Useful cardboard rulers
I really like smart rulers.
Slide or fixed, circular or rectangular they are all useful gadgets and have a place in my lab.
I’ve found a new one for my collection at the last European Microwave Week 2014 at the Rohde & Schwarz stand.
No pretty frills, it converts at a glance Watts to dBm and to Volt (Z=50 Ohm) and calculate a ratio, voltage or power, in dB
It’s a circular SWR/Return Loss/ Gain calculator. Aligning the forward power on the external disk with the reflected power on the internal disk, we can see the SWR and the RL through the little window.
The file to print and cut out is on TK5EP’s website.
Following this link you reach the Museum of Rulers with many scales.