BG7TBL FA-5-6GP Frequency Counter inside and some tests - Page 1
Forum section: electronics / testgear

author: KedasProbe
author_rank: Frequent Contributor
timestamp: August 09, 2024, 08:44:41 am
content: Hi,Some PCB pictures for those that are interested,PCB board is year 10/2021 and firmware 6/2024Gate-time maximum is 20sec, above it it waits that long but gives wrong data.Serial commands in the zip file.I wrote a program for it since there is no screen on it, if it's not easy to read it's annoying to me anyway, so I decided I can use the one without screen and write a program for it.It's based on an existing general serial communication program.https://github.com/mcagriaksoy/Serial-Communication-GUI-Program(Note: I wanted to add some time graphs but I couldn't get it to work, library compatibility....)EDIT:- There is no power switch but the PCB board does have a connector for it, if you remove the solder join on the connector pins, at the front left from the led there is some room for a hole.- I updated excel file so the graphs load fasteroffset is changing with gate-time but also with freq it seems (see offset dip 10Mhz at 1sec and 100Mhz at 0.1sec).- serial communication is a bit tricky since you have to wait until the measurement is done before it does something and it only remembers the last command given, this can feel like it doesn't work at long gate-times.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: August 24, 2024, 07:32:02 pm
content: Some extra info to reflect on:Input impedance of CH1 is around 50\$\Omega\$ but for CH2 it's around 32\$\Omega\$Source code of my program:https://github.com/Ken26M/FA-5-6GP_MonitorControlIt can store all measurements with a timestamp, the statistics are also added to a csv file when you copy to clipboard.Even if you use the timelab program to record you can change the settings with this program and thenpress disconnect and connect with timelab.edit:The program does not use floats (64bit) for the long frequency numbers but decimals.If you want to use it for an other device like FA-2 or FA-3 you will need to change the parsing code in fa5usbdata.py, function 'add_string' and probably also the lineif serial_data == "$"in ui_main.py that decides in which textbox the text line must be displayed.You may need to install a driverhttps://ftdichip.com/Drivers/vcp-drivers/if you see only a USB device and not a com port.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: October 14, 2024, 04:55:55 am
content: seem same as fa-2 / 3 ; but no displaybtw, the correction voltage for VECTRON , from tl431 , it connected to input 12v , over regular resistor, and very sensitive to input 12v voltageso ideally need very stable 12v input or redesign correction voltage source; or something ext stable FrefTL431 itself quite drifty over time.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: October 19, 2024, 05:15:38 pm
content: I did some measurements and it doesnotseem to be very power supply sensitive.I only see about -0.3 PPB/V around 12VIf you change the power supply voltage with 1 volt you have to give it a minute to settle down again (see step response graph)I also included the warm up time that is long, about -8mHz/hour or -0.8PPB/hour, 1 hour after power on.You should at least wait 2 minutes before using it but that is normal for an OCXO.All measurements were done with a gate time of 2sec and a GPSDO 10MHz source signal to measure.P.S. I didn't add a power switch on the device to avoid adding holes, I added an external switch on the 12V line.

author: Kurt_!
author_rank: Regular Contributor
timestamp: October 15, 2025, 08:25:14 pm
content: I discovered this program and wanted to try it out (FA-3).Unfortunately, it won't start. What am I doing wrong? Unfortunately, I'm not familiar with Python programming.But maybe someone can help me...