Re: [Elecraft] Antenna Analyzer (FA-VA4)
Simple. Connect the analyzer output to one antenna, the input to the other. Set the sweep range for that where you want to look at antenna coupling (usually one band for which the antennas are used). Make a sweep and tell the analyzer software to display S21 in dB. S21 is the gain of a device or network. 73, Jim On 12/3/2017 1:16 PM, Dick Green wrote: Jim wrote: Note also that this is a vector NETWORK analyzer. A NETWORK analyzer has input and output ports, so that in addition to impedance and TDR, it can also measure the response of any system. You can, for example, measure the effectiveness of filters, and the coupling between adjacent antennas. Jim, for those of us who haven’t used a network analyzer, how do you use one to measure coupling between antennas? 73, Dick WC1M __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
In this case think of the network analyzer as a transmitter with a receiver tuned to the same frequency. Before testing you connect the two together and normalize the receiver response to unity at each test frequency. Now connect the transmitter port to one antenna and the receive port to the other antenna. The response will be some fraction of unity, which can be presented as % transmitted, or more often in dB. Wes N7WS On 12/3/2017 2:16 PM, Dick Green wrote: Jim wrote: Note also that this is a vector NETWORK analyzer. A NETWORK analyzer has input and output ports, so that in addition to impedance and TDR, it can also measure the response of any system. You can, for example, measure the effectiveness of filters, and the coupling between adjacent antennas. Jim, for those of us who haven’t used a network analyzer, how do you use one to measure coupling between antennas? 73, Dick WC1M __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
Hi, That ought to be fairly straightforward. Connect one antenna to the the output port of the analyzer and the other antenna to the input port. Then set the sweep for the frequency range you want to test. AB2TC - Knut wc1m wrote > Jim wrote: > >> Note also that this is a vector NETWORK analyzer. A NETWORK analyzer has >> input and output ports, so that in addition to impedance and TDR, it can >> also measure the response of any system. You can, for example, measure >> the effectiveness of filters, and the coupling between adjacent antennas. > > Jim, for those of us who haven’t used a network analyzer, how do you use > one to measure coupling between antennas? > > 73, Dick WC1M > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto: > Elecraft@.qth > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to > lists+1215531472858-365791@.nabble -- Sent from: http://elecraft.365791.n2.nabble.com/ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
Jim wrote: > Note also that this is a vector NETWORK analyzer. A NETWORK analyzer has > input and output ports, so that in addition to impedance and TDR, it can also > measure the response of any system. You can, for example, measure the > effectiveness of filters, and the coupling between adjacent antennas. Jim, for those of us who haven’t used a network analyzer, how do you use one to measure coupling between antennas? 73, Dick WC1M __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
On 12/1/2017 10:30 AM, Wes Stewart wrote: What calibrations are you doing that take an hour? You can do a master cal with lots of points in 5 minutes. Yes. AND, more important, calibrations can be saved for standard measurement setups, so when you're always using a previous setup, there's no need to recalibrate -- you simply load the previous calibration. I use mine in the field all the time using a Win 10 touch screen tablet. The software is phenomenal. I've been doing network analysis since the days when the calibration curve was a grease pencil line on a CRT. I (my employer) bought one of the first HP8510s sold to a non-governmental agency. It cost IIRC north of $200K, was in a 4-foot rack cabinet and probably weighed 500 pounds. With an admittedly reduced frequency range, the VNWA3 is for all practical purposes the equal of the '8510 and I can hold it in the palm of my hand! Like Wes, I've been doing swept complex (magnitude and phase) measurements since 1982, first in the audio range, later at RF. I bought the VNWA3e about 4 years ago, and have found it to be the excellent that Wes describes. It has an excellent TDR function. Another important advantage of this unit over others is that it is self-powered from the USB port, so no external power is required. TDR can be VERY useful when troubleshooting an antenna or feedline problem, and the higher the analyzer can sweep, the more fine detail it can show. The VNWA can sweep to 1.3 GHz. Few analyzers the do TDR can sweep nearly this high. A wideband TDR sweep can find all the splices and many defects in a feedline. Another use of TDR is that it allows us to measure an antenna at the shack end of a feedline, find the electrical length of the feedline with the TDR feature, and then using Smith Chart software (free), subtract out the feedline to see the Z and SWR at the feedpoint. Note also that this is a vector NETWORK analyzer. A NETWORK analyzer has input and output ports, so that in addition to impedance and TDR, it can also measure the response of any system. You can, for example, measure the effectiveness of filters, and the coupling between adjacent antennas. These plots of bandpass filter response were done with the VNWA 3e. Note that you can display several views of the same measurement. These display SWR, attenuation, and reflection loss, and the markers show values within the passband and on other ham bands. http://audiosystemsgroup.com/BandpassFilterData.htm These data were used to generate this report that ran in National Contest