VIA User`s Manual V1.00
Contents
1. AUTO mode but this time tap the Manual button from the VIA Setup screen than tap the Plot button and tap the VSWR button After the screen changes to the Chart screen rotate the Manual Control knob in a clock wise direction to plot the curve Continue turning the knob until the frequency displayed stops changing This should equal or be very close to the Stop_ Freq setting 7 300 000 Hz This completes the Manual creation of the plot for the device under test To avoid cluttering the display during plots the Frequency cursor is parked just off the left edge of the display and as in the AUTO mode rotating the Cursor Control will move the vertical line across the screen displaying the frequency By the way if both Control knobs do not increase their function to the right on the screen when turned in the clock wise direction please see Control Reverse wiring Function in the Trouble Shooting sections of this manual To return to the VIA Setup screen tap the Return button from the Chart screen then tap the Setup button from the Tabular screen This completes the VSWR test of a 40 meter dipole The same process is used to test any other antenna by setting the Start and Stop Frequencies and connecting the antenna to the VIA and running the test Multiple band antennas may also be tested by just entering the lowest frequency for the start frequency and the highest frequency of the highest band2. However the design of the VIA board layout has taken this into account The part placement and solder joints have been spaced apart and extended slightly to help in the hand soldering of components It s highly recommend that research is done on SMT soldering techniques before attempting the VIA assembly Also having the right tools will make a big difference in the assembly like magnification devices good lighting board holding devices quality Soldering Iron with the capability to use very small tips etc Check out all the other documentation on the web Just enter KSBCQ in the search engine then click on KSBCQ amp K5JHF Kits QSL net and scroll down to Kit 25 and follow all the other documentation to help in assembling this quality Vector Impedance Analyzer Thank you again and we hope you find many many uses for what we believe to be one of the finest tools with even greater possibilities in the future History This project was a collaborative development adventure of Milt Cram W8NUE and Kees Talen KSBCQ They decided to develop a project utilizing some very good products like the STM32F407 Discovery board which contains plenty of microcontroller capability and features with available free Development Tools and at a price being right for this type of project Milt drew on his SDR2GO firmware experience and code he used for the NUE PSK Digital Modem and also the more recent STM32 SDR code He decided to base the d
3. Verify there is a good connection between the other side of R9 and R10 to Pin 6 of U1 Reassemble the boards and while turning on the power watch the screen If everything above was verified the screen should update quickly Remove the leads and you are ready to go No display when power is applied A short on the 3 3 Volt line in the VIA will cause the screen to not display 3 3 Volt check The 3 3 Volt is supplied from the Discovery board and needs to be checked for a steady level voltage This can be accomplished by attaching the ground lead from a DVM to the chassis and checking the voltage on pin 5 amp 6 on P2 on the Discovery board or by using a scope to see the 3 3V line for fluctuations Look for the Voltage markings on the Discovery board Any fluctuation of the voltage means there is a short somewhere on the VIA board This will require a thorough check of the VIA board and its 3 3V line connections Turn off the power remove the power connection from the VIA board and remove the Discovery and VIA boards from the stack and don t forget to unsolder the leads to the BNC connector While checking components it s advisable to use high magnification and good lighting to inspect between leads for shorts Areas to check U6 U5 U1 Pins 7 to pin 8 Pins 7 to pin 8 Pins 6 to pin 7 Across C1 across C4 across C6 Pins 26 to pin 28 across C9 and C10 Do a detailed visual inspection of all the areas mentioned above and re s
4. that means there is a bad solder joint in one or more of the attenuator leveling components Remove the VIA and re solder C20 C22 R12 R15 and C24 and make sure there is a connection between C24 and Pin 1of U3 and C22 and Pin 2 of U3 Again this can be checked using a DVM Reassemble the unit and apply power and repeat the measurements as stated previously If a signal is detected on C20 C22 and C24 it means the attenuator circuit is now working However if there is no signal on C15 it means U3 may still have issues Remove the VIA and double check the solder joints on all the pins of U3 and especially on Pin 4 of U3 Re solder C16 just to make sure it has a good connection Before the unit is reassembled check that there is a short between Pin 4 on U3 and one side of C15 Again just checking for a broken trace between the two points before the unit is reassembled Again use the DVM to ensure the signal path between the parts is good Put the VIA back together and turn it on Now check for signals at all test leads If there is a signal at C20 C22 and C24 but still no signal at C15 and all the solder joints are okay on U3 this means U3 is bad and needs to be replaced After replacing U3 and reattaching the five test leads put the VIA back together and turn it on Pay close attention to the screen timing If the screen comes up quickly then you re finished trouble shooting and can now Start enjoying the use of this gre
5. 24 TAM MENG Car senini narenn actus aE E TOE 24 Tabular Screen issues shes E SEE EE E EAE E E AE E E EEE S E E ETT 24 Very low readings for V1 V2 and IF E Sig ENAA EEE EAE PETI A tastes EEE S EEE E eat 25 Encoder Reverse wiring FUNCTION cosi8 cee ee a ee a ena 25 Section 5 Firmware updates YAP AH TT alco estes e col 6 E eer E ra op tr Ee Ene Oe E E EEO CERT SOR OER eee PO 26 Bill Sepulveda KSLN Ver 1 00 Page 2 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Introduction Welcome and thank you for your interest in the Vector Impedance Analyzer VIA We sincerely hope that it has been an enjoyable and enlightening learning experience to build this kit It s understood this is not a kit for the novice or intermediate kit builder However with research on Surface Mount Technology SMT a good set of tools and with some practice this tool will turn out to be an important tool for any electronic enthusiast It s a very high quality tool with great flexibility in how it s completed to the builder s expectations When this kit is finished it will contain more functional capabilities than products costing much more which have less functionality Plus the Kit contains the capability of uploading new Firmware to stay up with new features and capabilities Please understand this is a state of art technology tool using the latest in SMT devices With parts that may not be the easiest to assemble by hand
