Oldest UK television discovered
Java Jive
http://news.bbc.co.uk/1/hi/technology/8159406.stm
======================================
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Java Jive
make that an average inflation rate of 239% a year!
Ivan
"Java Jive" <ja...@evij.com> wrote in message
news:8u1b65dcbmm29furs...@4ax.com...
>I wonder if 60 guineas then was really equivalent to �11,000 today? I
> make that an average inflation rate of 239% a year!
>
According to google 60gns (�63) back then would work out at around �2,300 in
today's money, not �11,000..
David
http://www.thetelegraphandargus.co.uk/news/4503145.UK_s_oldest_TV_is_found___to_work_/?ref=eb
--
Regards,
David
FREESAT HD as it is now it is a joke.
Clive
<ja...@evij.com> writes
>Get ready for a thread of misty-eyed nostalgia ...
>
>http://news.bbc.co.uk/1/hi/technology/8159406.stm
EMI and RCA to create the first camera tube, which I believe was called
the Emiscope.
--
Clive
Java Jive
50% pa! As I've lived through 58 of the intervening 73 years, and
don't remember inflation ever even reaching 50%, even during the Heath
government, I still think something must be wrong.
On Tue, 21 Jul 2009 10:38:35 +0100, "Ivan" <ivan'H'ol...@yahoo.com>
wrote:
>
> According to google 60gns (�63) back then would work out at around �2,300 in
> today's money, not �11,000..
======================================
Max Demian
news:t6EAJ3CL...@yewbank.demon.co.uk...
Where does it say that Yogi Bear invented TV?
--
Max Demian
David
"Max Demian" <max_d...@bigfoot.com> wrote in message
news:7cliedF...@mid.individual.net...
> "Clive" <Cl...@yewbank.demon.co.uk> wrote in message
> news:t6EAJ3CL...@yewbank.demon.co.uk...
>> In message <ag1b65hga4d8c6qkj...@4ax.com>, Java Jive
>> <ja...@evij.com> writes
>>>Get ready for a thread of misty-eyed nostalgia ...
>>>
>>>http://news.bbc.co.uk/1/hi/technology/8159406.stm
>> What rubbish, Logie-Baird didn't invent the TV, it was an effort by both
>> EMI and RCA to create the first camera tube, which I believe was called
>> the Emiscope.
>
From my T&A post
'The competition was set up by Digital UK and Iain Logie Baird, television
curator at the National Media Museum and grandson of the inventor of TV,
John Logie Baird.'
Richard Brooks
screen pointing to camera and uttering the immortal lines "Have you
been injured in an accident at work..."
Martin Jay
It depends which measure of inflation you use.
We usually think of inflation relative to prices, however wage
inflation, for example, tends to increase at a faster pace.
According to <http://www.measuringworth.com/ukcompare/> a wage of 60
guinea in 1936 is equivalent to one of �11,635 today.
--
Martin Jay
Ivan
"David" <david...@tesco.net> wrote in message
news:h442mf$lfg$1...@news.albasani.net...
>
> http://www.thetelegraphandargus.co.uk/news/4503145.UK_s_oldest_TV_is_found___to_work_/?ref=eb
>
>
Every report I've read on this says that 60 guineas back in 1936 represents
the equivalent of �11,000 today, whereas a couple of currency converters
I've managed to find on Google puts the figure @ somewhere around �3,300.
<http://www.moneysorter.co.uk/calculator_inflation.html>
Peter Duncanson
>On 21 Jul,
> Java Jive <ja...@evij.com> wrote:
>> On Tue, 21 Jul 2009 10:38:35 +0100, "Ivan" <ivan'H'ol...@yahoo.com> wrote:
>> >
>> > According to google 60gns (�63) back then would work out at around �2,300
>> > in today's money, not �11,000..
>
>> That certainly sounds more reasonable, but it's still an average of
>> 50% pa! As I've lived through 58 of the intervening 73 years, and
>> don't remember inflation ever even reaching 50%, even during the Heath
>> government, I still think something must be wrong.
>>
>times40 is about right. inflation is compound so you can't just divide by the
>intervening years.
>
Yes.
