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by AndrewKemendo 17 days ago
That’s wild. Radio transmission power is no joke.

I replaced the 100W FM transmitter on our college radio tower and got in front of the emitter beam for like 10 seconds and my head rung for a week. The amps and power aren’t to be messed with.

I can’t even imagine messing with 100K line that’s a solid block of copper

3 comments

I'm surprised.

Consulting an exposure limit calculator (https://www.arrl.org/rf-exposure-calculator) suggests a safe distance (FCC controlled exposure limit) for continuous (30 min) exposure from a 100w FM transmitter antenna at 100 MHz with, say, 5 dB gain is around 5 ft. For a brief exposure it's much less.

Amateur radio operators need to know this, since 100w is quite a typical power level, and they have bands (50 MHz and 144 MHz) not far from commercial FM.

How far away from the antenna were you? The antenna is usually far away from the transmitter that you were replacing.

Maybe like 1-2 feet away i was manually adjusting something on the top of a 8 foot radio tower on vandenburg hall at USAFA.
You think exposure to 100 watts at ~100 MHz is going to cause your head to ring?
Are you saying it won't? What sort of RF power density in the FM range can the human body tolerate without noticeable effect?
100 watts at 100 MHz is so low that if you spent an entire lifetime in proximity to it, you would never notice.

At 100 MHz I am unsure if transmitter even exists that can could cause harm indirectly via RF exposure. The FCC has very tight guidelines for FM transmitters at this frequency. This is just an abundance of caution.

The actual story as presented here is obviously fake: "I replaced the 100W FM transmitter on our college radio tower and got in front of the emitter beam for like 10 seconds and my head rung for a week". It's unlikely, but possible that the transmitter is mounted on the tower. In practice, no one does this. They use coax at ~100 MHz since it is so cheap and easy. Let's just assume the transmitter is mounted on the tower. The power cutoff is going to be at the bottom of the tower. You turn it off beforehand because you don't want to get electrocuted inadvertently. You don't disconnect equipment while energized. The phrase 'emitter beam' is also a dead giveaway. That phrase is only used in particle accelerator and other radiation sources.

Call Dave West who is still a radio engineer in CO and was with me on the roof in 2006 if you care so much about it
Very lucky not to have been killed by the high voltages or intense RF energy and or suffer severe burns / blindness ....
Come to think of it it wasn’t even 10 seconds, more like 2 or 3 before my ears and eyes were burning
Literally.