On Thu, Dec 18, 2003 at 12:44:18AM -0800, H.C. Croon enlightened us
thusly
> > On Fri, Dec 12, 2003 at 09:19:27AM -0800, Torelli, Bruce enlightened
> > us thusly
> > >
> > > I remember reading an instruction placard for leak testing an old
> > > microwave years ago. All you needed to do was pass a small 5"-6"
> > > florescent tube near the door parting surfaces. The tube would
> > > supposedly glow if there was leakage. I never tried it.
> >
> > It does. The technique is commonly used in RF generators
> > (13.56/27.12/41.xx Mhz). But at that frequency, you need a
> > considerable amount of power to light the tube at all. You don't
> > believe it until you see it, but I have seen it. If that much
> > microwave power was excaping, your eyeballs would be cooked before
> > you could see if it was lighting :-/.
> >
> > The RF generators are one big tank oscillator made from a power
> > triode thermionic valve, and used for rapid curing of glue and
> > plastic welding. They suddenly went a bit scarce after CE approval
> > ...
> >
> Hi Declan,
>
> I doubt. Having a fluorescenct tube for p.e. 8W for full light, a
> fraction of a Watt of power would suffice for local illumination at a
> lower, but observable, light intensity. I remember stories of people
> living in the neighbourhood of broadcast antenna's. The fluorescent
> tubes in their houses were lighting spontaneously. They were not
> cooked!
I for one would certainly not remian in a house where bulbs lit
spontaneously!
Broadcasting can be at nasty frequencies. In this country there was
regular enough trouble with mobile phone repeaters, and investigations
are being done about the unusually high cancer rates in the locality of
Electric Power pylons. When word got into some small villages that a
local mast or tower was to get a mobile phone repeater, they simply
picketed the area in such force that the installation was prevented.
Others were installed by night, and subsequently vandalized or removed.
I personally did the bulb experiment with a 2.5KW RF generator, and an 8
inch tube. This generator had a valve with 4.5KV on it passing 0.56 amps
or so (2.52KW). The current was read on an A.C. Ammeter. I had the side
off. The output was wide strips of flexible brass leading to two sides
of a clamp about 18 inches long, which were for clamping plastic
sheeting. This output was of course capacitor fed, and the frequency
was 13.56Mhz.
With the jaws open, and the generator on (maximum voltage swing) I could
get no visible light from the inside of the generator or the brass
strips. When I put the bulb parallel with and close to the clamp jaws, I
did get light. That seems to indicate a fair deal of power was required
to light the bulb. The visibility is not only light, but a change of
colour to a yellowish shade of light. Subsequent tests on Plastic
indicated the generator was up to normal power output.
I am told likewise that larger bulbs (or some section of them) also
'light' in the presence of rf, and think the effect on the gas of the
particular frequency is a factor that cannot be ignored
--
With best Regards,
Declan Moriarty.
--
Author: Declan Moriarty
INET: [EMAIL PROTECTED]
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