Re: Flouro brightness
- From: "TKM" <nomail@xxxxxx>
- Date: Wed, 17 Jun 2009 18:09:27 GMT
"Jim Hawkins" <jimhawkins@xxxxxxxx> wrote in message
news:VpCdnea4Gq14PKXXnZ2dnUVZ8v-dnZ2d@xxxxxxxxxxxxxxxx
Well, as others have said, there are electrodeless fluorescent lamps excited
"RickR" <rick@xxxxxxxxxxxxxxxxxxxx> wrote in message
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On Jun 16, 11:24 am, "Jim Hawkins" <jimhawk...@xxxxxxxx> wrote:
"Victor Roberts" <x...@xxxxxxxxxxxxxxxxxxxxx> wrote in message
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On Sat, 6 Jun 2009 15:24:24 +0100, "Jim Hawkins"
<jimhawk...@xxxxxxxx> wrote:
"Andrew Gabriel" <and...@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:4a291079$0$512$5a6aecb4@xxxxxxxxxxxxxxxxxxxx
In article <TYSdneeiX_teZLXXnZ2dnUVZ8oadn...@xxxxxxxxxxxxx>,
"Jim Hawkins" <jimhawk...@xxxxxxxx> writes:
I was a wireless fitter at RAF Leeming, England in1948
We had a T1154 HF transmitter rigged up inside the radio servicing
bay.in one of the hangars. It fed (via a window feed-through
insulator)
an apology for an aerial wire strung up outside on the end of the
hangar.
One night we stood a failed 5 foot flourescent tube with the bottom
end
resting on a wooden bench and the top in contact with the aerial
feed.
On firing up the 1154 we were almost blinded by the incredible
brilliance
with which the tube lit up. Changing the tuning caused bands of
light
to
move up and down the tube.
It was dark outside, but the enormous amount of light spilling out
of
the
windows caused some alarm.
I've no idea how much of the 1154's 50 watts of output power was
going into that tube, but 5 foot flouros were rated at around 60
watt
on the normal mains, so it must have been underrun!.
BTW, in 1948, 5' fluorescent tubes in the UK were 80W, and they were
designed to run from 80W mercury vapour lamp ballasts. As far as I
can work out from dating old fittings, the reduction to 65W started
in the late 1950's, but dual wattage 65/80W tubes were still standard
well into the 1980's, when the 58W energy saving T8 appeared.
--
Andrew Gabriel
Yes, ISTR now that those tubes were 80 watt - not 60.
Also I forgot to say that presumably some at least of the RF output was
going into the aerial rather than the tube.
Both of which things make the apparent underrun even greater!
Whilst we had no means of measuring the light output, it was
subjectively
so enormous that the lumnes/watt figure must have been way above the
sort of figures one reads about.
So is operation of flourescents in the HF radio band recognized as
leading
to high luminous efficiency ? And if so, is there any hope of utilizing
the phenomenon for commercial or industrial lighting ?
Jim Hawkins
Why do you think that the lamp was operating more
efficiently with your RF transmitter?
Fluorescent lamps operate best at low energy density. That
is why they are so large.
Your lamp was so much brighter than normal because it was
operating at higher than normal power. Any commercial
fluorescent lamp can be run at higher than rated power, and
made to produce more light. But the efficiency of light
production, that efficacy, will be lower. Just compare any
CFL to any normal linear lamp. The CFL has lower efficacy
because the energy density is higher.
--
Vic Roberts
Vic, even ignoring any power going up the aerial, this was an
80 watt tube powered by a 50 watt source !
How do you make out it was operating at higher than normal power ?
Jim Hawkins- Hide quoted text -
- Show quoted text -
To expand the question:
How much power (from the ballast for an 80W lamp) actually gets to the
phosphor?
RickR
So why use 60 Hz and ballasts when RF excitation needs no
ballasts, no tube startup heaters and is apparently so much more effective
?
I admit we only ran that 'dud' tube for a half-hour or so, so what the
life
would have been I've no idea, but the brilliance was not just a lot better
than normal, it was blindingly bright.
Jim Hawkins
by RF energy on the market and they work just fine. See:
http://livedesignonline.com/mag/lighting_leading_lamps_lighting/ and
http://www.sylvania.com/BusinessProducts/LightingForBusiness/Products/Lamps_OLD/Fluorescent/Icetron/
for example. RF-excited lamps may not need a ballast; but they do need an RF
generator which, at the moment, is substantially more expensive than a
standard high-frequency electronic ballast.
The main advantage of RF fluorescent systems is very long lamp life which
gets traded off against the life of the RF driver and the cost of additional
shielding required to keep the stray RF inside the luminaire. Even integral
CFLs have to carry an FCC label because they radiate some RF. And, the RF
fluorescent lamp systems,so far, are substantially more expensive than
conventionally-ballasted systems which limits the RF systems to applications
where maintenance is difficult or expensive - some streetlighting, tunnel
lighting, etc.
I've used fluorescent lamps to tune the RF output of ham radios (adjust for
maximum brightness) and I've seen tricks with fluorescent lamps inside of
microwave ovens. Powering an 80 watt standard tube with 50 watts of RF well
coupled to the lamp is going to make the tube bright - no question about
that; but unless the light output and the power input are measured somehow,
there's no way to tell if there's any significant efficiency increase. The
data that I've seen says there's not.
Terry McGowan
.
- References:
- Flouro brightness
- From: Jim Hawkins
- Re: Flouro brightness
- From: Andrew Gabriel
- Re: Flouro brightness
- From: Jim Hawkins
- Re: Flouro brightness
- From: Victor Roberts
- Re: Flouro brightness
- From: Jim Hawkins
- Re: Flouro brightness
- From: RickR
- Re: Flouro brightness
- From: Jim Hawkins
- Flouro brightness
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