6. Analyzer Operations Manual Type text Section 3 Technical Definitions SmithChart The Smith chart invented by Phillip H Smith 1905 1987 is a graphical aid or nomogram designed for electrical and electronics engineers specializing in radio frequency RF engineering to assist in solving problems with transmission lines and matching circuits Use of the Smith chart utility has grown steadily over the years and it is still widely used today not only as a problem solving aid but as a graphical demonstrator of how many RF parameters behave at one or more frequencies an alternative to using tabular information The Smith chart can be used to simultaneously display multiple parameters including impedances admittances reflection coefficients San scattering parameters noise figure circles constant gain contours and regions for unconditional stability including mechanical vibrations analysis The Smith chart is most frequently used at or within the unity radius region However the remainder is still mathematically relevant being used for example in oscillator design and stability analysis Impedance Impedance is the complex valued generalization of resistance It may refer to e Acoustic impedance a constant related to the propagation of sound waves in an acoustic medium e Electrical impedance the ratio of the voltage phasor to the electric current phasor a measure of the opposition to time varying electric current in
7. an electric circuit o Characteristic impedance of a transmission line o Impedance accelerator physics a characterization of the self interaction of a charged particle beam o Nominal impedance approximate designed impedance e Mechanical impedance a measure of opposition to motion of a structure subjected to a force e Wave impedance a constant related to electromagnetic wave propagation in a medium o Impedance of free space a universal constant and the simplest case of a wave impedance Admittance In electrical engineering admittance is a measure of how easily a circuit or device will allow a current to flow It is defined as the inverse of impedance The SI unit of admittance is the Siemens symbol S Oliver Heaviside coined the term admittance in December 1887 Admittance is defined as 1 Lr 4 where Y is the admittance measured in siemens Z is the impedance measured in ohms The synonymous unit mho and the symbol U an upside down uppercase omega Q are also in common use Resistance is a measure of the opposition of a circuit to the flow of a steady current while impedance takes into account not only the resistance but also dynamic effects known as reactance Likewise admittance is not only a measure of the ease with which a steady current can flow but also the dynamic effects of the material s susceptance to polarization Y G jB where e Y isthe admittance measured in Siemens e Gris the conductance measured in Siemen
8. are talking to each other and that s goodness We can stop trouble shooting and start using the unit However if the Splash Screen is still taking 20 seconds or so there is something else wrong Again remove the VIA and this time check for signals on the VIA This will require the use of a Scope to detect the signals Or even a radio that has the capability of tuning to 12MHz To start let s see if we have a 12 MHz signal present on the VIA 1 12 MHz Oscillator U4 Check Solder one end of an 8 inch piece of 30 gauge wire to the side of R7 that goes to pin 1 of U1 TLV320AIC3204 Put the VIA back together and turn on the power If a radio is to be used to detect the 12 MHz signal set the radio to 12 MHz and set the unit close to the radio If the oscillator is working its signal will be heard in the speaker Make sure you have the volume up If you don t have a radio and have a scope turn on the scope and connect the probes ground lead to the chassis and the probe to wire coming off of R7 and adjust the scope to find the 12 MHz signal If the signal is present on the radio or displayed in the Scope this section of the circuit is working properly If there is no signal present at this point remove the VIA from the assembly and double check the solder joints again Retouch all solder joints on U4 and make sure there are no shorts between pads Put the VIA back together and turn it on Try it again and if still no signal
9. for the stop frequency How to do Tests With the start and Stop Frequency parameters set different tests may be made with the VIA by just selecting the type of test SmithChart Impedance Adimittance ReturnLoss ReflCoeff and VSWR Bill Sepulveda KSLN Ver 1 00 Page 11 Type text AQRP Vector Impedance Analyzer Operations Manual Type text SmithChart Creating a Smith Chart of an antenna may be accomplished by simply 1 tapping the Return button from the previous chart screen 2 Tap the Plot button from the Tabular screen The next screen will display which test to select 3 Just tap the SmithChart button and watch the magic That s if it s still in the Auto Plot mode Each type of chart may be created by these same steps just select the type of profile as the last step Tabular screen Impedance To create an Impedance profile select Impedance as the last step Tabular screen Please note when conducting an Impedance test there are two lines and scales the White line corresponds to the scale on the left side of the screen which is for the Resistive Part of the Load Impedance and the Green line corresponds to the scale on the right side and is for the Reactive part of the load impedance Use the Cursor Control to find where the white line intersects the 50 Ohm line on the left scale and the Green line intersects the Zero line on the right scale This will result in the opti
10. sab oaeaes 12 Admittance Measurements ccccccccsssssccseseseecesseceecssssecescseeeecessseseccsssuscesesuaeecesensseecesseetecesseeecesentaees 13 ReturnLoss MEASUFEIMENES isccencssstcvexvoses cased ciated deca siasiactadud lacwavsuateandae Gieananiae tauseaaded ovina tacadinead ot ese emad etek 13 PRETICOST COA TESNE zeonnn telemded sa tie re A arma eiaweteaBenduaes whaatbantaeeudaends 13 Other Functions e seaciraetenss eels aa aR a a seattle E E aa sseeaeeteeeantaaes 15 Encoder Knob functions E sc fete gu Acees fuss eh Aa late bolt Racin ales ua tus acl 15 Typical values for V1 V2 and IF ro E A E EE ET E astute loved E eGectes OEE E 15 Section 3 Technical Definitions OMACHA 16 Impedance earna A E AE cerca binactacd Cavalbthae diet 16 AdimMtta NCE heera en mT T A E eae oe 16 Return OSS henn a O a eaceesenaiee caahoat teaccat desea tena ne 17 PR OTIC O ST cnan sire ata cisiacien lees E ce a isc Savas eB ace E e asec eae each aa 17 Section 4 Symptoms amp Trouble shooting Splash Screen turn on timing ISSUING S28 ccedecicottsededesdeciveti ads leaded eealess Siveadeacewoseayneesddoabates unanialloasanensesantioacenleatec 19 No display when power is AD PNNC sos ccsescaccesdeerecesiasntacranar dean olvassddvndsbasdsaavactepeaush beseuay austen 23 Start Stop Step Dwell not being SAVE 0 0 0 ec cccsseseceeceseseaeecescsseeeceecesseeaeecescesuaeaeecesesseaeeeeeeseseeneees 24 Han Inthe Cak 1 od 9 ge ee eee eee eee
