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Under SWR Single sweep, based on this practically useless manual, how do you tell which side is plus (+) and which is minus (-)??? Thanks.....Ken

Dear FA-VA5 users, For those of you who may not be so familiar with antenna impedance measurements, here are some points to consider: If a reasonably well-matched antenna is measured via a long feeding coax cable, things are pretty straight forward. You connect the coax cable to the FA-VA5 via suitable adapters and measure in the format of choice. You should see a low VSWR at the antenna's frequency(ies) of operation and when changing the FA-VA5 frequency progressively in suitably small steps you should see a departure from the good VSWR in both directions of frequency change. Measuring the two frequencies where VSWR = 2.0 (outer VSWR band edges) is good practice and noting them down for future reference is even better. Measurements at the feedpoint of the antenna, say the center of a halfwave wire dipole, require a bit more attention. If no balun is available, you can still do meaningful measurements if you connect the FA-VA5 via suitable adapters or a coax socket connected to the dipole wires. In this case it is necessary to not touch the FA-VA5 while you are reading the measured results. The reason is that the FA-VA5 housing carries an RF potential and therefore your hands may load and detune the antenna and thereby falsify the measurement. Using a known good 1:1 balun symmetry transformer is best practice and the "hand problem" should not exist or be negligibly small. A good test of measurement accuracy is simply by "hand-on - hand-off". You might argue that the direct measurement without balun can't be right because the antenna is symmetrical (2 wires) whereas the FA-VA5 is unsymmetrical (BNC socket). That is true in principle but because the FA-VA5 is "electrically small" - at least at HF frequencies - the measurement is still valid and fairly accurate. Vertical antennas which are excited against ground or radial wires can also be measured with the FA-VA5. If a coax connection is present, it's as simple as 1 2 3. Direct connection via suitable adapters and we are done. If the antenna wire is usually connected to a tuner, then we need to disconnect the antenna wire and insert a coax socket with the outer metal body of the socket firmly connected to the grounding terminal that is used during antenna operation. That ground connection must be as short as possible because otherwise it will falsify the measurement results because of its inductive reactance. Alternatively, I sometimes use a simple "BNC-male to banana" adapter for measurements are HF frequencies. A guiding principle should always be that an antenna is a "closed-loop circuit". By that is meant that for example a quarterwave vertical antenna extends from the radiator back to ground (or radials) via the electric near-field and on the ground, the RF current flows back to the feedpoint, thus forming a "closed-loop". This also implies that if we have a poor conductivity ground, the real-part of the antenna impedance increases. Whereas a thin quarterwave vertical antenna has an impedance of about 37 Ohms (half that of a halfwave dipole) the real-part of the impedance increases significantly if the ground is bad. Good luck 73 Dieter, VK3FFB

Hello group, I am considering purchasing a fa-va5. I will mainly use it for antenna and trap meaurements. But: since it is a one port device, is it posssible to do some measurements on low/high/band pass filters? Or do I need a 2 port device? Thanks for your advice Jeroen PF1JM

I've just found the correspondance about measuring CMR of CM filters, and the Impedance option menu(s). However I haven't been able to find advice for a test jig or connection method for doing CMR measurements. I thought I would have to acquire a VNWA3 to play with for these properties. Is there any information available, or can Someone send that to me please? Toys that continually make us think harder and harder hopefully keep Mr Alzheimer at bay! 73 , Peter

