devicelab
Whacker Extraordinaire
Here's a really good VNA primer document. Don't let the graphics scare you -- it's written very well...
Larsen TRI-Band VNA Sweep (Part Deux) + Laird Scanner and COMPACtenna SCAN III
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Here's a really good VNA primer document. Don't let the graphics scare you -- it's written very well...
devicelab
Whacker Extraordinaire
Ah gotcha. There are USB solutions but you still need a PC laptop or tablet to use them. The NanoVNA is very portable and its built-in lithium battery seems to last a long time. Charging is via USB-C cable and fast.
n1nte
Member
Yes, I have used the NanoVNA as a method for tuning VHF/UHF mobile antennas. Works great for that purpose among its many other uses.
The new Larsen 150/450/758 arrived today. Results are slightly better than the older Larsen, but nowhere near as good as the results Devicelab plotted. No surprise as my NMO mounting type and location on the corner of the hood is not an optimum ground plane for the Larsen to perform.
devicelab
Whacker Extraordinaire
Do you have a VNA to sweep it? I'd be curious to see what it looks like...
I do and did sweep them, but my VNA is different from yours and does not plot out the markers. I do want a VNA that will handle higher frequencies and may end up purchasing the same model you have. If so, I will plot the antennas...which won't mean much based on what I conveyed about my compromised ground plane location. For $50 the Larsen 150/450/758 is hard to beat, with a proper ground plane.
Here's my Larsen sweep (along with a Browning)...
forums.radioreference.com
Larsen Tri-band antenna
Well, I've been running it the last few weeks here in the Sacramento area. It picks up all the repeaters great on both VHF and UHF. I have not really scanned 7/800 or even 900 on it yet, though I will when I get a new scanner. As expected simplex range greatly diminished. It really is great...
devicelab
Whacker Extraordinaire
Slightly off-topic but have you guys tried this hardware? KC901S+ 4GHz Handheld Network Analyzer | DEEPACE
Supposedly it's very high quality and really accurate. There are videos on YouTube from knowledgeable reviewers.
Supposedly it's very high quality and really accurate. There are videos on YouTube from knowledgeable reviewers.
I have not heard of the KC901S+, but I am not in the radio business. I use mine for fun, but need gear that works for testing and tuning antennas, filters, duplexers and the like.
I use this small one for checking/tuning antennas, filters, and to even tune a UHF notch duplexer.
To tune a proper BpBr duplexer I use an Agilent E6380A that is on indefinite loan. If I did not have that I would favor two others. First, the Rigol DSA-815 with the tracking generator to handle my amateur needs. It is significantly smaller than the Agilent 8935 series. Still, either of those price wise are similar to the KC901S+. The other I would look at is one of the HP 8560 models for around that same price. Still, what matters is whether you need 4GHz and or need 4GHz in a small sized package.
I use this small one for checking/tuning antennas, filters, and to even tune a UHF notch duplexer.
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To tune a proper BpBr duplexer I use an Agilent E6380A that is on indefinite loan. If I did not have that I would favor two others. First, the Rigol DSA-815 with the tracking generator to handle my amateur needs. It is significantly smaller than the Agilent 8935 series. Still, either of those price wise are similar to the KC901S+. The other I would look at is one of the HP 8560 models for around that same price. Still, what matters is whether you need 4GHz and or need 4GHz in a small sized package.
mmckenna
I ♥ Ø
I just received the Larsen NMO-150/450/800SF and a Larsen NMO-150/450/758SF. My plan is to take them home along with my antenna analyzer and compare the plots. I'll share them here once I've done that.
Ubbe
Member
Remember to calibrate out the coax if you only want to see the result from the antenna. Or use the same type and lenght of coax that you later will use if you would like to see what the scanner sees at its antenna port. And the antennas needs a proper ground plane to get the proper impedance.
Then stop a scanner at 150/450/800MHz and run the analyzer on the scanners antenna port to see how well matched it is.
/Ubbe
devicelab
Whacker Extraordinaire
From my experience (and recent sweeps) this is largely a non-issue -- especially when dealing with mobile setups. I don't think too many people will have coax runs over 25ft in length.
For $50 the Larsen 150/450/758 is hard to beat, with a proper ground plane. If the mounting location lacks a ground plane, the ScanIII performs better in my testing. I would think that most mounting locations would have a suitable ground plane, so the new Larsen would win. Additionally, the ScanIII performs well in the frequencies it advertises, but the Larsen is a bit better outside of its advertised freqs than the ScanIII.
These two antennas are apples and oranges to me. Suitability depends on the mounting location and the ScanIII makes that point clear in their advertising. If I had to choose one over the other I would select the Larsen 150/450/758. The bonus is it being half the price. Still, I do not plan on selling the ScanIII, again the right tool for the right job.
These two antennas are apples and oranges to me. Suitability depends on the mounting location and the ScanIII makes that point clear in their advertising. If I had to choose one over the other I would select the Larsen 150/450/758. The bonus is it being half the price. Still, I do not plan on selling the ScanIII, again the right tool for the right job.
I narrowed it down to the newer Larsen tri-band and the Compactenna Scan-III. I wound up buying the Scan-III upon recommendation of the guys at HRO.
The first test was the drive home, which was about an hour away from the store. Right off the bat, I noticed that I was receiving transmissions outside of the store that I lost approximately half way down on the trip to the store. Everything was much clearer.
The second test was at our home. I mounted it in a window of our first floor apartment and immediately was getting better reception and could now receive the Philly TRS, which I could not do before.
I can't compare the Scan-III to the Larsen, because I don't own one, but I can highly recommend the Scan-III. It outperforms any other other antenna that I have either on my vehicle or in the apartment.
The first test was the drive home, which was about an hour away from the store. Right off the bat, I noticed that I was receiving transmissions outside of the store that I lost approximately half way down on the trip to the store. Everything was much clearer.
The second test was at our home. I mounted it in a window of our first floor apartment and immediately was getting better reception and could now receive the Philly TRS, which I could not do before.
I can't compare the Scan-III to the Larsen, because I don't own one, but I can highly recommend the Scan-III. It outperforms any other other antenna that I have either on my vehicle or in the apartment.
devicelab
Whacker Extraordinaire
So they convinced you to spend 2x your money and boy you sure feel satisfied... well, there's one born every minute -- I suppose. ;o)
Can you post sweeps of the Larsen 758 and the Scan III without using a ground plane for each? If you could use the same marker points on your initial sweep it would be helpful for comparison. For the reason why, I think rgchristy is using the Scan III at a window without a suitable ground plane. That method is something others are doing as well, based on various posts I have read, regardless of the antenna manufacture or type. Thank you.
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I have three different COMPACtennas here and they perform better than many other antennas that are larger. You get what you pay for.
devicelab
Whacker Extraordinaire
I would but I no longer own the Scan III antenna.
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