11. takes longer than two to three seconds to display the Splash screen there is something wrong in the assembly of the VIA board It usually means that the components are not talking to each other and there s either a bad component or solder joint issue Please remove the VIA and check the solder joints You may just find one that looked like it was well soldered but did not make a good connection If the unit has no display at all see the No display when power is applied in the Trouble Shooting section of this manual After visually checking ALL the parts and touching up ALL the solder joints re assemble the unit and apply power The sequence as mentioned earlier should occur If not then there is still something else to discover See the Splash Screen turn on timing issue in the Trouble Shooting section of this manual for further assistance If the Screen Calibration was not made because of initial issues and the unit is now working it s easy to go back and do the Calibration Screen Just push down both Control knobs at the same time until they click and turn on the power Hold the Controls down until the Calibration Screen is visible Then release the Controls At this time go through the screen calibration and when instructed tap the screen three times in quick succession to save the touch screen calibration If all parts are communicating the three tap screens should change quickly Then the screen will revert to the VIA Set
12. the screen will 5 755 pF indicate the function of the data being saved and the screen will revert back to the VIA Setup screen Bill Sepulveda K5LN Ver 1 00 Page 9 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Using the VIA to make measurements VSWR Measurement using the Auto Plot mode To create the chart of the 40 meter antenna example tap the Auto button in the VIA Setup screen and it will change to the Tabular screen showing some figures in each of the different fields like the ones shown below Tabular Screen Please note there should be numbers showing up in all the fields in the Tabular screen and especially in V1 V2 and IF_Sig fields Oh and yes there must be a load connected to the VIA for it to read correctly Please connect the antenna to the VIA If the fields do not show any varying numbers please refer to the Tabular Screen Issues in the Trouble Shooting section for more help If everything is reading sort of like in the example on the right above and the fields are White and Green tap the Plot button This will move to a screen to select which test is to be made on the device connected to the VIA If some of the fields are shown in the color RED there is likely some parameter which has not been set Please check the above procedure again and check Typical values for V1 V2 and IF_Sig in the Other Functions section
13. Austin QRP Club Vector Impedance Analyzer Operations Manual By Milt Cram W8NUE amp Kees Talen KSBCQ Type text AQRP Vector Impedance Analyzer Operations Manual Type text Table of Contents Section 1 Introductio enen nce aac tu Sac aaa eae od eda oe aac ea odie dctsia a se adr aamesen meee HTO soe spcctte strobes veces to aang aces senate ecc wns Suh eats E te eae ace E thames naaenree cama a DESIBM Features eaea a E E at en ea arene wm BP UU W THEORY OF Operation Snader E T aeons tease Re ee Section 2 Lers T a d 11 0 De Re Fo a en nO A ee RE ee TN Ree nae era 6 Screen 111 210 1 9 ON FR Rn ee 6 FEO CUCINCY SetuP eiaassrae ceca ec oa eats E A ae eens 8 VIA Cal Set eae eee nee erence re Pen ee Po ene De reer ee ere eee eee en ree 9 Using the VIA to Make MEAaSUFEMENMKG ccescsccessssseecesessseecesssecescssseeceseusescesssecescuseecessaeseecssaeeeeseeesaaeseess 10 VSWR Measurement using the Auto Plot mode ccc cecesssccessssseecessseceecesssecesceeseeceseseseecesuesessssaeeessessaeees 10 Test performed by the VIA ede EEN IET AEE E E AE AR E AEA A eaten E EA 10 VSWR Measurement using the Manual Plot Mode APEE E E E AN E E E AE EN 11 HOW todo TeSt zaari e a a a e N N 11 SmithChart Measurements ueeeseneeseesesesesseseresesrresssrresssrresssrressreressrtresseressrteesseeressreressreressreressreere 12 Impedance MeCaSUreMeNtS sistent iecckd iia edes haces he Aca hoses
14. Coefficient Plot Z and Y are complex number plots Vertical line cursor on all linear plots showing the frequency of the cursor The default HF mode Frequency Range of the data plots is from 1 to 150 MHz an alternative LF mode Frequency Range is from 8KHz to 1MHZ yes 8KHz Auto Scan and Manual Scan modes Adjustable Start amp Stop Frequencies Frequency Step and Dwell Time in mS to allow the line to settle out All parameters are saved on command for the next use Stores 500 data points with associated parameters for later PC Processing TBD Powered by six AA batteries and a 5V Switcher Power Supply You may use another power source LIPO if you want and feed the 5V switcher with that The DC DC switcher will accept an input of up to 36V DC Uses a TFT_320QVT display which is 320x240 pixels color and has a resistive touchscreen for parameter selection These are readily available on eBay Capable of Firmware download using USB cable from a computer Capability of moving stored data from the VIA to a computer for further processing Bill Sepulveda KSLN Ver 1 00 Page 4 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Theory of Operation The VIA consists of an RF generator a bridge circuit and a vector voltmeter The RF generator is two generators that produce two RF signals that differ in frequency by 2 kHz regardless of the frequency of the first generator A Si5351 chip from Silicon Lab
15. U6 is working We can move on to the next test in the sequence If there is 3 3 Volts on C1 and if there is no signal on R6 and R3 remove the VIA double and triple check the solder joints of U6 Si5351 and actually apply heat to each lead to allow the solder to reflow This one is tricky because of the small lead spacing and will be the second hardest parts to install and solder properly Put the VIA back together turn it on and recheck for voltage and signals If no signal remove the part and replace it with a new one Repeat all the steps above after installing the new U6 Si5351 If the screens come up quickly Jump up and down and have fun using the tool 3 Signal processing through U2 and U3 Now that we have signals emanating from U6 we need to check the signal coming from U6 to U2 and U3 There is a Resistive attenuator leveling network circuits between the output of U6 and input of U2 and U3 that needs to be checked Checking U2 functionality However we ll take a giant step and go right to the inputs of U2 and U1 first This will tell us if we have an issue somewhere in the leveling circuit of U2 and if U2 is having issues Remove the wires connected to U6 and connect as follows 1 Solder a wire to the side of C16 that goes to Pin 16 of U1 2 Solder a wire to the side of C21 that goes to Pin 1 of U2 3 Solder a wire to the side of C23 that goes to Pin 2 of U2 4 Solder another 8 inch length of small wire to
16. a new part may be required Repeat all the steps above after installing the new Oscillator U4 DSC1001 After the part has been replaced and the 12 MHZ signal is present but the screen still takes a long time to come up We now have to check other areas on the board If the screens come up quickly Jump up and down and have fun using the tool Bill Sepulveda KSLN Ver 1 00 Page 19 Type text AQRP Vector Impedance Analyzer Operations Manual Type text 2 Fo and Fo 2KHz Signal from U6 Check Now that the 12 MHz Oscillator is working let s check U6 for its Fo and Fo 2KHz signal Using the same small 8 inch wire 1 Solder one end of the wire to the side of R6 that connects to R5 Fo 2KHz signal 2 Add another 8 inch wire and solder it to the side of R3 that connects to R2 Fo signal 3 Add another 8 inch wire to the side of C1 where it attaches to L1 4 Mark the end of each wire for their respective test points Put the VIA back together and turn it on Using a DVM put the Negative lead to chassis ground and the Plus lead on the wire from C1 The meter should read a steady level 3 3 Volts Using a Scope connect the ground side of the probe to chassis ground and touch the probe end to the wire coming from R6 Adjust the scope to detect the signal Once the signal is detected connect the probe to the wire coming from R3 There should be very little change to adjust the signal If both of these signals are detected
