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

R&S_ruler

Another useful ruler is made by TK5EP with the great software Galva by F5BU

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.

Ham_Radio_Calculator_byTK5EP

The file to print and cut out is on TK5EP’s website.

Following this link you reach  the Museum of Rulers with many scales.

 

 

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