FA-VA 4 / FA-VA 5 Antenna Analyzer

Today the FA-VA 4 und FA-VA 5 antenna analyzers are frequently used by hamradio operators and other users.

A description of the FA-VA 5 and its usage with the VNWA software in English and Danish language can be found in the download section.

On the Hamradio 2018 in Freidrichshafen there was a workshop about networkanalyzers, but also a presentation in English language about the FA-VA 4 and FA-VA 5.
Decks are available in the download section.
Link to the videos on Youtube:
German: https://www.youtube.com/watch?v=ryazPDSNDLU
English: https://www.youtube.com/watch?v=X8Z7veGV57o

Please note that SDR-Kits is also selling very usefull accessories like a presentation case and different adapters.


Local parameters for BNC-Calibration-Set (BX-245-SOL / SDR-Kits)
Q: The attached note shows different sets of parameters. Which one should be used?
A: The calibration-set is a male one, therefore the first set of parameters should be used (male, simple model).

Local parameter port-delay/ps
Q: What does port-delay mean? I do not find this parameter on the attached note?
A: Port-delay has nothing to do with the calibration set. Port-delay enables a shift of the measurement plane in total. For further information, please have a look at the VNWA help document. If not used, it should stay at 0.

Calibration file for BNC-Calibration-Set (BX-245-SOL / SDR-Kits)
Q: If I load the parameter file by the link from the attached note, will the parameters be transferred also to local setting in the FA-VA 5?
A: No, because of software architecture this is not possible. Local parameters (without VNWA) have to be entered in addition locally manually into the FA-VA 5

Change of center frequency for sweeps
Q: Changing the center frequency for sweeps takes some time, if there is a change from one band to the other. Is there any other way to do this faster?
A: Yes, the frequency may be set in any single frequency measurement mode. This will be very fast as every single digit can be changed separately. Switching to sweep modes the frequency will be transferred as the center frequency.

Change requests for a new firmware version
Q: How do I best address change requests for a new firmware version?
A: Best is to send an e-mail to dg5mk@darc.de. But before sending, please check here if the requests is not already on the list.

Command interface to control FA-VA 5 via serial interface
Q: I would like to use the FA-VA 5 for my own software. Is there an overview about the serial command interface?
A: The USB-interface will show up as a serial COM-Port at the PC. Parameters are 8,N,1 and 115200 Baud. The interface may be tested with a terminal program like HTERM. CRLF has to follow each command. Please no questions like 'What should I do with this?' If you don't know how to handle this please use the VNWA software. Evaluation of uncalibrated s11 reflection coefficients (and the calibration itself) is very challenging!

//USB/UART interface description; all orders and replies will be handled as ASCII lines; the following orders are implemented

//'IVSCN start_f stop_f #samples opt1 opt2'
//except first part as string all values have to be integer
//opt1 = 0 means fast scan, opt1 = 1 means standard scan, opt1 = 2 precize scan
//opt2 means add delay time between samples in Milliseconds
//reply is Touchstone header and #lines as #requested samples as uncalibrated s11 values from Bridge-Head
//if #samples = 1 f_stop will be ignored

//'IVRAG' - range
//replies fmin fmax both as integer

//'IVIDF' - identify
//replies line 'DG5MK Antenna Analyzer Vx.y firmware Va.b'; continues sweep afterwards

//'IVINI' - initialize
//replies'OK', waits for new command

//'IVRST' - restore
//replies'OK', waits for new command

//'IVSTP' - stop
//replies'OK', waits for new command

//'IVLDS' - list data sets
//replies string with timestamp per line for each dataset (16), waits for new command

//'IVRDS nbr' - read data set #n
//number has to be integer, 0 to 15 for 16 available datasets a 100 samples
//reply is Touchstone comment line with timestamp, header line and 100 lines for frequency, s11 real and s11 imag, calibrated and ready to plot


Current firmware: V1.09


firmware version 1.09 from 05/03/2019

changes from version 1.08 to version 1.09
1) new mode LCR-Meter to make it easier to measure components. Included quality measurement (Q) requires careful calibration.
2) saving of five presets included. Works like screen and dataset saving and does include all current parameters.
3) new battery low message at startup, if battery is below 2.5 Volts.
4) SWR sweep scale aligned to 5 frequency and single frequency scale, now lines at SWR 1, 1.5, 2, 3, 4, 6, 10.
5) backlight ON if powered from USB, will move to old mode if powered from battery.
6) improved program flow, mainly in single frequency measurement, to better react on press of button.
7) all delay calibration settings now with 1/100 resultion at display (internally double/ long double processing).
8) several bug fixes and other small improvements.

Current firmware: V1.08 - accepted change requests - next version scheduled for end of Q1 / begin of Q2

1) 11/04/2018 - backlight - force display backlight to 'fully on' if USB cabel is plugged in; allow configuration 'fully on' vs. 'traditional mode like DIM, Auto etc' in setup menu
2) 11/04/2018 - buzzer - buzzer does not restart automatically after pulling out USB-cabel and moving to SWR-buzzer mode. On/Off or manual selection 'SWR-buzzer' needed
3) 11/22/2018 - swr scaling - change plot scaling for SWR sweep analog to 5 band view to 1, 1.5, 2, 3, 4, 6, 10 (t.b.c)
4) 11/22/2018 - backlight - backlight in auto-mode should stay on as long as a button is pressed
5) 11/22/2018 - frequency change speed - press and hold a button to change frequency should be a stepped approach, from slow to fast during pressed button
6) 01/26/2019 - presets - individuel sweep presets (center frequency, range, mode)


Current firmware: V1.08

firmware version 1.08 from 09/26/2018

changes from version 1.07 to version 1.08
1) frequency span will be saved in EEPROM during power off / on
2) wrap around (up and down) for menus with more than 4 items implemented
3) 'auto SWR' implemented (new menu item 'Auto SWR' in setup menu, default is 'off'); this includes jump of marker to minimum SWR after SWR-sweep and transfer of marker frequency as frequency of single-frequency-SWR measurement; this allows quick SWR checks from sweep to detailled analysis
4) SOL entries moved to last items in single- and multi-frequency measurement menus
5) new increase / decrease scheme for span of multi-frequency-modes with 10, 20, 50 kHz etc. implemented; (new menu item 'Span Start' in setup menu, default is 'Start 100 kHz'); the old scheme (multiple of 2) can be enabled via the new menu
6) some smaller bug fixes in display routines and rework of interrupt processing to prevent issues because of peripherals timing


Current firmware: V1.07 - accepted change requests

1) 06/18/2018 - menu - allow wrap around scrolling in menus
2) 06/21/2018 - Z display in sweeps - very small real parts of impedances may become negative. This will lead to 'out of range' display which leads to jumps in the trace. Better plot negative values instead showing them 'out of range'
3) 07/10/2018 - menu - swap entries for SOL and according measurement; first the measurement, second the SOL
4) 07/10/2018 - frequency span sweeps - the last defined frequency span should be saved and not fall back to default if mode is changed
5) 07/10/2018 - transfer frequency of marker from sweep - moving from sweep measurement to single frequency measurement the marker frequency should become the new measurement frequency, not the middle frequency (t.b.c)
6) 07/15/2018 - frequency span sweeps - give user a choice in setup to have span as a power of 2 kHz (2, 4, 8, 16 ...) or multiple of hundreds kHz (50, 100, 200, 400, 800) (t.b.c)
7) 09/09/2018 - marker to minimum SWR - automatically move marker to minimum of SWR after sweep (on/off to be selected in setup)