17. at tool Remove the four test leads and enjoy However if the screen still comes up slowly check for a signal at C20 C22 C24 and C15 If all four leads show a signal than U3 is working Remove the test leads 3 Signal process through the Codec U1 Prior to removing the VIA to check components power up the VIA and move to the Tabular screen tap the Auto or Manual button on the VIA Setup screen and check the values in V1 V2 and IF Sig fields If there are values in these fields the codec is most likely working if not follow the process below Remove the VIA and recheck all the solder joints to U1 which is the hardest part to solder and most likely the one that is not soldered properly and will be the major problem and the hardest to fix So closely inspect all the solder joints to this part and make sure there is a good solder joint on all the pins and verify pin 1 placement on the board Check and re solder R7 R8 R9 R10 C6 C7 C8 C9 C10 C11 C12 C17 and C18 Verify the solder connections at pins 4 and 5 of the U1 These are the very important 12C control lines Bill Sepulveda KSLN Ver 1 00 Page 22 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Verify pin 4 of U6 CODEC SCL is connected to pin 6 of U5 and to the end of R9 that s connected to pin 9 of U1 Verify pin 5 of U6 CODEC SDA is connected to pin 5 of U5 and to the end of R10 that s connected to pin 10 of U1
18. cable to the VIA and then connect the other end of the cable to the computer The unit will be powered and turn on from the connection in the computer VIA Firmware Updates Next get the latest Firmware upgrade and copy it to a folder Go to http www gsl net k5bcq Kits Kits html site and scroll down the kit page until the section called PROGRAMMING RE PROGRAMMING Download the desired AQRP VIA HEX file Right click on the latest Firmware and click on Save Target as from the dropdown window The computer will ask what to do with the file Select a folder or create a new VIA Firmware folder and save the file into that folder When the computer comes up with the window at the bottom of the screen click on Open folder Go back to the STM32 ST Link Utility and click on File From the dropdown window click on Open File From the next window find where the firmware was saved select that folder click on the latest firmware file to highlight it and click on the Open button at the bottom of the screen This will open the file and set it ready to down load to the unit On the Utility program Tool Bar click on Target From the dropdown window click on Program amp Verify This will open a window to down load the firmware to the VIA Click on the OK button and watch the process window It will take about 20 second to down load and verify After the program is loaded see the information in th
19. e Z is the impedance toward the source and Z is the impedance toward the load Return loss is the negative of the magnitude of the reflection coefficient in dBs Since power is proportional to the square of the voltage return loss is given by RL dB 20 logy Z where the vertical bars indicate magnitude Thus a large positive return loss indicates the reflected power is small relative to the incident power which indicates good impedance match from source to load When the actual transmitted incident power and the reflected power are known i e through measurements and or calculations then the return loss in dB can be calculated as the difference between the incident power P in dBm and the reflected power P in dBm RL dB P dBm P dBm ReflCoeff Reflection Coefficient In physics and electrical engineering the reflection coefficient is a parameter that describes how much of an electromagnetic wave is reflected by an impedance discontinuity in the transmission medium It is equal to the ratio of the amplitude of the reflected wave to the incident wave with each expressed as phasors For example it is used in optics to calculate the amount of light that is reflected from a surface with a different index of refraction such as a glass surface or in an electrical transmission line to calculate how much of the electromagnetic wave is reflected by an impedance The reflection coefficient is closely related to the trans
20. e bottom of the window which defines what has been completed Close the Utility program and disconnect the VIA from the USB cable Turn on the VIA and notice in the Splash Screen for the new firmware update That s it now go and enjoy this great tool with its new firmware functionality Bill Sepulveda KSLN Ver 1 00 Page 26
21. e text AQRP Vector Impedance Analyzer Operations Manual Type text Section 4 Trouble Shooting Before starting on trouble shooting please be aware that it has been proven time and time again that 95 of the problems are due to solder problems opens shorts and miss registration of parts Splash Screen turn on timing issue If the Splash screen takes about 20 seconds to show up there is an issue in the VIA board that says the parts are not talking to each other The correct function of the tool is for the Splash screen to come up within two to three seconds after power is applied So what do we do Take the VIA board out of assembly and closely check every SMT part for a good solder joint It may be worthwhile to re solder every contact of all the parts to their respective pads and make sure all devices are installed properly Double check pin 1 orientation This can be checked by also using a DVM in the lowest Ohm setting and touching one lead to the pad and the other lead to the part that is to be soldered to that pad know it sound crazy but However this type of test will not work on the parts with their leads on the bottom of the part like U4 X1 and U1 If a connection is made between each pad and its respective component side then reassemble the unit and turn it on Pay close attention to the time it takes for the Splash Screen to start up If the Splash Screen comes up within two to three seconds that means all the parts
22. en See below e _ _ VIA Cal Connect ES Ohn Load This screen view is an example of the V1 03 Firmware 0 lt 2 f O e Please note the instruction on the top of the screen 1 Connect the 50 Ohm load to the antenna connection at the top of the unit Now tap the Cal 50 button A value should be displayed to the left of the lt 1 05 figure on the screen If the Screen shows nan please refer to the nan in the Cal setting in the trouble shooting section of this manual If the screen shows inf please check INF in the Cal setting in the trouble shooting section 2 The display at the top of the screen will change and ask to Connect 0 Ohm Load Remove the 50 Ohm load and install the shorted BNC connector Tap the Cal 0 button and another number should show up to the left of the lt 62 on the screen Again notice the instruction at the top of the screen asking to remove the O Ohm Load after the number has been displayed 3 After removing the load tap the CO Comp se button and a capacitance value should show V A Ca l Connect SB Ohn Load up below the other values Values should be something like what is CALSB 95 lt 1 020 lt 1 85 shown on the view to the right CALE 56 lt 68 681 lt 62 4 Tap the Done button and the data will be automatically saved The top of
