I would like to contribute to this forum with this project I built long ago (1995).
It is a RF step attenuator for lab use, main features are:
- 50 ohm input/output impedance,
- very good performance from DC to 500 MHz,
- 8 attenuation cells: 1, 2, 4, 8, 16, 16, 16, 16 dB allows you to select attenuation from 0 to 79 dB in 1 dB steps,
- BNC input/output connectors,
- each cell is operated with a DPDT miniature slide switch.
I made it in three versions, two of them with PCB stripline technology in order to make it usable at high frequencies. I've tested and characterized them with:
- Anritsu mod.MS610B (10 KHz ÷ 2 GHz ; Zi = 50 ohm) spectrum analizer with built-in 50 ohm dummy load,
- Racal-Dana mod.9081 (5 MHz - 540 MHz ; -120 dBm ÷ +10 dBm; Zo = 50 ohm) syntesized signal generator.
You can see a photo gallery of this project on my facebook page:http://www.facebook.com/media/set/?set=a.1934259518611.2115379.1305998984&type=3
A project description (unfortunately in italian, but if anybody is interested to I can traslate in english) in pdf is downloadable from: http://www.box.com/shared/yq460xfvnd
Another pdf file with some measures performed on prototypes (also pdf) is downloadable from: http://www.box.com/shared/3rr2ant105
Here you can download an excel spreadsheet with calculations for pi and T attenuation cells from 1 to 20 dB and their approximations using standard E24 resistors: https://www.box.com/s/txavd5irqg0t50bv3ze1
Finally, I have recently made a pcb with Proteus 7.10 (thanks to Sonsivri forum for this firmware !!! ): ISIS schematics, ARES pcb layout and gerber files are downloadable here: https://www.box.com/s/wdqeqlaqe8dv5qbvsnpv
I hope this little contribution to the forum may be helpful to somebody. I'm glad to answer to any question about this project.
Greetings to everybody,