Memories - old technology

Remember trying to improve an old TV by adjusting the Convergenece Controls. I recall, my old Murphy had about 20 potentiometers and other ajustements.

Reply to
DerbyBorn
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Probably lots of them conveniently close to tingly high voltage bits.

I remember when all the 2ps we'd saved for the telephone became useless as the telephone got changed to 5ps and 10ps. (This was of course the telephone box down the road -- we didn't have one in the house.)

And being told to put the radio on at 5 to 1 for the 1 o'clock news - it needed time to 'warm up'.

Owain

Reply to
spuorgelgoog

Yes some of the ladies we had at rediffusion in Chessington could do purity static and dynamic convergence on a set in about three minutes. I really still don't know how they did it. Seriously though. I think the secret is doing things in the correct order or you muck it up.

Brian

Reply to
Brian Gaff

I have a Rogers Amp on my computer like that. Four ecl 86s need a bit of time to get their acts together.

Brian

Reply to
Brian Gaff

In message , snipped-for-privacy@gowanhill.com writes

10 to 1, otherwise you'd miss the shipping forecast :-)
Reply to
Graeme

I used to be expert at that, and colour adjustment. The TV firm I worked for had an exhibition display of about 9 sets stacked as a pyramid in the London Hilton Hotel. Out of our factory they were all wildly different, but I was able to make them look the same at first glance. Outside the open door was a line of Americans queuing for something else, and a couple of them came in saying they'd never seen anything like it - how is it done? - is there secret equipment in the roof? The poor souls had only had experience of NTSC in the US, "Never Twice The Same Colour", unlike our PAL, although the main reason in both countries was just shoddy adjustment and component drift.

Reply to
Dave W

Many of our 'radios' (internet, etc.) take just as long to start up. Give me a 'tranny' any day.

Reply to
Chris Green

I used to service valve 'scopes (Marconi Instruments and Tektronix), these had delay lines between the final valves of the amplifers and the tube deflection plates so that one could see the rising edge of a pulse that had triggered the scan.

The delay lines had to be 'tuned', there were 20 or 30 trimmers at least, you trimmed them for minimum distortion of a 'good' square wave at the front edge. Took ages!

Reply to
Chris Green

The main problem with NTSC was multipath propagation and reflections in distributed systems.

Reply to
Capitol

I moved on to using a series bus by 2000.

Reply to
Capitol

those problems were not unique to NTSC

Reply to
charles

I think the thing about crts was that since the controls were all basically either magnets or waveforms fed to the scan coils, one always affected another. You cannot really screen one electon beam and only control that one. The shadow mask was of course fixed and one hoped the combined tolerances of all the parts agreed enough that only minor adjustments were in fact needed. the corners were always way out of course but apparently the eye never noticed that much.

Why it took so long to phase out the CRT I shall never know as it was obviously the week link in the chain. I suspect it was the complexity of driving such a flat screen display that only became feasible with large scale integration and digital processing. Brian

Reply to
Brian Gaff

Yes our first test sets were RCA ones with a pre decoder in them. Pretty naff there was a hue and a tintcontrol on the front. You could make it look really crazy with those.

I also had no idea that Bell and hwell sold tvs in the states till i saw some of the ones in our lab. Blimey I'm surprised GM did not sell one.

Brian

Reply to
Brian Gaff

One of the fun devices was an electtron gun tube rejuvenator. When one of the colours was so low emission it really needed a new tube ten mins on this gadget seems to make it last at least another 6 months! Brian

Reply to
Brian Gaff

Internet and DAB both take an age to get going. The big advantage of the simple AM/FM transistor radio is that it runs a long time on batteries.

Reply to
Martin Brown

I remember the trade shows in the late 60s. In 1967, Rank Bush Murphy had theirs in the Lancaster Hotel* in Lancaster Gate - it was also owned by Rank, of course!

They had a display of a large number of their first colour set (CTV25 - later known as 'The Burning Bush' for obvious reasons!) in three rows - probably about 6 or 8 in each tier.

They were displaying test card F when I first saw them and it was amazing to see how well set up they were. The black and white balance was perfect with not a trace or hint of colour on any of them. The colour reproduction of the centre portion was similarly identical on every set plus, of course, there were no convergence errors visible.

It must have been a wonderful job for someone to set them all up!

  • The weather was much like it's been recently and the air- con was working overtime - so much so that, if you were unlucky to stand in the wrong place you would get a shower of ice cold water down the back of the neck where it was condensing in the overhead pipework and dripping out of the vents in the low ceilings!

I moved on to the Pye Group exhibition in the Grosvenor House Hotel after that - what a contrast - light and airy and beautifully cool with no added surprises!

Reply to
Terry Casey

indeed

that has been done, but not in mass market sets. Early sequential colour systems involved doing that with a single gun tube.

I saw one that wasn't. A weird viewing experience.

never true

they weren't

it did when they were

cost.

Reply to
tabbypurr

magic eye valve radio....Mmmmmmmmmmm

Reply to
Jim GM4DHJ ...

as the advert SHOULD say.... if you love radio don't buy a DAB .......

Reply to
Jim GM4DHJ ...

I always thought it was the purple and green flashing makeup the US newscasters used. Later they clamped chroma for everything near flesh tones to surreal pale orange. Neither looked anything like realistic.

There was nothing much wrong with the NTSC standard itself - Japan used a variant of NTSC but implemented it very much better just like they did with RIAA equalisation on consumer phono pickups. PAL had the huge advantage that systematic phase shifts were automagically cancelled out.

Reply to
Martin Brown

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