23. er or tap the Minus button to decrease the number So let s set the start frequency to 007 000 000 than tap the Done button This will set the start frequency for the test and take the screen back to the VIA Setup screen Next tap the Stop_Freq button and set it to 007 300 000 and tap the Done button to go back to the VIA Setup screen Start Freq StopFreq Param Entry Param Entry Start Freq Hz Stop Freq Hz 007 000 000 007 300 000 e a ccna gt SS Next tap the Freq_Step button to set the steps to 000 001 000 and tap the Done button Now tap the Dwell_Time button to set the Dwell timing to 000 000 010 than tap the Done button If you wish you may tap the Store button on the VIA Setup screen to save this information so the next time the tool is turned on these parameters will be set automatically Bill Sepulveda KSLN Ver 1 00 Page 8 Type text AQRP Vector Impedance Analyzer Operations Manual Type text VIA Cal setup For this setup a50 Ohm resistor and a zero Ohm resistor are required Solder one side of the 50 Ohm resistor to the center pin of a BNC connector and the other to the ground or shield side of the connector This will work for the 50 ohm load and a shorted BNC connector will work for the O Ohm load Now tap the Cal button on the VIA Setup screen and the screen should change to show the VIA Cal scre
24. esign on audio baseband Q signals and process those for the required data This is done by using TWO synchronously tuned RF signals FO and FO 2 KHz one for the device under test and the other for the dual I Q mixers This has the unique advantage of being able to readily process negative complex numbers correctly which is a problem with many of the mid range commercial antenna analyzers in the market today After looking at several possibilities including the little NOKIA touchscreen it was decided to go for something far more usable and user friendly Here we have it The AQRP Vector Impedance Analyzer kit 25 It s a standalone battery powered Vector Impedance Analyzer for portable operation It can be used to check antennas filter designs etc which we will go into later in the manual This design will evolve over time as changes and improvements are made to function and visual presentation The STM board firmware is easily updated by using STM LINK software free and a USB cable So future firmware updates will be easy to do Bill Sepulveda KSLN Ver 1 00 Page 3 Type text AQRP Vector Impedance Analyzer Operations Manual Type text DESIGN FEATURES gt gt Measures V voltage amp Current Calculates Z Impedance in complex numbers Y Admittance in complex numbers k Reflection Coefficient RL Return Loss VSWR Voltage Standing Wave Ratio Plots Z Y k RL VSWR and Smith Chart Reflection
25. g to enter new parameters tapping START results in strange values on the display This can be because this is the first time the EEPROM U5 has been used and has no previously stored data This could also be due to problems communicating with the EEPROM U5 Check the solder connections to all of the pins on U5 and C4 If the Discovery board has not been updated with firmware V1 03 maybe updating the Discovery board with the latest firmware may help because it takes care of pre loading information into the EEPROM U5 when power is applied to the system See Firmware Updates on page 26 nan in the Cal setting This situation is not too bad It just means that before the Cal adjustment is made a set of frequencies need to be entered into the unit So start the unit and when it goes to the VIA Setup screen go and adda start and stop frequency See Frequency Setup on page 8 for setting the parameters This is a situation which may occur with older firmware version 1 02 and below This has been corrected in version 1 03 and above which preprograms a set of parameters into the tool on the initial startup inf in the Cal setting inf indicates that the VIA is not able to read the Load and there s something wrong in the resistor network Using an ohmmeter check the resistance from the center pin of the BNC connector to ground The meter should read 107 ohms plus or minus the meter calibration and resistor value
26. gnals now completely digital are each mixed with complex mixers to produce the and Q components of each of the two channels Conventional DSP techniques are used to further filter the four signals that now exist and to calculate the ratio of the amplitudes of the two IQ pairs and the phase difference between them At this point there is raw uncalibrated data The ratio and phase signals are now corrected to provide calibrated data The digital conversion of the two channels of 2 KHz analog signals and subsequent processing is what is referred to as a Vector Impedance Analyzer Allin all this is a rather conventional approach to impedance measurement but it has been chosen to capitalize on the design experience with microcontrollers and Software Defined Radio SDR to implement measurement computation plotting and display into a compact portable unit for field use all at a very reasonable cost Bill Sepulveda KSLN Ver 1 00 Page 5 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Let s Get Started BEFORE POWER ON there are a few things that should be done before applying power to the VIA 1 Make sure that the switching power supply is set for 5VDC 2 Before connecting the switching supply to the VIA use the ohmmeter to check the resistance from the 5V line on the VIA to a convenient ground connection on the VIA board This resistance check should be at least 100 ohms 3 Make sure the two pin co
27. ing transmission lines the source value is replaced with ZO the characteristic impedance of the transmission line Consequently Gamma ZL Z0 ZL Z0 Note that Gamma approaches 1 when ZL goes to zero In addition Gamma approaches 1 when ZL becomes very large VSWR VSWR Voltage Standing Wave Ratio is a measure of how efficiently radio frequency power is transmitted from a power source through a transmission line into a load for example from a power amplifier through a transmission line to an antenna In an ideal system 100 of the energy is transmitted This requires an exact match between the source impedance the characteristic impedance of the transmission line and all its connectors and the load s impedance The signal s AC voltage will be the same from end to end since it runs through without interference In real systems mismatched impedances cause some of the power to be reflected back toward the source like an echo Reflections cause destructive interference leading to peaks and valleys in the voltage at various times and distances along the line VSWR measures these voltage variances It is the ratio of the highest voltage anywhere along the transmission line to the lowest Since the voltage doesn t vary in an ideal system its VSWR is 1 0 or as commonly expressed 1 1 When reflections occur the voltages vary and VSWR is higher 1 2 or 1 2 1 for instance Bill Sepulveda KSLN Ver 1 00 Page 18 Typ
