[Elecraft] Was Amplifier - Now RF exposure limits

[Vic Rosenthal]

I strongly disagree. The heating effect - which is the only scientifically verifiable effect from RF exposure - is far smaller at HF than radar frequencies. Yes, you don't look into a horn antenna of an operating radar transmitter, but a 20 meter dipole is a different story entirely. The exposure limits mandated by the FCC (and by the authorities in this country too) serve only to cover various butts against opportunistic lawsuits. 

Vic 4X6GP

> On 7 Apr 2017, at 22:55, Gmail - George <gdanner12 at gmail.com> wrote:
> 
> Ed & Brian,
> My father had severe health consequences from working in a classroom with 
> operating military radars!
> 
> Since the adoption of OET 65 in the late 90s, all licensees (including Hams) 
> have had the responsibility to insure their station is in complete 
> compliance with RF exposure limit guidelines.
> 
> Most likely during your last license renewal or application for a new 
> license, you checked a box stating you would insure compliance with 
> non-ionization radiation limits.
> Those guidelines are contained in bulletin OET 65.
> For Hams OET 65 Supplement B 
> (https://transition.fcc.gov/bureaus/oet/info/documents/bulletins/oet65/oet65b.pdf) 
> gives us some shortcuts to insure compliance without the tedious 
> calculations. Many of the tables were provided by ARRL & the W5YI Group.
> 
> There are also calculators available on the internet to make it quite easy. 
> Googleing "amateur radio oet 65 calculator" returned many to choose from.
> 
> The only caveat I will give is that most of the shortcuts and calculators 
> are for a single transmitting antenna at a specific location. Multiple 
> radiating antenna WILL change the protection distances - Field Day & group 
> contesting come to mind!
> 
> Use to be we had to submit OET 65 compliance statements when licensing all 
> transmitters for Broadcast Stations ranging from 150 MHz to 23 GHz. I 
> believe we finally could use just a blanket cover statement ; but it has 
> been a while since I licensed a non-Ham transmitter.
> 
> You do need to insure you are in compliance - to protect your family, 
> friends, neighbors and yourself.
> 
> 73
> George
> AI4VZ
> 
> 
> From: brian
> 
> "Considered dangerous" isn't quite right.  The jury is out of the exact
> danger levels of RF for all the various frequencies.  These distances
> are more of an accepted limit that protects you from inquiries regarding
> RF exposure.  Pointing to the distances being met helps get you off the
> hook.
> 
> People will be surprised to see how small the distances these
> calculations are-- especially at lower frequencies.
> 
> One note often overlooked. The distance is defined as the distance from
> feedpoint (usually center) of the antenna.
> 
> Also the duty cycle can be considered in the calculation.  There are
> stock duty cycles for SSB and CW given in the documentation.
> 
> Antenna gain may have to be included.
> 
> It used to be that anything at 100 watts and below at HF was exempted.
> I believe that has changed.
> 
> 73 de Brian/K3KO
> 
> 
> 
>> On 4/7/2017 16:06 PM, Edward R Cole wrote:
>> In the USAmerica ham's now have the *responsibility* of determining the
>> safe operating zones for each antenna per FCC regulation.  I doubt many
>> ever do the calculation.  Fortunately Australian ham Doug MacArthur (sk)
>> VK3UM (a well known eme'r) has written a program which you can download
>> for free.  I will simulate the emf fields base on your input data like
>> antenna, power, height, band and produces the legal exclusion zones
>> where RF exposure is considered dangerous.
>> 
>> http://www.vk3um.com/emr%20calculator.html
>> 
>> Its not hard to use and provides some interesting if not surprising info
>> about your station safety.
>> 
>> As I already stated, it is the legal requirement for all US hams to have
>> evaluated safe range for humans before operating.
>> 
>> Eg:  half-wave dipole, 1400w, line loss 0.5 dB, 14.2 MHz: exclusion =
>> 3.06m radially; safe height 2.60m for FCC.  Also provides ARPNSA and CEU
>> radiation limits.
>> 
>> 73, Ed - KL7uW
> 
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