Having easily convinced a friend to also purchase an FA-VA5 I remembered that I had to teach myself, and then him, to use and drive the VNWA program. He wants the PC connection usage to record the changes he finds(!). His VA5 has been assembled and its working is indistinguishable to mine, except for the newer firmware. The fun, or frustration, started when I installed the VNWA prog and assumed it would be just as easy as with the programs for my SiteMaster or AIM4170 ! I have installed VNWA ver. 36.07.9.0 into a Win7 64bit PC, and the firmawre in the VA5 is SW1.09. I've sorted out the USB interfacing and this activates properly some of the time. For the remaining 60% or so of the time I need to go to Options>Setup> and press 'Rescan'. Only then will the connection be made/come active and I can 'drive' the VA5. Note the 'connect' sign does not show in green as per fig.57. This was when the Frustration really set in- 1) The VSWR trace first came up as blue lines across the top of the graph, somehow I found out how to alter the vertical scaling and get them down towards the bottom of the graph. 2) The red Smith chart trace was plotted in less than the RH quarter of the Smith chart and I couldn't find how to get it displayed over the full 'Smith area'. Today it is being drawn in the full 'Smith area' and I don't have any idea what change(s) [of mine] brought this about. 3) I can't find the pdf HELP file at the SDR-Kits website, Maybe they have some server problems cos other parts of the website work. Perhaps can someone assist and direct me to another source? 4) When the blue or WHY colour traces are drawn not all of the old trace is wiped away. This is important for e.g. seeing trends from component changes or adaptions but is there an easy to use button to undraw the old trace when going to a completely new measurement with the same settings 5) I havn't seen an indication on the front page that I don't have the connection to the VA5, I think this could have helped me at first, And will most certainly be a help to my friend, perhaps just a green spot as a positive signal? So far, my difficulties are mainly in finding how to set the scales and scalings properly. I wonder if it is possible to have some initial 'settings files' that could be loaded up and then one goes on to develop ones own settings from these? This could also obviate a critique made by Dave Kasler in one of his video shorts. Does anyone have some settings files they can share with me? I rather expect this method will be a benefit in helping my friend with his VA5. I'm aware that the flexibility of the scale setting and scaling, and displacemnt, makes the package very useful and powerful tool, doing a similar data adaption with SiteMaster files required some exacting manipulation. And I'm intrigued by the possibilities provided, it's just i haven't yet figured them all out. Further questions are about the significance of the 'S11' and MEM1-2-3 areas- OK, only Scatter plots 1-1 are developed with a single port VNA, but what does the application of S11 to Mem1 area mean?

This topic groupes questions about spare parts for replacements and repairs: 1) Sliding switch After intensive usage it may happen that the sliding switch (power) does not work any longer as expected. The switch was stock material used by the manufacturer. Either you contact your FA-VA4 / FA-VA5 supplier to send another switch, or you use a different one. I designed the wholes for the switch a little bit bigger than needed. A high quality switch should fit in: APEM SS 25339 N or with a longer actuator APEM SS 25339 N6 should both fit in. But please check the sizing before ordering. Mouser datasheet: https://www.mouser.de/datasheet/2/26/PCB-slideswitches-serie-25000N-1511380.pdf

Dear FA-VA5 users, I am pleased to report that we now have 131 members in our FA-VA5 group. Clearly the popularity of the FA-VA5 is increasing. The main reason is probably measurement accuracy and instrument versatility. Group activity is quite low which probably means that most of us are not in need of help in connection with using the FA-VA5. If you have any unresolved problems, please feel free to post them in the group. with best regards & 73 Dieter, VK3FFB

the second VA5 i built mostly does not power up on batteries but powers up just fine via USB. i have used a continuity buzzer on the slide switch and instead of a definite on-off action, the buzzer sends CW at about 28 wpm. :-P in other words, the switch contacts are super 'bouncy' and i think that's why the VA5 does not power up properly on batteries. may i have the manufacturer and part number for the switch so i can purchase a replacement from a domestic (US) source? i have identified an almost exact equivalent switch: E-Switch EG1206A https://www.digikey.com/en/products/detail/EG1206A/EG1917-ND/251334 nevertheless, i would like to have the original part information in case there is a better alternative. thanks! = 73 =

I would like to wish healthy, safety and happy New Year 2021 to all over here. 73 - Petr, OK1RP