28. ll the test leads Checking U3 functionality Repeat the same test on U3 and its associated components 1 Solder one test lead to the side of C20 that goes to pin 6 of U3 2 Solder another lead to the side of C24 that goes to pin 1 of U3 3 Solder another lead to the side of C22 that goes to pin 2 of U3 4 Solder the forth test leads to the side of C15 that goes to pin 15 of U1 5 Solder another 8 inch length of small wire to the side of C25 that goes to Pin 8 of U3 6 Don t forget to mark the wires so you know who is who Before the unit is reassembled check the solder joints on all the pins on U3 and especially on Pin 4 of U3 You should now have 5 wires coming out of the unit for testing Check that there is a short between U3 Pin 4 and one side of C15 Again checking for a broken trace between the two points before the unit is reassembled Bill Sepulveda KSLN Ver 1 00 Page 21 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Put the VIA back together and turn it on Before checking for signals connect a DVM between chassis ground and the wire coming from C25 This wire should read 5 0 Volts If it does remove the DVM and check for signals at the other test leads If there is a signal at C20 C22 and C24 but no signal at C15 and all the solder joints are okay on U3 this means the attenuator leveling circuit is good to U3 However if there is no signals on either of C20 C22 or C24
29. lt HF frequency will be set HF Frequency 1 MHz to 150 MHz LF Frequency 8 KHz to 1 MHz When the Cursor Control knob top knob is pushed down to engage the switch while applying power the unit will set the frequency range from 8 KHZ to 1 MHZ When applying this function the Control must be held down until the VIA Setup screen is visible When the Manuel Control knob is pushed down to engage the switch while applying power the unit will reset the Start and Stop Frequencies to their initial default values of 1MHZ and 30MHz respectively Remember to hold the Control down until the VIA Setup screen is visible Typical values for V1 V2 and IF_Sig The following table shows values that are typical when the start frequency is set for 3 MHz and with various loads This is good information to better understand the readings in the Plot screen prior to creating a chart Load V1 V2 IF Sig OPEN 3900 60 16000 50 Ohm 3200 3200 9200 0 Ohm 2800 4700 7000 Component variations may change these values but their relative magnitudes should be consistent for the various load conditions Note particularly that V1 will be much larger than V2 with an open load V1 and V2 will be nearly equal with a 50 ohm load With a0 Ohm load SHORT V2 will be larger than V1 In addition IF Sig will be largest with an open circuit load and will drop as the load resistance approaches 0 ohms Bill Sepulveda KSLN Ver 1 00 Page 15 Type text AQRP Vector Impedance
30. mission coefficient The reflectance of a system is also sometimes called a reflection coefficient A wave experiences partial transmittance and partial reflectance when the medium through which it travels suddenly changes The reflection coefficient determines the ratio of the reflected wave amplitude to the incident wave amplitude Bill Sepulveda KSLN Ver 1 00 Page 17 Type text AQRP Vector Impedance Analyzer Operations Manual Type text A signal travelling along an electrical transmission line will be partly or wholly reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line or if the far end of the line is not terminated in its characteristic impedance This can happen for instance if two lengths of dissimilar transmission lines are joined together Reflections cause several undesirable effects including modifying frequency responses causing overload power in transmitters and overvoltage s on power lines However the reflection phenomenon can also be made use of in such devices as stubs and impedance transformers The special cases of open circuit and short circuit lines are of particular relevance to stubs Reflections cause standing waves to be set up on the line Conversely standing waves are an indication that reflections are present There is a relationship between the measures of reflection coefficient and standing wave ratio In discuss
31. mum frequency of the device being tested which should also approximately correspond to the lowest VSWR frequency measurement However this may not always be true e g if the VIA is being used to check a very narrow band antenna such as a high Q magnetic loop Left example is a VSWR graph Note the sharp tuning Right example is an Impedance graph Note where the two plot lines cross their Two Element Mag Loop 0 line Bill Sepulveda KSLN Ver 1 00 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Admittance To create an Admittance profile select Admittance as the last step Tabular screen e 7 109 687 Hz Admittance Again we have two scales to compare however in this case no matter at what frequency the Cursor Control is at really doesn t matter because both the White and Green line are pretty flat See the definition for Admittance for more details on this graph ReturnLoss To create a Return Loss profile select ReturnLoss as the last step Tabular screen 7 678 312 Wz Retura Less In this test there is only one scale and rotating the Cursor Control to the lowest location on the graph will identify the frequency of the lowest reading on the plot Again this should be close to the lowest VSWR measurement frequency See the definition for Return Loss for more details on this graph ReflCoeff Coax Testing To create a Reflection Coefficient p
32. nd apply power and repeat the measurements as stated previously If a signal is detected on C21 C23 and C19 it means the filter circuit is now working However if there is no signal on C16 it means U2 may still have issues Remove the VIA and double check the solder joints on all the pins of U2 and especially on Pin 4 of U2 Re solder both sides of C15 to make sure it is making a good connection Before the unit is reassembled check that there is a short between Pin 4 of U2 and one side of C16 Just checking for a broken trace between the two points before the unit is reassembled Again use the DVM to ensure the signal path between the parts is good This check is making sure there is a path for the signal to get from U2 to pin 16 of U1 Put the VIA back together and turn it on Now check for signals at all test leads If there is a signal at C19 C21 and C23 but still no signal at C16 and all the solder joints are okay on U2 this means U2 is bad and needs to be replaced After replacing U2 and reattaching the five test leads put the VIA back together and turn it on Pay close attention to the screen timing If the screen comes up quickly then you re finished trouble shooting and can now Start enjoying the use of this great tool Remove the five test leads and enjoy However if the screen still comes up slowly check for a signal at C19 C21 C23 and C16 If all four leads show a signal than U2 is working Remove a
