QRP Directional Wattmeter

What is it?
This high-precision, portable wattmeter is the indispensable tool every field operator needs. Engineered for QRP and portable use, it delivers exceptional accuracy across an incredibly wide range—from 0.1 milliwatts to 10 watts.

The directional wattmeter has three key components: a directional coupler, a detector, and meter circuits. The coupler is based around the Stockton-Bruene circuit and uses two FT37-43 toroids. The detector uses the common germanium Diode 1n34a and the meter circuit uses an op-amp to amplify the detected signal and drives the analog milliamp meter.

Why did you make it?
As i was experimenting with a new QRP trx , I needed to measure very low r.f power. my diamond swr/pwr meter did not do these measurements as i could not calibrate it. So i looked around for possible solutions.

This meter did the job and can measure from 0.1mw to 10w in three ranges.

What makes it special?
Re-Designed PCB with new earth plane on top and bottom.

Uses Common Analog Ammeter

Very compact and portable design

What is Included

Bare PCB with Instructions 

 
Acknowledgment and credits goes to : W1REX-W5USJ