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So I have the misfortune of being an apartment dweller. I know that 50 watts is pretty safe as it is what first responders use on 2 meters. Am I really going to have to run around with an analyzer checking safety? That is likely to cause some probably unwarranted alarm. I can't use more than 200 watts anyway as my gear isn't rated for higher nor does it make sense to purchase such with other human beings in such close proximity. My radio itself won't do more than 100 watts without an amp.

Note that my first Ham goal is to reach my Elmer (My brother, actually) in the lower thumb area of Michigan from the Ohio river.

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  • $\begingroup$ What kind of antenna are you considering, and how far away would it be from humans and/or animals? $\endgroup$ – rclocher3 Jan 14 at 17:32
  • $\begingroup$ OK, so I read from Table 1 on Page 3 that between 80m and 15m, inclusive, is safe @100 watts but not below 15m. 12, 10 and 70 appear to be the ones to watch out for. It will not be reachable by anyone except me but it will never be more than a single room's distance away from humans / animals. I doubt my antenna has any gain but I will, of course, verify. $\endgroup$ – NonYaBidnezz Jan 14 at 17:57
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The FCC has published a bulletin OET 65B that has a table showing for VHF you don't need to evaluate the RF hazard if your effective power is 50 watts or below. For 70 cm UHF the limit is 70 watts. This does not mean it is not safe above those limits, it just means you must do an evaluation.

https://transition.fcc.gov/bureaus/oet/info/documents/bulletins/oet65/oet65b.pdf

Another table shows safe distances from antennas. It distinguishes between uncontrolled access (outside) and controlled (in your house or fenced in yard). For VHF with a 0 gain antenna in a uncontrolled environment you need a separation of 3.2 meters. So if the antenna is on a 12 foot pole you are ok.

The FCC is amending part 97 with regards to exposure limits. This will require radio operators to perform RF exposure evaluations regardless of power levels. Previous low power stations were not required to do this. The ARRL is working with the FCC to develop easy to use online RF calculators to make this task easier.

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As I recall, you're under no obligation to do RF field safety checks for radiated power up to 100 W. The only significant safety concern (assuming you're running solid state, as opposed to old vacuum tube equipment) is RF burns from actually touching the antenna other radiating element.

This is a concern, but it's worth noting that an antenna radiates just as well if made from insulated wire as it does in bare metal, so the touch exposure can be limited to connectors and cut wire ends (which can all be enclosed in heat shrink or otherwise insulated).

FWIW, if you have an antenna that's halfway efficient and reasonably well matched, your main contact range limitation on 20 and 40 meters is band conditions (which suck just now, early 2020, with the solar minimum). Even so, either of those bands should be able to reach hundreds of kilometers with 100 W and an omni antenna, so long as you aren't sending almost all of your power upward.

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As far as radiated energy, you're safe. At 100W on 40m, if you touch the antenna wire, you run the risk of RF burns (ask me how I know), and perhaps similar on 2m. But as far as problems from the RF floating around the room, it's a non-issue. The other thing that might come up is RFI, your signal getting into their TVs and stereos and such. But that's just an annoyance, not a safety issue.

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  • $\begingroup$ And RFI from 40m to TV is easily beaten with a good low-pass filter -- which most antenna "tuners" are. $\endgroup$ – Zeiss Ikon Jan 14 at 15:11

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