RF Power Meter 2 is a logging RF power meter based on AD8307 and ESP8266.
This article describes its calibration and use with a 40dB 50Ω 20W attenuator to make a 20W or 43dBm RF power meter.
Above is a pic of the system under test on a nominal 5W transmitter, indicating 37.4dBm, equivalent to 5.5W. Continue reading RF Power Meter 2 (RFPM2) – 40dB external attenuator calibration and integration
Over the last few years I have evaluated many of the competing firmwares for the NanoVNA, and needed a method to quickly and reliably write new firmware to the device. Continue reading NanoVNA-H* – my method for firmware updates
I noted some online discussions where some people had troubles with the displayed forward and reverse RF power values, and the calculated SWR.
Some of the reports indicate non-zero RF power values displayed when the transmitter is off, symptoms which direct diagnosis in the first instance to review of the ADC input circuit.
This article reviews the hardware design based on documents as published at the date of this article.
Let’s start by reviewing some relevant parts of the AtMega328P datasheet.
Above is a simplified schematic of the ADC pin input circuit. Note the current sources IIH and IIL. Continue reading (tr)uSDX – review of the directional coupler ADC design