Using the calculator at the following URL �63 becomes �2,219.01 after 73
years assuming 5% annual compound interest.
http://www.theconvertersite.com/finance/calculators/compoundinterestcalculator.php#results
>See <http://www.crowsnest.co.uk/north/rpi.htm>
--
Peter Duncanson
(in uk.tech.digital-tv)
Java Jive
======================================
Paul D.Smith
> make that an average inflation rate of 239% a year!
Surely more interesting to us nerds is the Aurora standards converter which
they were using. Apparently this costs about $599 and you still need a
modulator. But if you have a 405 line TV which you want to use to watch
More4 in B&W...
Paul DS.
airsmoothed
The 11,000 GBP figure has been calculated using the difference in
average earnings over the intervening years:-
http://www.measuringworth.com/ukcompare/
Arguably I'd say that a more meaningful measure of relative cost than
RPI comparison.
Ian
<richar...@vickers-armstrongs.com> writes
Logie -Baird was at a reception to introduce the TV to the World.
On being congratulated by one man, Baird replied "aye, but there's
bugger all on".
--
Ian
Owain
> ... He chucked it in when the first images were of a man walking across
> screen pointing to camera and uttering the immortal lines "Have you
> been injured in an accident at work..."
It would have been BBC at that point, so a stern voice saying "Radio
licencing ... it's all in the card index"
Owain
Madge
> Get ready for a thread of misty-eyed nostalgia ...
>
> http://news.bbc.co.uk/1/hi/technology/8159406.stm
>
> ======================================
No! It seems strange that, "Iain Logie Baird, the curator of television at
the museum, said it is a thrill to see the Marconiphone working." without
mentioning the work of John Logie Baird http://www.bairdtelevision.com/.
Crazy, also as it states that the Cathode Ray Tube TV mentioned is not in
its original state either.
--
http://www.madge.tk Madges Links
Clive
<max_d...@bigfoot.com> writes
>Where does it say that Yogi Bear invented TV?
--
Clive
Clive
<deletethisbit...@yahoo.com> writes
>No! It seems strange that, "Iain Logie Baird, the curator of television at
>the museum, said it is a thrill to see the Marconiphone working." without
>mentioning the work of John Logie Baird
>http://www.bairdtelevision.com/.
>
>Crazy, also as it states that the Cathode Ray Tube TV mentioned is not in
>its original state either.
used were RADAR tubes which were not only green in colour but also used
electrostatic plates inside the tube for beam landing instead of the CRT
(usual) method of using electromagnets around the neck/bowl of the tube,
which was standard even in the days of the colour shadow mask (RCA
invented) tube. I won't even go into "ion trap magnets" here.
--
Clive
Ivan
receivers using surplus VCR 97 CRTs?.. I was also under the impression
(although I could well be wrong) that prewar tubes were 60� triodes with
magnetic deflection with more often than not the final anode powered by the
dreaded 50 cycle EHT.
Clive
<ivan'H'ol...@yahoo.com> writes
>> As I understand it, and am prepared to be corrected, the first tubes
>>used were RADAR tubes which were not only green in colour but also
>>used electrostatic plates inside the tube for beam landing instead of
>>the tube, which was standard even in the days of the colour shadow
>>mask (RCA invented) tube. I won't even go into "ion trap magnets" here.
>> --
>I thought that was came later (postwar) with enthusiasts building their
>own receivers using surplus VCR 97 CRTs?.. I was also under the
>impression (although I could well be wrong) that prewar tubes were 60�
>triodes with magnetic deflection with more often than not the final
>anode powered by the dreaded 50 cycle EHT.
to the late fifties early sixties, everything before that I was either
told or learned. 50 cycle EHT sounds like a death threat to anybody
too close, but I am keen to know more if you can post it.
--
Clive
Mike Thomas
> Surely more interesting to us nerds is the Aurora standards converter
> which they were using. Apparently this costs about $599 and you
> still need a modulator. But if you have a 405 line TV which you
> want to use to watch More4 in B&W...
$260 now for the latest model. Or $965 for multi-standard.
Ivan
I managed to find this warning about restoring older sets with mains derived
EHT.. "It is impossible to over-stress the dangers of mains-derived EHT
systems found in pre-war and some early post-war sets. These systems are
lethal, so treat them with respect. Unlike modern EHT systems, which are
limited in the amount of current they can supply, these older systems using
transformers straight off the mains can deliver enough current to kill an
army. If you are not sure what you are doing, please ask a friendly
colleague. For testing, use an EHT meter; they are still used by the TV
servicing trade" http://www.bvws.org.uk/405alive/tech/eht.html.