Journal in 2014. http://k9yc.com/BandpassFilterSurvey.pdf With a good external frequency standard (I use a Bodnar GPSDO) it makes an excellent frequency counter and works as a limited function spectrum analyzer. Yes, and quite versatile in that mode. Inexpensive SDRs also provide limited spectrum analyzer functions, and some of them are quite good IF the user is careful to prevent overload and knows how to avoid false responses from aliasing. One other thing. On my 160-meter inverted-L antenna I receive a couple of AM broadcast stations at -3dBm. If I limit the lower sweep frequency to 1.7 MHz the VNWA3 is unaffected. I suspect some of these other boxes are not so resilient. This can be very important -- many analyzers get blown away by AM broadcast stations. Here are links to the mfr, SDRKits. The VNWA is NOT a kit, it is built and fully tested. You want the model 3E or 3EC with calibration kit and cables. https://www.sdr-kits.net/index.php?route=web/pages&page_id=29_29 https://www.sdr-kits.net/index.php?route=web/pages&page_id=68_68 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
What calibrations are you doing that take an hour? You can do a master cal with lots of points in 5 minutes. I use mine in the field all the time using a Win 10 touch screen tablet. The software is phenomenal. I've been doing network analysis since the days when the calibration curve was a grease pencil line on a CRT. I (my employer) bought one of the first HP8510s sold to a non-governmental agency. It cost IIRC north of $200K, was in a 4-foot rack cabinet and probably weighed 500 pounds. With an admittedly reduced frequency range, the VNWA3 is for all practical purposes the equal of the '8510 and I can hold it in the palm of my hand! With a good external frequency standard (I use a Bodnar GPSDO) it makes an excellent frequency counter and works as a limited function spectrum analyzer. One other thing. On my 160-meter inverted-L antenna I receive a couple of AM broadcast stations at -3dBm. If I limit the lower sweep frequency to 1.7 MHz the VNWA3 is unaffected. I suspect some of these other boxes are not so resilient. Wes N7WS Not associated with any of the players who designed or built this thing. Simply a very satisfied customer. On 12/1/2017 9:16 AM, Ignacy wrote: VNWA3 covers > 1300 MHz and costs about $600 but needs a computer. Often requires multiple calibrations requiring an hr. Has two port for filters and beam testing. I use it only when nothing else works. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
I have one more suggestion. I have a MiniVNA Tiny, expensive at about $600, but it is a full two port Vector Network Analyzer in a 2.5" X 2.5" X 1" box connected via USB. It has both a computer app and a phone app to run it. I have taken it out in the field where I would never consider taking a 75 lb VNA. I have used it to analyze antennas, filters, transmission lines and to characterize caps and inductors over frequency. 73, Mark W7MLG On Fri, Dec 1, 2017 at 9:16 AM, Ignacy wrote: > The choice of analyzers is not that simple unless cheap price is the only > factor. > > I have four analyzers: Rigexpert 230Pro, FA-VA4, VNWA3 and Mini60. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to marklgoldb...@gmail.com > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
The choice of analyzers is not that simple unless cheap price is the only factor. I have four analyzers: Rigexpert 230Pro, FA-VA4, VNWA3 and Mini60. Rigexpert covers up to 230 MHz and costs about $500. It is the easiest to use and has the most functionality. Less accurate because it does not have OLS calibration and is pretty big, but new models (Zoom) have calibration and are much lighter. Seems rain resistant. Coax testing for short and length is a blessing. I use it most of the time. VNWA3 covers > 1300 MHz and costs about $600 but needs a computer. Often requires multiple calibrations requiring an hr. Has two port for filters and beam testing. I use it only when nothing else works. FA-VA4 works up to 100 MHz and is very accurate after good calibration (included 50 Ohm load is not too good). Light but not the smallest. Getting things done takes many buttons. Not waterproof. Also. soldering is tricky and I wonder whether bad soldering will show up one time. I use FA-VA4 for portable measurements where accuracy is important. For instance impedance of inv L on 160m. Measure impedance, prepare appropriate coil, and no extra fine tuning needed. Also very useful to measure properties of toroids across frequency. I also have mini60 that works up to 60 MHz, is very small, can be charged via USB, and interfaces with Android phone, and costs $100. SWR accuracy is good but X is not. I leave it for travel. -- Sent from: http://elecraft.365791.n2.nabble.com/ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Antenna Analyzer (FA-VA4)
John, I saw that one on FunkAmateur/Box73, they sell the kit. What appeals me is the price (155 euro), the simplicity the way it can be built, the features, apart form being a nice graphical analyzer it's much more like a signal generator from 100 kHz to 100 MHz. It's readable in direct sunlight due to it's LCD type (like te one on a K3 even the same backlight color) And the power supply: it uses two AA cells. I have it and I can say: Highly recommended. 72/73 Peter - PA0PJE PS No connection to FA/Box73... Op 2017-12-01 13:57 schreef John Harper: I highly recommend this one - cost effective, easy to build and compares favorable to more expensive models: https://ae5x.blogspot.com/2017/10/new-antenna-analyzer.html More here: https://ae5x.blogspot.com/2017/11/a-brief-comparison-of-two-antenna.html 73, John AE5X __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to pa0...@xs4all.nl __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
