In article , Mike Coslo
writes:

Hans K0HB wrote:

Mike Coslo wrote

What is the basis for 50 watts?

NCRP Report No. 86, "Biological Effects and Exposure Criteria for
Radiofrequency Electromagnetic Fields", Copyright 1986, National
Council on Radiation Protection and Measurements, and ANSI/IEEE
C95.1-1992, "Safety Levels with Respect to Human Exposure to Radio
Frequency Electromagnetic Fields, 3 kHz to 300 GHz", Copyright 1992,
IEEE, Inc.

Hans dropped in a nice bibliographic note but did NOT say HOW
he arrived at his magical 50 W limit. :-)

Way too many variables in the amateur radio "station" arrangement
to say with some kind of certainty that 50 W is THE limit for any
class. FCC already showed that with a survey of some typical
California ham stations along with measurements of fields courtesy
of a couple of other government agencies and the hams who let them
all prowl around their property.

And that 50 watts affects calss A different than Class B?

I seriously doubt that a person that cannot handle 100 watts shild have
any license. Maybe class A shouldn't be alloed to have antennas over 10
feet off the ground either. Nasy falls.

100 Watts in a 50 Ohm system has an RMS RF Voltage of 70.7.
That's on the verge of burning human skin tissue.

50 Watts in a 50 Ohm system has 50 V RMS RF...still on the verge
of burning human skin tissue, although not as badly.

100 W of RF is little, piddly stuff to what I'm used to...like 15 KW up-
close-and-personal on HF, including walking around in antenna
fields of many and varied HF emitters...and 40 KW PEP HF stuff in
antenna fields in 1955. Most of us being personal with such powers
weren't suffering ill effects and almost all of us weren't licensed in
any "classes." We got the messages through.

---------

For some really in-depth looks at radio frequency radiation, go to the
Brooks AFB website and the documents at the USAF School of
Aerospace Medicine. The following is the cover page for one of the
shorter documents released in 1996:

http://www.brooks.af.mil/afrl/HED/he...uman-exposure/
cover.gif.html

That document title number is AL/OE-TR-1996-0035. It was
prepared in 1994. Be prepared to do a little math to find the
permissible RF field strengths...not much, just a little.

There's also FCC Office of Engineering and Technology
Bulletins 56 and 65 available on the FCC RF Safety webpage.
Only a few ANSI standards are free for download (if available),
the same with the IEEE site.

Maybe Hans will reveal what kind of aluminum suit he wears when
he fires up his "2.5 KW with increased drive" HF amplifier. :-)

LHA