I also found this in an item related to TV's manufactured during 1937..
"After just a year, there was a definate trend in C.R.T. design away from
the electostatically deflected type to magnetically deflected types, within
another two years, the electrostaic C.R.T. was to have almost completely
dissapeared from new television models"
http://www.thevalvepage.com/tvyears/1937/tvy1937text.htm
There are also some really interesting associated pages WRT information
along with photo galleries of prewar receivers, for anyone interested IMO
well worth a browse .
>
>
Mike Thomas
> What rubbish, Logie-Baird didn't invent the TV, it was an effort by both
> EMI and RCA to create the first camera tube, which I believe was called
> the Emiscope.
EMI's Emitron wasn't the first electronic camera tube by far, but maybe the
first really practical one, and the first to go into service for regular
broadcasts because it was chosen by the BBC.
Baird would later pay Philo Farnsworth (the original American inventor of
the electronic camera tube) for electronic equipment and access to the
original patents, so that he could compete with Marconi-EMI in the UK.
Richard Brooks
> In <8f7849f6-0494-4488...@a7g2000yqk.googlegroups.com>,
I didn't think that the BBC was formed as soon as he switched the
thing on? Huh! You learn something everyday.
R. Mark Clayton
> make that an average inflation rate of 239% a year!
Your maths is crap - it would be 7.33% per annum
But so is theirs..
Actually it is probably more like �1,500 to �2,000
Although rebased for earnings rather than prices their figure is better.
>
> On Tue, 21 Jul 2009 10:11:38 +0100, Java Jive <ja...@evij.com> wrote:
>
>> Get ready for a thread of misty-eyed nostalgia ...
>>
>> http://news.bbc.co.uk/1/hi/technology/8159406.stm
>
> ======================================
>
R. Mark Clayton
It says "television pioneer" not inventor [now].
Anyway he is credited with inventing TV - the important element being the
transmission of the signal.
Marconi-Emi engineered the 405 black and white [electronic] system adopted.
R. Mark Clayton
> In message <op.uxfayzd6f11096@loutside>, Madge
> <deletethisbit...@yahoo.com> writes
>>No! It seems strange that, "Iain Logie Baird, the curator of television at
>>the museum, said it is a thrill to see the Marconiphone working." without
>>mentioning the work of John Logie Baird http://www.bairdtelevision.com/.
>>
>>Crazy, also as it states that the Cathode Ray Tube TV mentioned is not in
>>its original state either.
> As I understand it, and am prepared to be corrected, the first tubes used
> were RADAR tubes
Radar - not invented then, but oscilliscopes were.
R. Mark Clayton
Further to last a bit of Googling identifies the TV and the CRT mechanism: -
"
MARCONI 702 TELEVISION (1936)
The MARCONI 702 was a 12" mirror lid TV. It used magnetic deflection and
electrostatic focusing. The set was also available in a different cabinet
under the HMV brand.
"
Electrostatic deflection was quickly abandoned as the rapid line rate
required huge voltages and voltage swings to bend the beam. Much easier to
use coils and increase the current. Focus OTOH does not require a huge
voltage and should be fairly static.
Mike Thomas
> "David" <david...@tesco.net> wrote
>> From my T&A post
T&A post. Oooooh.
> Anyway he is credited with inventing TV - the important element being the
> transmission of the signal.
A Russian has a good claim for that, it seems.
http://en.wikipedia.org/wiki/Boris_Rosing
JLB was always "the inventor of TV" for us, but his claim seem to get
progressively qualified as we learn more from elsewhere in this
international information age.
Brian Gaff
Those were the days.
Brian
--
Brian Gaff - bri...@blueyonder.co.uk
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in the display name may be lost.
Blind user, so no pictures please!
"Java Jive" <ja...@evij.com> wrote in message
news:ag1b65hga4d8c6qkj...@4ax.com...
> Get ready for a thread of misty-eyed nostalgia ...
>
> http://news.bbc.co.uk/1/hi/technology/8159406.stm
>
Brian Gaff
things were bought on hire purchase.
Not seen the article as yet, but how did they actually test it?
Brian
--
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Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Java Jive" <ja...@evij.com> wrote in message
news:s34b65lqs6rsbpgnm...@4ax.com...
