Re: Safe Sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>

Yeah, you should see the, or rather hear, a waveguide arc in all its glory.
Heard one last week at about 5.5 MW peak power at 3.5 GHz.  Totally nasty.
Made a whole room full of the boldest and oldest engineers and technicians
alike run for cover.

Dan





 > Interesting.. at 196 MHz, of course, skin effect will put most of the
power
 > at the surface (unlike at 100 kHz'ish TCs, where the high resistance of
the
 > body makes for a fairly large (RF)skin thickness).  I wonder how the poor
 > guy got 2A at 196 MHz? That's   TV channel 10 (192-198 MHz) in the US (I
 > don't have the channel frequencies for Australia handy..but it's in the
 > same ITU band), and I'll bet you could get 2 Amps (if not a lot more) if
 > you happened to grab the  transmitting antenna or an exposed feed
terminal.
 > 50 kW at 50 ohms is around 32 Amps...
 >
 > I'd change the first line of the abstract to be:
 > RF electrocutions are not commonly reported.
 >
 > I'll bet that there are a lot more RF burns that actually occur than are
 > reported.   Only the most egregious or ones with lasting effects would
show
 > up in a doctor's office.
 >
 >
 > At 06:06 PM 12/2/2002 -0700, you wrote:
 > >Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
 > ><DanReind-at-aol-dot-com>
 > >
 > >Hello all,
 > >
 > >I was doing some digging on pubmed as part of my work, looking for some
 > >information on radiofrequency burns.  Found an abstract for a very high
 > >frequency burn that I thought might be off interest.
 > >
 > >Cheers,
 > >
 > >Dan Reinders
 > >
 > >
 > >
 > >"Occup Med (Lond) 1999 Sep;49(7):459-61 Related Articles, Links
 > >
 > >
 > >Radiofrequency electrocution (196 MHz).
 > >
 > >Hocking B, Westerman R.
 > >
 > >International Diabetes Institute, Caulfield, South Vic., Australia.
 > >bruhoc-at-connexus-dot-net.au
 > >
 > >Radiofrequency (RF) electrocutions are uncommon. A case of electrocution
 > >at 196 MHz is presented partly because there are no previous reports with
 > >frequencies as high as this, and partly to assist in safety standard
 > >setting. A 53-year-old technician received two brief exposures to both
 > >hands of 2A current at 196 MHz. He did not experience shock or burn.
 > >Progressively over the next days and months he developed joint pains in
 > >the hands, wrists and elbows, altered temperature and touch sensation and
 > >parasthesiae. Extensive investigation found no frank neurological
 > >abnormality, but there were changes in temperature perception in the
palms
 > >and a difference in temperature between hands. His symptoms were partly
 > >alleviated with ultra-sound therapy, phenoxybenzamine and glyceryl
 > >trinitrate patches locally applied, but after several months he continues
 > >to have some symptoms. The biophysics and clinical aspects are discussed.
 > >It is postulated that there was mainly surface flow of curr!
 > >ent and the micro-vasculature was effected. Differences to 50 Hz
 > >electrocution are noted. Electrocution at 196 MHz, even in the absence of
 > >burns may cause long-term morbidity to which physicians should be
alerted.
 > >Safety standards should consider protection from electrocution at these
 > >frequencies."
 >
 >
 >
 >
 >
 >
 >