33. nnector that supplies power to the VIA is oriented correctly Mark one side of the board and connector to insure proper orientation when connected These checks are to minimize the risk of releasing the magic smoke when the VIA is first powered on After the items above have been verified and the unit has been assembled turn on the power The Splash Screen should come up within two to three seconds after the power has been applied It will display the date and time of the latest version firmware See below Screen Calibration When the unit is turned on for the first time the unit will immediately go from the Splash screen to the Calibration screen See below Follow the instructions on the screen and when instructed tap the screen three times in quick succession to save the touch screen calibration Bill Sepulveda KSLN Ver 1 00 Page 6 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Now turn the power off and back on Like mentioned before the Splash screen should show up after about two to three seconds and after the Splash screen is displayed for a few seconds the VIA Setup screen should be displayed Allis good YEA ECION Lil DaAMct arm Yri Okay here s where the fun starts and where the rubber meets the road But it depends on the mannerism of the person who spent all this time building the VIA and if the unit doesn t startup as stated If the unit
34. od there could be a problem with the setup of the U6 due to a failure to set the start and stop frequencies The following paragraphs describe how to check signals through the PCB to the U1 codec If an oscilloscope is available check for a square wave signal at the junction of R1 and R2 Also check for a square wave signal at the junction of R4 and R5 These are the two outputs of the U6 Each should have an amplitude level of about 1 5 volts peak peak pk pk If either signal is not present check the connections to U6 again as well as the connections to C2 and C3 If both outputs are missing make sure that crystal X1 is properly soldered If these checks are OK check the outputs of the two attenuators The signal at the junction of R2 and R3 should be about 300 millivolts pk pk The signal at the junction of R5 and R6 should be about 100 millivolts pk pk Check the solder connections again if either signal is missing If the levels are incorrect check the resistor values R1 to R6 Now check the signals at the junction of R11 R12 R14 and R15 This should be the same as at the junction of R2 and R3 Next check the signal at the junction of C19 and C20 This signal should be the same as the junction of R5 and R6 The same signal should be present at pin 6 of each of the SA612s U2 and U3 This completes verification of the local oscillator going into the mixers and the excitation to the bridge Finally check continuity from pin 4 of U2
35. of the manual Test performed by the VIA SmithChart Smith Chart Impedance Impedance Admittance Admittance ReturnLoss Return Loss ReflCoeff Reflection coefficient VSWR Voltage Standing Wave Ratio The VSWR test for the 40 meter antenna is the next step So tap the VSWR button and watch the show as the chart is drawn on the screen as we Speak Bill Sepulveda KSLN Ver 1 00 Page 10 Type text AQRP Vector Impedance Analyzer Operations Manual Type text If the antenna s in range it should look something like the views below The antenna in the views below is set to the CW end of the Band and at the low end of the phone band as indicated by the line using the Cursor Control The location of the defined function knobs may vary based on the individuals positioning of the controls The Cursor Control is used to move the vertical line on the screen to identify the frequency at the lowest indication on the curve or lowest VSWR in this example Low end of the CW band section Frequency of Lowest VSWR VSWR at the low end of the Phone band SS re E LILET 108 7 002 812 Hz USWA 7 068 937 Hz USWR 7 168 312 Hz USWR VSWR Measurement using the Manual Plot Mode In the VIA Setup screen there is also a Manual button When this button is selected it requires the use of the Manual Control knob to plot the chart manually instead of automatically The processes are the same as the
36. older any suspicious area Use an ohmmeter on the lowest resistance setting to check the points mentioned above If the reading indicates a short re solder the leads or component to remove the excess solder and inspect the part very closely Re solder ALL the pins of U1 and again check for a short on the 3 3V line by connecting the negative lead of the ohmmeter to ground and touching the positive lead to Pin 5 amp 6 of J2 on the VIA board If a short is still indicated there is most likely a glob of solder under U1 creating the problem Remove U1 and remove the excess solder to any pins of U1 Re install U1 and re check for the short test on the pins of J2 If no short is indicated re install the boards to the stack connect the power connector the VIA board and apply power to the unit Re check the 3 3V line on P2 for any variations Also check to see if the Splash and Bill Sepulveda KSLN Ver 1 00 Page 23 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Calibration screens came up If screens are now working continue with the instructions on page 6 and go through the initial setup Don t forget to reconnect the wires to the BNC connector However if nothing happened it might just be U1 got fried and needs to be replaced After replacing U1 re check for the short test on the pins of J2 for a short in the 3 3V line If good re assemble and have fun Start Stop Step Dwell not being saved When tryin
37. rofile select ReflCoeff as the last step Bill Sepulveda KSLN Ver 1 00 Page 13 Type text AQRP Vector Impedance Analyzer Operations Manual Type text 50 Ohm Terminated 25 Ft RG 8X Open ended 25 Ft RG 8X Shored end of a 25 Ft of RG 8X This is the test to check the condition of a length of coax with the end of the coax terminated with 50 Ohms Open Ended coax and with a short at the end of the coax For more details on the explanation of the Reflection Coefficient please see the Technical Definition section Also the photos used in this example were made with a relatively narrow frequency range Generally coax testing is done over a wide range of frequencies where the length may be one or more quarter wavelengths and the plots will show much greater variation Another example Below are graphs of a piece of RG 8A coax 66 feet long and made for a 40 meter wave length feed line to feed a 40 meter coaxial antenna The coax was rolled up into a about a 15 inch diameter loop when the measurement was taken Note the waveforms for an Open Output and Shorted Output should be the same when measured directly at the VIA coax connector Wave on 40 W 50 Ohm load Wave on 40 Open Ended Wave on 40 W Shorted End Bill Sepulveda KSLN Ver 1 00 Page 14 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Other Functions Encoder Knob functions Anytime the unit is turned on without Encoder action the defau
38. s e Sisthe susceptance measured in Siemens Bill Sepulveda KSLN Ver 1 00 Page 16 Type text AQRP Vector Impedance Analyzer Operations Manual Type text ReturnLoss In telecommunications return loss is the loss of power in the signal returned reflected by a discontinuity in a transmission line or optical fiber This discontinuity can be a mismatch with the terminating load or with a device inserted in the line It is usually expressed as a ratio in decibels dB RL AB 10 logy 5 r where RL dB is the return loss in dB P is the incident power and P is the reflected power Return loss is related to both standing wave ratio SWR and reflection coefficient f Increasing return loss corresponds to lower SWR Return loss is a measure of how well devices or lines are matched A match is good if the return loss is high A high return loss is desirable and results in a lower insertion loss Return loss is used in modern practice in preference to SWR because it has better resolution for small values of reflected wave Electrical In metallic conductor systems reflections of a signal traveling down a conductor can occur at a discontinuity or impedance mismatch The ratio of the amplitude of the reflected wave V to the amplitude of the incident wave V is known as the reflection coefficient l i Pi T r Vi When the source and load impedances are known values the reflection coefficient is given by Z a L Za wher