> That certainly sounds more reasonable, but it's still an average of
> 50% pa! As I've lived through 58 of the intervening 73 years, and
> don't remember inflation ever even reaching 50%, even during the Heath
> government, I still think something must be wrong.
>
> On Tue, 21 Jul 2009 10:38:35 +0100, "Ivan" <ivan'H'ol...@yahoo.com>
> wrote:
>>
>> According to google 60gns (�63) back then would work out at around �2,300
>> in
>> today's money, not �11,000..
>
Dave Plowman (News)
Clive <Cl...@yewbank.demon.co.uk> wrote:
> As I understand it, and am prepared to be corrected, the first tubes
> used were RADAR tubes which were not only green in colour but also used
> electrostatic plates inside the tube for beam landing instead of the CRT
> (usual) method of using electromagnets around the neck/bowl of the tube,
> which was standard even in the days of the colour shadow mask (RCA
> invented) tube. I won't even go into "ion trap magnets" here.
Thought CRT TV came before radar? Wasn't it not in use until after WW2
started?
--
*With her marriage she got a new name and a dress.*
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Ivan
"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
news:u2q9m.59288$OO7....@text.news.virginmedia.com...
>
> Anyone remember ion traps on tube necks?
>
>
kettles and warm woolen mittens, brown paper packages tied up with strings..
Ivan
large amount of cases was nothing more than the fibre strap around the tube
neck simply letting go.. a few minutes' work in exchange for a couple of
quid in the back pocket.. oh yes, 'definitely' happy days!
"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
news:u2q9m.59288$OO7....@text.news.virginmedia.com...
>
Clive
<ivan'H'ol...@yahoo.com> writes
>
middle of the face of the tube being burnt out, yes I remember them.
--
Clive
Clive
<da...@davenoise.co.uk> writes
>Thought CRT TV came before radar? Wasn't it not in use until after WW2
>started?
world war.
--
Clive
Bill Wright
"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
news:u2q9m.59288$OO7....@text.news.virginmedia.com...
>
> Those were the days.
> Brian
I had a monochrome monitor in 1999 that hadn't got one but clearly needed
one.
Bill
Steve Terry
"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
news:u2q9m.59288$OO7....@text.news.virginmedia.com...
>
>
Steve Terry
Roderick Stewart
> It says "television pioneer" not inventor [now].
>
> Anyway he is credited with inventing TV - the important element being the
> transmission of the signal.
It depends on what you mean by "invent". It is historical fact that JLB was
the first person do demonstrate a real working television system, if you
accept that this means the analysis of an image into an electrical signal
and is subsequent reconstitution into an image. The "transmission" in the
case of Baird's demonstration, was only along a few feet of cable, but it
demonstrated a new technique for the first time. It would have been
uneccessary to demonstrate the additional technique of transmitting
electrical signals by wireless as it had been done already.
Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/
Ivan
<m...@privacy.net> wrote in message news:507E8E107D%brian...@lycos.co.uk...
> On 21 Jul,
> Clive <Cl...@yewbank.demon.co.uk> wrote:
>
>> As I said, "I'm prepared to be corrected", my knowledge only goes back
>> to the late fifties early sixties, everything before that I was either
>> told or learned. 50 cycle EHT sounds like a death threat to anybody
>> too close, but I am keen to know more if you can post it.
>
> way
> to get a bright enough picture to project. I suspect these smaller tubes
> were
> electrostatic deflection, but I was too young at the time to investigate.
>
> --
>
All the ones I ever came across used conventional line fly back techniques
and voltage multipliers, I've even got a few mementos from those far off
days still kicking around, you can see them here.
http://picasaweb.google.co.uk/Anth230542/ProjectionOBXS?authkey=Gv1sRgCJuBjsrU9uTBYQ&feat=directlink
Dave Plowman (News)
Indeed. But what we now know as radar wasn't available at the start of the
war. Dunno when development first started - despite being at school with
Prof Jones's son Robert. ;-)
--
*See no evil, Hear no evil, Date no evil.
Max Demian
>>I thought that was came later (postwar) with enthusiasts building their
>>own receivers using surplus VCR 97 CRTs?.. I was also under the
>>impression (although I could well be wrong) that prewar tubes were 60�
>>triodes with magnetic deflection with more often than not the final anode
>>powered by the dreaded 50 cycle EHT.
