Chinese AD8307 power measurement module #4

Desk study of opportunity to improve linearity. At Chinese AD8307 power measurement module #2 I showed measurement of the linearity of an AD8307 based RF power meter. The specification linearity is +/-1dB, which is poorer than one might like in a power measuring instrument. The diagram above from the AD8307 datasheet shows the internal architecture, including … Continue reading Chinese AD8307 power measurement module #4

Chinese AD8307 power measurement module #3

At Chinese AD8307 power measurement module #2 I concluded that the modified AD8307 was useful on HF, and through to 54MHz depending on accuracy requirements. This article looks at combining the AD8307 module with a display option based on an Arduino Nano. Above is a demonstration of the display prototype. The module in the foreground … Continue reading Chinese AD8307 power measurement module #3

Chinese AD8307 power measurement module #2

At Chinese AD8307 power measurement module #1 I documented the first phase of checkout of a low cost AD8307 module. There are two requirements for accurate power measurement: input impedance of the power meter must be very close to 50+j0Ω (say input VSWR<1.2); and then gain from the SMA terminals to the AD8307 input terminals … Continue reading Chinese AD8307 power measurement module #2

A magnetics review of the VK3AMP Sontheimer directional coupler

This article documents a review of the magnetics of the ‘voltage’ transformer in the VK3AMP Sontheimer directional coupler. It is typically the most important component in determining InsertionVSWR and ReturnLoss at the lowest frequencies. The transformer of interest is the one to the left, and if you follow the tracks, the multiturn winding is connected … Continue reading A magnetics review of the VK3AMP Sontheimer directional coupler

Basic measurements of the VK3AMP Sontheimer directional coupler for a N2PK wattmeter

This article documents measurement and analysis of a VK3AMP Sontheimer directional coupler in an implementation of a 400W wattmeter design by N2PK (Kiciack nd). I purchased one of the couplers for use with a DIY digital display, and although I have had it longer, it isn’t yet realised! A common failing of almost all hammy … Continue reading Basic measurements of the VK3AMP Sontheimer directional coupler for a N2PK wattmeter

VU3SQM directional wattmeter build – #2

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 directional wattmeter build – #1

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