39. s in the circuit If the reading is close to this value the resistors values are correct and solder joints are good The problem may be in the Load resistor or solder joint at the BNC Or resistors may need to be checked for their value and proper solder joints Please check the schematic for detail values Here are some hints for different resistance readings Measurement Component Inf R14 and or R16 open 115 ohms R1 and or R2 open 146 ohms R3 open 123 ohms R12 and or R13 open Tabular Screen issues This is a situation where the Parameters have not been programmed into the Start and Stop Frequencies See Frequency Setup on page 8 for setting the parameters If the system is not up to V1 03 firmware see the Firmware Updates section This update pre programs information in the EEPROM so the first time a Plot screen is brought up the data is read from the EEPROM to help set up the different fields If there s still an issue with the correct readings for V1 V2 and IF_Sig then try the following Bill Sepulveda KSLN Ver 1 00 Page 24 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Very low readings for V1 V2 and IF_Sig This is usually due to a low or no signal being passed to the codec U1 The problem may be due to a non functioning U6 or a problem in the signal path from the U6 to the codec U1 Chances are there is a solder problem In addition if the connections are all go
40. s is used for this dual generator The bridge circuit produces two output voltages one is proportional to the voltage applied to the load impedance and an additional resistor and the other is proportional to the current flowing through the load impedance The resistor in series with the load limits the current in the load if it s a short circuit Consequently the ratio of the amplitudes of the two voltages and the phase difference between them provide enough information to accurately determine the load impedance plus the added series resistance From the calculated load impedance Impedance the complex reflection coefficient ReflCoeff and other parameters of interest may be determined However the raw measurements must be corrected for inaccuracies in the values used in the computations This is accomplished in the calibration procedure Since the bridge produces two voltages with some phase difference between them experience in using IQ signal processing to make the computations has been applied to the design In particular each of the voltage outputs is split into In phase and Quadrature IQ components This is done after each signal is mixed with a local oscillator the RF signal that is offset by 2 KHz from the RF excitation of the bridge The two audio signals thus generated are then digitized with a 16 bit A D converter and sent to the STM32 microcontroller Each signal is filtered with a 2 KHz band pass filter The filtered si
41. the side of C19 that goes to Pin 6 of U2 5 Solder another 8 inch length of small wire to the side of C26 that goes to Pin 8 of U2 6 Don t forget to mark the wires so you know who is who The accomplishment of this test is to find out if there is a signal going from U6 to the inputs of U2 and from the output of U2 to U1 It also checks if there is power getting to U2 Reassemble the unit and apply power Before checking for signals connect a DVM between chassis ground and the wire coming from C26 This wire should read 5 0 Volts If it does remove the DVM and connect the Bill Sepulveda KSLN Ver 1 00 Page 20 Type text AQRP Vector Impedance Analyzer Operations Manual Type text scope probe to the small wire connected to C21 and adjust the scope for a signal If a signal is detected move the scope probe to the small wire connected to C23 If a signal is detected move the scope probe to the wire from C19 and adjust the scope to detect a signal Than move the scope probe to the lead connected to C16 If a signal is detected on C21 C23 and C19 it means the attenuator leveling circuit is working However if there is no signals C21 or C23 or C19 that means there is a bad solder joint in one or more of the attenuator leveling components Remove the VIA and re solder C19 C21 R11 R14 and C23 and make sure there is a connection between C23 and Pin 2 and C21 and Pin 1 of U2 This can be checked by using a DVM Reassemble the unit a
42. to the end of C16 that is opposite the end that is connected to pin 16 of U1 Also check continuity from pin 4 of U3 to the end of C15 that is opposite the end that is connected to pin 15 of U1 If all else check OK make sure that U4 is properly soldered If the available oscilloscope is capable of displaying a 25 MHz signal check for this signal at both ends of R7 At this point assuming that there are no damaged components V1 V2 and IF Sig should be close to the values shown in the note below Encoder Reverse wiring Function ENC 2 ENC 1 eA LA G Groaund 2E 1B ePE IPE f the Encoder works in reverse just Flip the A and E leads Bill Sepulveda KSLN Ver 1 00 Page 25 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Section 5 Firmware updates STM32 Utility link Download the STSW LINKO04 STM32 ST LINK utility Click on the link or enter this link into the search a computer search program http www st com web en catalog tools PF258168 After clicking on the link a web page will open for the STSW LINK0O04 SSTM32 ST LINK utility Scroll down the Download page to where it show the Download button Download Click on the Download button and follow the installation instructions Once the file is installed it will put a short cut Icon on the Desk Top Click on the Icon to open the file STM32 ST link Utility This sets up the utility to update the latest firmware on the VIA Connect a USB
43. up screen Bill Sepulveda KSLN Ver 1 00 Page 7 Type text AQRP Vector Impedance Analyzer Operations Manual Type text Frequency Setup Okay now that the screens are doing what they should let s go setup the frequencies Prior to setting the Cal function it is necessary to enter some values into the different field on the VIA Setup screen On the left side of the VIA Setup screen there are four buttons which will be programmed now for a 40 meter test example later These are used to set the VIA parameters for measurements and which to some may seem intuitive however we ll explain their usage anyway Start_Freq button is used to set the Starting Frequency of what is to be tested Stop_Freq button is used to set the Stop Frequency of what is to be tested Freq_step button is used to set the Frequency Steps at which the chart will be drawn Dwell_Time button is used to set the speed at which the chart is to be drawn Screen buttons may be activated by tapping the buttons with the index finger or by using a retracted ball point pen as the pointing device to activate the button For the 40 meter test example tap the START_FREQ button In the next screen set the frequency to 7 MHz on the display Tapping the Start button for the first time will display a frequency of 001 000 000 The display contains a Plus and Minus button under each number Just tap the Plus button to increase the numb
Download Pdf Manuals
Related Search