> As I said, "I'm prepared to be corrected", my knowledge only goes back to
> the late fifties early sixties, everything before that I was either told
> or learned. 50 cycle EHT sounds like a death threat to anybody too
> close, but I am keen to know more if you can post it.
Surely it was the inclusion of a large resistor in series with the EHT that
made it safe rather than whether it was generated from mains or the line
scan transformer?
--
Max Demian
Terry Casey
says...
> made it safe rather than whether it was generated from mains or the line
> scan transformer?
Such a resistor could only be added *after* the lethal part of a mains
derived EHT supply! It might make the EHT safer at the point of use, ie:
the CRT, but the EHT generator would not be any less lethal (and the
presence of such a resistor could lead to a false sense of security in
the unwary.)
The only effect would be to destroy EHT voltage regulation. Remember
that any fault finding on the EHT section would be carried out *before*
this 'safety' resistor.
When I started work in 1960 I met a man who had been on the receiving
end of one of these things - and lived to tell the tale. The smoothing
capacitors were oil-filled metal cased units [1] with two terminals on
top. Like these: http://tinyurl.com/mkj3k5
He had managed to get his arm across the top of one and had two small
white scars on his forearm as a momento!
[1] I encountered a later version of these on a number of occasions,
used with early line scan generated supplies. They had a much lower
capacity 500pF or 1000pF, due to the much higher frequency. They were
made by TCC under the Visconol trademark. These were cylindrical with a
metal base from which protruded an threaded rod for mounting and earth
connection. The case was hard plastic with the other terminal on the
top. Like this: http://tinyurl.com/lbynbm
They were rendered obsolete when CRT manufacturers incorporated a
capacitor into the tube design by adding an aquedaq (metalised paint)
coating to the outside of the CRT bulb.
--
Terry
Clive
Casey <k.t...@example.invalid> writes
>In article <7co5cvF...@mid.individual.net>, max_d...@bigfoot.com
>says...
>>
>> "Clive" <Cl...@yewbank.demon.co.uk> wrote in message
>> news:D9k7I3EL...@yewbank.demon.co.uk...
>>
>> Surely it was the inclusion of a large resistor in series with the EHT that
>> made it safe rather than whether it was generated from mains or the line
>> scan transformer?
--
Clive
Ivan
Just in case my previous post didn't show up on your server I'll repost it
here, as it contains dire warnings concerning the extreme dangers of messing
around with an mains-derived EHT for the uninitiated.. or come to that even
the initiated!
Johnny B Good
from Terry Casey <k.t...@example.invalid> contains these words:
And, you forgot to add, a similar coating on the inside of the tube to
turn it into a "Leyden Jar" capacitor.
--
Regards, John.
Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.
Jim
> JLB was always "the inventor of TV" for us, but his claim seem to get
> progressively qualified as we learn more from elsewhere in this
> international information age.
And poor old Alan Blumlein hardly ever gets mentioned in this context
although he contributed a huge amount to the 405-line EMI system AIUI.
Max Demian
news:MPG.24d0ff957...@news.virginmedia.com...
> In article <7co5cvF...@mid.individual.net>, max_d...@bigfoot.com
> says...
>>
>> "Clive" <Cl...@yewbank.demon.co.uk> wrote in message
>> news:D9k7I3EL...@yewbank.demon.co.uk...
>>
>> Surely it was the inclusion of a large resistor in series with the EHT
>> that
>> made it safe rather than whether it was generated from mains or the line
>> scan transformer?
>
> Such a resistor could only be added *after* the lethal part of a mains
> derived EHT supply! It might make the EHT safer at the point of use, ie:
> the CRT, but the EHT generator would not be any less lethal (and the
> presence of such a resistor could lead to a false sense of security in
> the unwary.)
>
> The only effect would be to destroy EHT voltage regulation. Remember
> that any fault finding on the EHT section would be carried out *before*
> this 'safety' resistor.
So what precisely made line scan EHT generators so much safer than the mains
generated type?
--
Max Demian
Ivan
"Terry Casey" <k.t...@example.invalid> wrote in message
news:MPG.24d0ff957...@news.virginmedia.com...
