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[AMPS] Hamfest amp

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Subject: [AMPS] Hamfest amp
From: (Peter Chadwick)
Date: Fri, 26 Feb 1999 09:15:58 -0000
K3BU says:

>but at HF we are more
>less transparrent. 

Not totally - 27 MHz is used in diathermy machines. Interestingly, these
days, they use pulsed emissions, rather than CW for diathermy. In my case,
60 watts, prf 4kHz, duty cycle 0.16%, for sciatica.

The limits in the UK Defence Standard, and the other UK limits (which follow
the international standards) are for a maximum of 60v/m at HF:30v/m if
there's any ungrounded metalwork which could get 'hot', and give an RF burn.

The EC are moving towards 6v/m generally: that's the limit from Jan 1 this
year for continuous exposure to cellular base stations. A recent attempt to
go to 1v/m has been defeated. This was combined with a magnetic field
strength limit that gets exceeded by up to 1000 times during solar

If LF magnetic fields are so dangerous, how come there aren't excess cancer
cases in electric train drivers, exposed to very high magnetic fields during
most of their working time? Similarly with RF, there ought to be excess
cases amongst those involved with high power RF. Most of the ones I know get
to ripe old ages - maybe because at big HF transmitting stations, there's
not that much to do.........I have a photo of my father in law 'working' at
one: he's in a chair with his feet up!


Peter G3RZP

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