I use a spectrum analyzer.
73, Alex - DH2ID
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James Madden

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Thanks Alex. I think this is exactly what i want. I dont see ant recommendation for a portable antenna to attach for measuring antenna field strength. Do you have any reccomendations.
Jim
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Tim - W4TME, Customer Experience Manager

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Remember, that you want to analyze the entire antenna "system" which includes the antenna and the coax connected to it.
(Edited)
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Kevin Va3KGS

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Hi James

I use both the LP-100A from Telepost Inc., and RigExpert AA-600.

The LP-100A stays connected to the station for continuous HF Power and SWR readings. (not VHF/UHF).

The RigExpert is my portable unit,  and covers up to 600Mhz. 

Check these out. 

Good luck

Kevin, Va3kgs

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Duane, AC5AA

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Whatever you use, if you place it between the output of your rig (following the ATU) and the antenna system, and there is a mismatch that the ATU has tuned out, you are NOT going to see that as a match on your external meter, because it is most likely built for a 50 Ohm nominal impedance. Similarly, your power measurements, both forward and reflected, will not be accurate either. So, be sure you are using the meter correctly! Hope this is helpful.
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James Madden

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Thanks for this very useful information. That explains why i'm seeing such low power witha wattmeter. What is the best practice to get correct measurements?
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David Decoons wo2x, Elmer

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To get a correct measurement on the external wattmeter you will need to use an external antenna tuner and not the internal.

It would be connected

Radio -> Wattmeter -> External tuner -> antenna

Dave wo2x
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Greg - N8GD

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Why not try out the "SWRPlotter6K" program by K9DUR that essentially makes your 6700 a complete antenna analyzer?  You can save the plots for entire bands for future reference.  Here's the link:

http://k9dur.rnaconsultingservices.com/smartsdr_utilities.html

Scroll down the to the download link for "SWRPlotter6K" and click on it to download the program to your PC.  It works quite well!

Greg - N8GD
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ka7gzr

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Thanks Greg! I went to Rays site and got the "Plotter". What a slick program!

Jim

ka7gzrt

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James Madden

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I like this and downloaded the software. It unfortunately doesnt seem to work on my windows 10 64 bit computer. Jim
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Greg - N8GD

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It works FB on my Windows 10 64-bit i7 machine.  You need to have SSDR running with a single slice open.  Turn off the ATU.  When you start SWRPlotter6K, a window will appear displaying your radio and asking to connect.  Highlight the radio and click on "Connect" below.  You might want to reboot your PC before running it for the first time.  A local Ham friend rebooted his system after the program failed, and then it worked OK.  I just ran it on my system again to confirm it.  You do not need DAX or CAT running.  There is a PDF manual that installs with the program in the "C:\Program Files (x86)\RNA Software\SWRplotter6k" folder.

Greg - N8GD
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James Madden

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restarted my computer, turned off atu. a window appeared in swplotter but my radio didn't. sigh
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James Madden

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Ill try again. Imlaunched the plotter before my radio, perhaps thats the problem.
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Greg - N8GD

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Might be a firewall issue.  Are you running a firewall or security suite other than what's built-in to Windows 10?  The SWRPlotter6K passes info via TCP/IP so if the firewall blocks it, that may be the reason you don't see the radio.

Greg - N8GD
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Kevin Va3KGS

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Afternoon Greg

Just ran the SWRplotter6K and it worked great.  Plotted 6-80m on my Dipole antenna.  Had all the bands plotted within 5 minutes.  80m is the only band I can't operated on with such a high SWR.  I now know where to play in each band!!  Thanks for the suggestion.

Cheers

Kevin, Va3kgs 

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Mike - W8MM

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I absolutely LOVE my RigExpert AA-600.

I already had an AA-520, which worked well.  I had to replace the Li-ion battery after it sat unused for an extended period.  I decided to purchase the AA-600 because it had some more features than the 520.  Polar impedance measurements for one.  Replaceable AA cells for another.

The absolute best enhancement for my use is the time domain reflectometer.  It's done by wide-band sweeping of the analyzer and performing an inverse fast Fourier transform on the frequency/phase data.  It's all automated and takes about half a minute for the measurement.

Big deal, you might say.  Well ... this feature saved me some serious time/effort/expense when I had an unexplained screwy VSWR problem "somewhere" between my equipment and the tower-top connector on a run of LDF4 1/2" Heliax.  I had invited the tower crew over to work on it, but didn't quite know what to expect.  

I decided to try the TDR function and to my amazement it showed a perfect transmission line until 152.3 feet from the bottom end of the feed line.  After that point, the reflection display showed all manner of wiggly departure from 50 ohms.  The cable was 165 feet long and had some extra length I could sacrifice to make a repair.  The work crew pulled 15 feet up the tower and cut it off.  The TDR display then showed all was perfect to the open end.  A new connector was attached and all is well.  No more screwy VSWR.  The 15' cut off "bad" section measured bad when TDR'd during the post mortem on the ground.  No mystery anymore.

I didn't have to replace the entire cable.  It only cost a spare connector to fix the problem.  I would have never been able to find such an elegant solution without a TDR of some sort.  The addition of the TDR function to RigExpert antenna analyzers makes them number one in my book and well worth adding to one's tool kit.
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George Molnar, KF2T, Elmer

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There is, of course, no better starting point than scrupulously following any antenna's construction and installation instructions, and the use of high-quality transmission line.
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James Madden

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Thanks very much. I hear lots of transmissions here in Seattle and i have even talked to people a fair distance away on 20 meters inillinos forminstance. But im having a lot of problems making routine connections with people even though imhear them quite well. Any advice would be greatly appreciated. Jim