IIRC they were also to be found in a 16" Ferguson chassis (with a English
Electric metal coned tube) in a voltage doubler circuit, in which they
frequently went short, I've seen them disconnected by the local bodger to
restore the picture, which as you can imagine did wonders for the EHT
regulation.:o)
Clive
<max_d...@bigfoot.com> writes
>So what precisely made line scan EHT generators so much safer than the mains
>generated type?
had no need to be regulated, (variation just meant smaller brighter
pictures if the voltage went up) and was normally 17 to 18 kV at very
low current. Colour changed things, as EHT had to be regulated to keep
the three beams in registration which meant higher voltage and
stabilization. EHT moved up to 25kV the highest you could use where any
X-rays generated by the phosphors would be absorbed by the lead glass of
the tube faceplate, but stabilization also meant keeping a bit in
reserve so unusually bright pictures didn't take to much out of an under
performing system, this is because the shadowmask dumps about 2/3 of the
current straight back to the ground of the system. I don't know about
now, but early colour systems whether using a straight transformer and
half wave rectifier (know as the smoke stack because of all the fires
they produced), or the more common 8kV transformer plus tripler
arrangement, all carried warnings that contact with the EHT system could
result in death.
--
Clive
Adrian C
Oh you cruel cruel cruel man! That is a nasty earworm for me!!!!
--
Adrian C
Roderick Stewart
> So what precisely made line scan EHT generators so much safer than the mains
> generated type?
Higher output impedance.
Graham.
"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
news:u2q9m.59288$OO7....@text.news.virginmedia.com...
> Anyone remember ion traps on tube necks?
>
> Those were the days.
> Brian
And on the subject of tube-neck magnets, I used to think "Blue Lateral"
would
be cool name for a pop group or mobile disco.
--
Graham.
%Profound_observation%
Java Jive
King Edward II and the Red Hot Polkas!
On Wed, 22 Jul 2009 22:16:41 +0100, "Graham." <m...@privacy.net> wrote:
>
> And on the subject of tube-neck magnets, I used to think "Blue Lateral"
> would
> be cool name for a pop group or mobile disco.
======================================
Terry Casey
Cl...@yewbank.demon.co.uk says...
Apologies! It was Max but I made a mess of the edit!
--
Terry
Clive
Casey <k.t...@example.invalid> writes
>Apologies! It was Max but I made a mess of the edit!
to think I might be trolling.
--
Clive
Terry Casey
Cl...@yewbank.demon.co.uk says...
You're very welcome! Unlike some others on here, if I make a mistake,
I'm happy to put my hand up and say so.
--
Terry
Graham.
>>
>>"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
>>news:u2q9m.59288$OO7....@text.news.virginmedia.com...
>>>
>>> Anyone remember ion traps on tube necks?
>>>
>>>
>>Not forgetting.. Raindrops on roses and whiskers on kittens, bright copper
>>kettles and warm woolen mittens, brown paper packages tied up with
>>strings..
> But not mentioning the ion trap magnets that stopped the dot in the middle
> of the face of the tube being burnt out, yes I remember them.
If I was a pedant I would say it was equally the electron gun assembly that
was aimed off-centre that prevented that.
The magnet deflected the electrons (but not the ions) back onto
the faceplate.
But I'm not, so I wont ;-)
--
Graham.
%Profound_observation%
Terry Casey
says...
>
> >>
> >>"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
> >>news:u2q9m.59288$OO7....@text.news.virginmedia.com...
> >>>
> >>> Anyone remember ion traps on tube necks?
> >>>
>
> > of the face of the tube being burnt out, yes I remember them.
>
> If I was a pedant I would say it was equally the electron gun assembly that
> was aimed off-centre that prevented that.
> The magnet deflected the electrons (but not the ions) back onto
> the faceplate.
> But I'm not, so I wont ;-)
The ion trap is not the same thing as the ion trap magnet!
The ion trap itself was the angled electron gun that fired off-centre:
see here: http://www.tuopeek.com/image2/e_gun1.jpg
The ion trap magnet was fitted over the electron gun to bend the
electron beam so that it hit the screen, as Graham said. The inertia of
the much heavier ions meant that they were deflected to a lesser extent
and landed harmlessly on the side of the gun.
Then someone added an aluminized layer behind the phosphor - probably
for its reflective purposes, as it increased screen brightness - but it
also stopped ions damaging the phosphor coating, so manufacturers went
back to straight guns and we no longer needed the magnets.
--
Terry