He used a PIC to convert the dBm readings back into watts and to calibrate the device, too. With that thought in mind, why not design a 0 - 60 dBm 1 milliwatt to watt power meter? It reads either dBm 1 - milliwatts or dBW 1 - watts. Yes, the scale is in milliamperes.
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Above is a table describing its performance. Though I cannot reach the Chinese column headings, it would appear that the claimed response is fairly flat from 1 to MHz. How does it stack up? Is it faulty or is it by design? After considerable pushing, I did get a schematic from the seller along with a repeat of the table above. Unfortunately, the document is in Chinese.
In fact, C4 and C5 are smaller than shown being pF, ie one twentieth of the size shown. C4, C5 and LS1 If you are wondering about the Obsessive attention to detail that in the long run does not result in low input VSWR at all. This article deals with fixing the first of those issues for use on HF and as high as easily achieved.
Input Z Above is a plot of input impedance from 1 to MHz. After purchase, the seller has directed me to www. The question is whether the design that is lacking can be fixed.
Improvements for HF Above, the original input circuit. First step is to get rid of the entire existing input circuit, out with the common mode choke, coupling caps and terminating resistor save the resistor if you can. Above, the input circuit cleaned off. Remove the middle right hand pad under the choke E1, but leave the via alone. The input termination will be a Above is a pic of the revised input circuit.
Much has been written about equalising the input circuit to ADs to MHz, but with some fiddling, and it really should be part of the original PCB layout rather than grafted on. The modifications here are to make it usable on HF, and as high as the simple rework allows. Above is a sweep of the modified input circuit from MHz. Input VSWR is 1. So, the input Z is controlled, we can move on an calibrate the module and observe its frequency response etc, something for the next chapter.
References Duffy, O. Dec
AD8307 Analog Devices, AD8307 Datasheet
This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc. The output waveforms can be both amplitude and frequency modulated.
Chinese AD8307 power measurement module #1
It is extremely stable and easy to use, requiring no significant external components. A single-supply voltage of 2. The input is fully differential and at a moderately high impedance 1. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use.
AD8307-EB Analog Devices Inc, AD8307-EB Datasheet
Above is a table describing its performance. Though I cannot reach the Chinese column headings, it would appear that the claimed response is fairly flat from 1 to MHz. How does it stack up? Is it faulty or is it by design? After considerable pushing, I did get a schematic from the seller along with a repeat of the table above.
The model number is a specific version of a generic that can be purchased or sampled. Status Status indicates the current lifecycle of the product. This can be one of 4 stages: Pre-Release: The model has not been released to general production, but samples may be available. Production: The model is currently being produced, and generally available for purchase and sampling. Last Time Buy: The model has been scheduled for obsolescence, but may still be purchased for a limited time.