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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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5th Mar 2011, 7:14 pm | #81 |
Dekatron
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Re: 240, 405 & 625
I agree on that last sentence
As a continental European however, I should add that we once had those different measuring systems as well. The Inch, foot and yard were almost universally used across Europe. So were the pound and ounce. In the Netherlands, the metric pound and ounce (500gr, 100gr) are still in use. At the same point in time those were introduced, someone saw it fit to redefine the inch (duim or thumb as it was called here) to 1cm. However everyone called it a centimeter so by now a duim is 2,54cm again, but seldomly used. |
6th Mar 2011, 12:54 am | #82 |
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Re: 240, 405 & 625
Hi Maarten,
I understand that in Holland an experimental 567 line system was tested after WW2. A development of the 405 line system? 405 = 9X9X5. 567 = 9X9X7. DFWB. |
6th Mar 2011, 3:31 am | #83 | |||||
Nonode
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Re: 240, 405 & 625
Quote:
Arjoll has also quoted the New Zealand case, which shows that there would have been enough channel space in the two bands to obtain two program national coverage using 7 MHz 625-line channels. Quote:
So one might reasonably conclude that had the UK chosen 625 lines been chosen in the late 1940s, the advent of ITV in 1955 would not have required the use of UHF channels in order to obtain national coverage. The BBC would probably have started using Band III channels around 1952, say when the Wenvoe (Cardiff) transmitter came on line, by which time the pertinent receiving technology was well-developed. Quote:
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Overall it seems to be difficult to find cogent technical/technology reasons that support the 1940s decision to retain 405 lines, or that at least point to major difficulties to achieving success with higher standards. At the time, I suspect that it was realized that something better would be needed in the future, but it may not have been clear just what that would be, and for example the adoption by France of the 819 line system could have clouded the issue somewhat, making 625 lines not an obvious good bet for the future. That 625 lines turned out to be the “Goldilocks” system, as noted by Jeffrey (ppppenguin) could not have been known at the time. But by 1954-55 it was surely apparent, so perhaps the criticism, such as may be justified, should be aimed more at those in authority who failed to “bite the bullet” at that time and start ITV on 625 lines. I don’t think that by then it could have reasonably been claimed then that future uncertainty pointed to retention of the status quo; it looked more like a case of postponing the tough decision for expediency reasons. Having ITV on 625 lines with BBC on 405 lines may have been seen as giving the new service a technical edge, but then the 405-line proponents have argued that it was adequate for the time and/or that the realizable differences were but minor, so would that have been a material issue? Cheers, |
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6th Mar 2011, 7:37 am | #84 | |
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Re: 240, 405 & 625
Quote:
Hedgehope (our local) and Te Aroha? I know that here a band I/III aerial was called a "TV3 Aerial" for quite a few years when people started having ch 1-3/6-8 aerials to replace the old band I (some still just ch 1) 3 element yagi which were common before. Those of course are now replaced by 1-3/4-11 aerials to pick up CUE (ch 5) and FOUR (ch 11)! |
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6th Mar 2011, 8:45 am | #85 | ||
Nonode
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Re: 240, 405 & 625
Quote:
Yes, I think that Channels 10 and 11 were freed up quite late on. Neither was in use when I left NZ in 1985. Quote:
Cheers, |
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6th Mar 2011, 9:55 am | #86 | |
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Re: 240, 405 & 625
Quote:
My initial thoughts on reading Synchrodyne's suggestion were not so much that ITV would appear to be technically superior but rather the reverse. Much has been written in this forum about the horrible grey images when BBC2 started up and I well remember this and the poor noise performance of the early UHF front ends. Whilst the initially poor technical qualities of 625 transmission may not have been known to policy makers in 1955 it will certainly have been apparent to ITV promoters that they would gain nothing from the installed base of television sets if they had opted for that route. Peter |
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6th Mar 2011, 10:33 am | #87 |
Nonode
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Re: 240, 405 & 625
But I don't think that the "grey pictures" phenomenon was inherent with 625 lines. Rather that was simply the result of poor implementation. Certainly I don't recall anything grey about the New Zealand 625 line TV pictures. But then NZ monochrome valve receivers of the 1960s probably owed more to European and perhaps North American techniques than to British techniques. Thus it was normal for IF strips to have 3 frame grid stages (e.g. 1 x EF183 and 2 x EF184), as it was to have line and/or noise-gated black level agc, and fully isolated power supplies. Often the RF agc takeover point control was reasonably accessible, as well. Although this NZ expereince was at VHF, not UHF, during the early years good fringe area reception was a key factor, hence adequate gain and good agc. The main centre transmitters were not increased from 10 kW to 100 kW erp until around 1964, so signal strengths tended to be low even fairly close-in during the early days.
