Attenuator for Tx Monitor output

[RadioTop]

Despite your recommendation to prefer receiving by air, I intend to connect the Pira P175 to our FM transmitters. They offer a "Monitor RF" output labelled "-30dB". Max. RF power at the Tx output is 100 W. Sorry, I'm not good at dB-maths. What attenuator do I need not to damage the P175?

[Jan]

For 100 W the -30 dB is 0.1 W. Thus it's preferred to use additional 20 dB attenuator so the resulting power is 1 mW. A 30 dB attenuator can be used as well.