Dear FA-VA5 users The group has grown steadily at an average rate of 12 new users every month. So we welcome all members who recently joined the FA-VA5 user group. A number user questions have been answered and problems were resolved. Indeed, the FA-VA5 is a game-changer in terms of accuracy and versatility. All commercial analysers need calibration (SOL - short-open-load) and so does the FA-VA5. Luckily for most standard applications, the master calibration (SM50) is sufficient. Master calibration data is saved in the unit and does not need to be repeated after the unit was switched off. However, other calibrations are volatile and need to be repeated after switch off. Please feel free to post any questions or reports on interesting applications here. All questions will be answered speedily. All reports are read with great interest. Analysers, like the FA-VA5 have brought, what are probably "new terms" into the ham radio hobby. Most hams know well what VSWR means but perhaps not so well how VSWR relates to impedance. A few posts exist here to explain these relationships. Check the "Files" region to find them. Some users - including myself - were troubled by unsuitable USB cables when using the FA-VA5 with the fine VNWA software on a PC or laptop. Therefore I ask all new users to *keep in mind that a proper USB cable is required with all USB data wires*. Unfortunately, many USB cables are only good for charging devices and don't have the actual USB data wires ! :) The fact, that the FA-VA5 lights up when a cable is connected does not mean, that the data wires exist in the used cable. thanks & a happy and healthy festive season to all Dieter, VK3FFB

Hi Meanwhile a local friend of mine had exactly the same USB cable related problem with the VA5 as I had. So, it is important to tell all VA5 users that it must be a proper USB cable. It is not enough to have a cable with a matching mini-USB connector. It must be a proper USB cable. Many cables are just for charging purposes and do not have all USB signal leads. So, if you have had issues with the PC operation using the VNWA software, chances are you had a bad USB cable. The VA5 will still light up and show USB mode on the screen, but the VA5 will not be recognised by the VNWA program. 73 Dieter, VK3FFB

Hello, I am just a FA-VA5 new comer, but have a very good background in VNA uses. All have different protocols and menus. I just need to learn how each one works. I would like to understand the protocol of the operational software and in particular the difference between SETUP and the rest of the menu functions. 1.The setup menu appears to be one where you set the overall functions of the FA-VA5. Once selected they control all of the operation and display functions. Is this correct? 2. The rest of the menu options are only relative to the selected function. So any setup limits, speed, display, etc are controlled by the SETUP and any test functions performed abide by the SETUP selected protocol. Is this correct? This brings me to what I think is an application "bug". When you SETUP the Z range to 200 ohms vs 50 ohm source that limit is 4:1, When using the Z sweep it displays the correct limits of +/- 200 ohms. When you move to SWR sweep, the range on the display is still defaulted to 10:1 SWR. Why is that so? I would appreciate any comments to help me learn. Thank you for your interest. Mel, K6KBE

One of the bugaboos is what happens when something goes wrong in the VNA? Take a second harmonic out of range for example...... The SOL will not tell you that you have a problem. BUT the measurements will be invalid. SO, I built up a reactive load to test the linearity of the device at 10 MHz. How about a simple test like confirming the linearity? I built up a serial network of a SMD 50 ohm resistor in series with a selected SMD 318.5 pF cap to ground on a PCB male plug. Well, at 10 MHz, that reads 50-j50. Scale up and down 5 MHz and see -j100 and at 20 MHz -j25 and the j better track, if not you have a problem......... Try it some time. Mel, K6KBE

This topic is for all questions and comments related to the assembly of the FA-VA5.

Is it possible to set the analyzer to sweep the entire HF ham band (1.8 - 30Mhz) for SWR? If so, how? -- 73, Greg, KM5GT

This topic is about using the USB port for data transfer.

Hello all, First post here after much "trying" with this VA5 program, literally, over the past year. May be in over my head with this instrument! Trying to set it up so I can do a test sweep from 3 to 30Mhz on this EFHW transformer I built with two 240-43 toroids. I've done the five band thing, I'm ok with that but the computer version leaves me in the dust. I've got the display to read 3-30Mhz at the bottom with the center frequency and span but it just scans across the screen with one single vertical bar. Just to many parameters for this old brain to compute. Beginning to think I should have tried a Rig Expert analyzer. The manual or even the programs "help" file really doesn't help. I think if the program was just for this analyzer I would be ok. I see these nice displays with frequencies and SWR's.......not here!! Step by step instructions would be great!! Thanks for any input......!! Ken, W2GIW