All about commercial and home-build measurement devices
I was able to get a used 40dB power attenuator from a fellow ham. It is a 250W version in a very good condition. The attenuator should be usable up to 6GHz.
Ich habe von **** eine gebrauchte, schaltbare Eichleitung gekauft. Laut Aufschrift stammt sie von **RE Instruments** aus Jülich. Sie dürfe aus der Zeit vor der Jahrtausendwende stammen und ist wohl aus einem HF-Signalgenerator ausgebaut worden.
In this post I describe in details, how you can create the calibration factors for k0 ... k3 based on raw data measured with the power sensor.
With the firmware version 1.9.0 there are some minor enhancements:
- Peak-hold works now, when offset is set
- Meter and diagram works in dBm and W mode
Here are the required files:
Some times ago, I found for me a solution, how to handle the unstable readings from the ADC. I've described it in this post.
In the meantime, some HAMs also build the RF powermeter based on the work of Makis, SV1AFN and myself. One if these HAMs, PA3AXA Rens, digged a little bit deeper and analysed the problem in detail. Here his description.
With the firmware version 1.8.1 there are some minor enhancements:
- Offset value is displayed on main screen. "O" at the end of the unit is removed
- Waveform display also correct when offset is enabled
Here are the required files:
The Nextion display needs the content defined in the file PowerMeter.HMI. You can either upload it with the Nextion editor via a serial link to the display or you can copy the TFT file to an SD card and put this into the socket on the Nextion display.
If you are using my powermeter software in conjunction with Maki's module and have a unstable readings or sporadic extrem value changes, this is a problem of the CS pin. It may be a grounding issue - Makis is currently analysing the problem.
I've developed a new firmware for my RF Powermeter. In this firmware, the user can now program for six calibration points the factors for the polynimial regression functions.
Therefor I've developed a JAVA GUI application for downloading these floating point values to the device.
*** CAUTION ***
All stuff described in this post is ONLY running on an Arduino which runs the OptiBoot bootloader. The EEPROM capability of the OptiBoot bootloader is needed for the features of firmware V1.7.1
The original library from Dan is not working as expected for me. So I adopted the code a little bit.
You can find the changes below. You can also download "my version" of the library here. Unzip into the Arduino's library folder.
To have a stable 10MHz reference in my shack, I've ordered a SYMMETRICOM based GPSDO from an Chinese eBay seller. It was delivered in kit form, so no issues with missing CE marking etc.
The GPSDO is build into a sturdy aluminium case with a PCB front panel and an aluminium back panel.
To get into the story I recommend to read the following articles in this sequence:
- RF Powermeter - First steps
- RF Powermeter - Uploading HMI file
- RF Powermeter - Firmware 1.8.1
- RF Powermeter - Precision
- RF Powermeter - Calibration basics
- RF Powermeter - Unstable readings
- RF Powermeter - Unstable reading - Reloaded
- RF Powermeter - Updated display files