VU3SQM directional wattmeter build – #1 laid out the first steps in design review and build of a directional wattmeter. This article canvasses the issues of the display. Intention is a digital based display (though not to exclude an analogue meter or bar graph type displays). So, the output of the AD8307 needs to be … Continue reading VU3SQM directional wattmeter build – #2
VU3SQM offers an interesting directional coupler based on a Sontheimer coupler, and using AD8307 power sensing for a nominally HF coupler. I must say that I am not a fan of Sontheimer couplers… but that is what the board uses. This article lays out a preliminary design review to assist in selection of appropriate toroids, … Continue reading VU3SQM directional wattmeter build – #1
The RF Power Meter 2 (RFPM2) stores calibration constants in a file located in the (SPIFFS) file system in the microcontroller flash. The file opened by default when RFPM2 starts is /default.cfg, the following is an example. { “name”:”dBm”, “hostname”:”rfpm201″, “vref”:3.3, “avg”:3, “slope”:0.12991, “intercept”:-91.406, “unit”:”dBm”, “lcdfsd”:16 } The parameters above capture the most basic operation … Continue reading RFPM2 – calibration files
The RF Power Meter 2 (RFPM2) stores calibration constants in a file located in the (SPIFFS) file system in the microcontroller flash. The WiFi credentials are stored separately at the default location in the flash. Calibration constants The AD8307 outputs a voltage from zero to about 3V for inputs from around -90 to +15dBm. The … Continue reading RFPM2 – calibration
The RF Power Meter 2 is a development based on the utility of RFPM1, but it shares nothing with the RFPM1, save using an AD8307 as the sense module. Design criteria The design criteria are: small, portable, battery powered; direct reading dB scale; flexibility for a range of adapters to measure power, current etc; local … Continue reading RF Power Meter 2 (RFPM2)
At Time to get some experience with 32bit microcontrollers I wrote that after almost 50 years working with 8bit microcomputers and microcontrollers, I thought it about time to get my hands dirty on some 32bit microcontrollers. This article reports some work in the STM stream. I abondoned the ST Discovery board in favour of a … Continue reading Time to get some experience with 32bit microcontrollers – some progress
My recent article Near-field field strength measurements using the RFPM1 described a technique using VK3AQZ’s RF Power Meter which is based on the AD8307 log detector. There are many ways to measure low level RF power or voltage, and this article describes methods that I have used using a simple diode detector attached to the … Continue reading Near-field field strength measurements using a diode detector
This article documents my build of Lou Destefano’s (VK3AQZ) RF Power Meter kit. The power meter is based on probes using an AD8307 logarithmic detector. Above, the RF Power meter with two probes. (The ferrite sleeves were not part of the kit.) Last update: 9th December, 2014, 8:39 AM