In fact the most common picture fault, or really picture fault setting that one saw was the "soot and whitewash" effect caused by black level being too low (brightness set too high) and the white level being set too high (contrast set too high). Typically regulation wasn't as good as it could have been, so that there was some black level droop as the contrast was wound up. Thus the poor impression of 625 lines performance in the UK was evidently caused by poor receiver design, such as the use of mean level agc and possibly inadequate overall gain. UHF didn't help, but with adequate gain and good black level agc amongst others, lower signal strength should have resulted in noisier but not greyer pictures. The techniques required to do better were readily available from the worldwide 625-line exprience, and by 1962 UHF reception was hardly new. It seems that by and large the UK industry ignored the worldwide experience. By the way, in sugesting that ITV might have started on 625 lines, I was assuming that the setmakers - or some of them anyway - would have done a better job in 1955 than they did with the coming of BBC2. Cheers, |
6th Mar 2011, 10:38 am | #88 | |||
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Re: 240, 405 & 625
Quote:
I understand that Mid Dome was looked over for Southland for similar reasons - it would have caused too many problems with channel coordination in other areas. When our local trust engineered 100.0 up there for Life fm they had to consider possible interference to the same channel in Oamaru! Quote:
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My parents were ribbon until the early 90's - I even did an install at our flat in Dunedin using ribbon because it was cheaper! I upgraded my parents place to coax around 1991 I think. Ribbon directly onto the folded dipole, balun at the back of the TV, then switching to one of those horrible 'easy fit' baluns at the aerial when coax was installed. |
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6th Mar 2011, 11:10 am | #89 | |
Nonode
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Re: 240, 405 & 625
Quote:
In my youth I had the good fortune to spend the best part of a day at the Waiatarua (Auckland) transmitter site in 1964 when the upgraded 100 kW erp installation was under way. The Marconi-EMI senders were being installed in the new hall, along with Marconi quadrant radiators on the new 400 ft tower being built by Italian riggers. Meanwhile transmissions were maintained by the existing 10 kW erp installation using the old 90 ft tower that looked very much like a converted electricity transmission tower. Te Aroha was a relay, then still 1 kW erp I think, and monitored at Waiatarua using a 4 or 5 element Yagi and a standard domestic receiver, side-by-side with a similar receiver with a direct fed from the adjacent Auckland transmitter. Whilst some interference was visible on the Te Aroha picture, there was certainly no greying. At the time I was surprised that such good reception could be had at the distance; even though both sites were elevated, more so for Te Aroha, there was high country (Hunua) in between. Cheers, |
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6th Mar 2011, 3:29 pm | #90 |
Octode
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Re: 240, 405 & 625
I think commercially if you'd started ITV on 625 lines it would have been difficult to get companies to invest. They needed to get an audience quickly, this was possible with bolt-on tuners for old sets but would have been difficult if new expensive sets had been required. Remember who the target viewers of the commercial services were - i.e. working and lower-middle-class households.
