While browsing the internet I came across a 100W/10dB attenuator resistor with a surprisingly low price. This sparked an idea in my mind - I could potentially use this affordable attenuators as a dummy load. What's more, I could connect a diode across its output to make a simple power meter.
The attenuator serves two purposes.
1. It could function as dummy load as long as you terminate the output terminal with a 50 ohm load.
2. The rf detector is not subjected to extreme rf power as it is connected after the attenuator output.
Given the above details, I started the project as soon as the parts arrived. I had plenty of 180W/2W resistors in my junk box so I created a dummy load using them. According to my calculations, for a 30W of rf input, the 10dB / 100W resistor should effectively reduce it to approximately 3W and my 4 pieces of 180 ohm/2W resistors can safely dissipate the remaining 3W of power.
1N4148 diode is connected across the attenuator output to sample the amount of power being dissipated by the dummy load resistors. A sensitive 200uA ammeter is used to display the power measurement.
I calibrated my DIY power meter using Diamond SX200 swr/power meter as a reference. During the initial test, it exhibited a broadband characteristic. I conducted measurement validation across a range from 88MHz until 173MHz and observed a pleasant flat response. ---73 de du1vss