Also, bear in mind that most people really don't give a monkeys about quality so long as something is "new"...the number of times I've had somebody proudly pointing out picture faults as details on new TV makes me want to weep! I have to say after all this I really can't see what better plan the government could have come up with, in the end prevarication was probably the correct course. After the war if I'd owned a pre-war TV and they restarted on a different format I'd have been mightily peeved - especially as I'd probably have been able to make a few bob out of the valves during the shortages. Also the BBC could more or less just start up - a big morale boost. Mucking around rebuilding transmitters, studios etc during a time of great privation would have been a slow, unpopular move likely to cause futher resentment. The move to 625 was not at all obvious at the time and the choice of a colour system not at all clear even after the fact...No wonder the BBC and ITV companies were pushing for 405/NTSC which must have seemed a no-brainer at the time. Dom |
6th Mar 2011, 4:39 pm | #91 |
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Re: 240, 405 & 625
Personally, I do not think there was any reason to think that "class" had anything to do with ITV. The BBC very much needed competition to improve its programming to be acceptable to a wide section of the public. The BBC sat very much on it's laurels up to the start of ITV, look at the success of Coronation Street from it's start in 1960, it's even a favourite with the Royal Family, everyone else is "lower Class" in comparison to HM's family!
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6th Mar 2011, 9:11 pm | #92 |
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Re: 240, 405 & 625
Well it did when in terms of advertising - in the 1950's the workers had the buying power. When you're selling soap powder, toothpaste etc numbers matter, nothing else, and that is probably what saved 405 lines for so long - it was the way to roll out more telly to more people.
This is easy to forget sometimes these days when the class system is a different kettle of fish but ITV had to appeal to as wide an audience as possible. When BBC2 came out on 625 lines it was definitely the very opposite in terms of the target demographic! Dom |
6th Mar 2011, 9:27 pm | #93 |
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Re: 240, 405 & 625
Very true.
The BBC though up to the start of ITV were stagnating and catered for a highbrow audience, they of course did this with BBC2 and the early take up of BBC2 was poor, so was this the program content that caused lack of interest or the cost of buying dual standard TV sets or even the lower than expected picture quality. When it comes down to class structure I shudder at it. My dad although a Aeronautical Design Draughtsman and clever was working class, my mother though was born to a high class family with her Dad having business's, loads of medals and an MBE, so we were brought up to treat everyone as equal. Sorry for being OT.
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6th Mar 2011, 11:21 pm | #94 |
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Re: 240, 405 & 625
Yes, using "class" in these contexts is quite difficult - and a very blunt tool - I've no idea where I fit in either! My point would probably be better made by saying lower income households.
Whatever the BBC were doing, switching to 625 lines for ITV would have been commercially unnatractive if most people could not or could not afford to receive it. It would then be an uphill struggle to coax people into buying new sets. However it does still interest me how many receivers are found from the early 50's that seem never to have been upgraded for ITV. Dom |
7th Mar 2011, 9:29 am | #95 |
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Re: 240, 405 & 625
The ITV converters were fitted across the board, with people from all walks in life wanting ITV, a good number would have the manufacturers tuners fitted too.
The cost would have been a converter, or a mod plus a band 3 aerial and either a new cable run or a diplexer, Quite expensive in the mid 50's but perhaps cheaper than a new set.
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20th Mar 2011, 8:08 am | #96 | |
Nonode
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Re: 240, 405 & 625
Quote:
Probably some of the numbers that would answer the above questions cannot not be deduced with any worthwhile accuracy, but it seems at least possible that within a few years of their initial availability, the number of 13-channel (as built) receivers in service easily exceeded the total number of Band I-only receivers. If that was the case, then easy access to the installed base would have been less of a reason not to start ITV on 625 lines. I have found some further comments on the subject in a BBC brochure “Engineering Division” published August 1961 as a supplement to Ariel magazine. To quote: “In Britain, the world pioneer of high-definition television, a 405-line standard was adopted in 1936 when the service was started and the Government accepted the recommendations of Lord Hankey’s Television Committee in 1945 that the service should reopen with the same standards after the war. It should be remembered that at that time the 625-line standard, since widely adopted in Europe, had not been put forward. (In 1948 the Government announced that the 405-line standard would also be used for further stations.)” The parenthetical part is interesting, as it implies that additional to the 1945 deliberations there was shortly afterwards another nodal point from which a different direction could have been taken, as by then the 625-line system was available. Or, it wasn’t automatic that the decision to reopen the London service on 405-lines implied that this standard would also be used for nationwide coverage. Conceivably there was debated the possibility that the UK could have followed the French pattern, that is retention of the established lower definition service in the capital but implementing a higher definition standard for nationwide coverage. Also from the same brochure: “..an investigation was made into the respective merits of television standards based on different numbers of lines; a full-scale experiment to compare the relative merits of the British 405-line system and the 625-line system widely used in Europe was carried out recently and involved the installation of an additional high-power transmitter at Crystal Palace operating in Band V..” Presumably this study informed the early 1960s TAC recommendation and the subsequent Pilkington Report. Cheers, |
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20th Mar 2011, 10:15 am | #97 | |
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Re: 240, 405 & 625
Quote:
Perhaps an alternative question would be 'When did Converters stop being made?' Alan |
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9th Apr 2011, 6:47 am | #98 | |
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Re: 240, 405 & 625
Quote:
Moving on to a more general look at the 405 and 625 line comparison, it would be interesting to know what were the reasons for selection of the CCIR 625-line standard in Australia and New Zealand. Both countries, perhaps more so New Zealand, were still much British-influenced in the 1950s. As far as I know both countries looked at 405 as well as 625 lines before making a decision. In New Zealand the initial TV service was established on a minimum-cost basis, so 405-line system could have been attractive in that sense. Insofar as for many years TV receivers were locally manufactured by what was essentially a protected industry, then a choice of 405 lines might have made receivers just a little lower in cost, but in any event there was no need to worry about whether or not standard models from overseas would work. Most program material from overseas – a lot of it from the USA - came in film form so there were no compatibility issues to worry about there. Against that background, it is not unreasonable to assume that the choice of 625 over 405 lines was made for fairly compelling technical and performance reasons, notwithstanding the potentially lower cost of 405 lines. Typical receiver screen size might have been a factor. In the early monochrome days 23 inch was the popular size. But whether or not that would have been predicted during the standards deliberations is hard to say. Cheers, |
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10th Apr 2011, 11:20 am | #99 |
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Re: 240, 405 & 625
Using 405 in 1946 was probably correct and obvious choice.
But (re-)starting TV at all before 1948 or 1950 was probably wrong. If TV had been restarting in 1949 would it have been 405 or 625? More likely 625 with better option for UK makers (essentially similar model for export and domestic). Note in the recent ISDB-T vs DVB-T debacle in South Africa, the local manufacturers wanted the wider DVB-T standard, and NOT a local version (different channel width) of the Brazilian version of obsolete Japanese ISD so as to have better export profits. Ironically after years of 405/525/625/819 and PAL, PAL N, various SECAM, NTSC we have far MORE digital standards for SD and a huge number for HD instead of a single 48 fps 1154 line HD standard (to allow best Film transfer from 24fps). Originally Analogue HAD to be 30fps 60Hz in USA and 25fps 50Hz in Europe due to making any Hum bar relatively stationary. Interlaced 24fps 48Hz would have made more sense for Film compatibility. By Digital era frame conversion etc is working and PSUs are not an issue so having a single world wide 24fps based (maybe 48Hz or 72Hz refresh) single number of lines (600 SD, 1154 HD?) would have been possible. In 1946 the 625 was still too embryonic, though Germans had used HD CCTV on rocket ranges and Russains doing 625 line tests. If UK had waited till 1949, (and many, many countries didn't have TV till later and not all of UK by any means had TV by 1950), then 625 would have been a better choice. I don't believe the 15.625KHz Line frequency LOPT was a real issue, even with laminated rather than ferrite construction. It has advantage that much fewer people hear the Line Whistle than the quite obvious 10.125KHz whistle on many 405 line sets. 405 Colour was never viable. Colour had been demonstrated as long as 1924 I think and was an inevitable development. From that point of view a 405 system was always going to be obsolete sooner rather than later. Widescreen is another example of a technology too soon (like TV in 1946). It would have been better to not have WS TVs at all till HD was available as it actually degraded analogue (16:9 cropped and resampled into 4:3 frame, in 4:3, 14:9 or 16:9 format) and is reduced horizontal resolution for same height of screen and degraded 4:3 images on WS CRTs. Obviously people never learn, introduce technologies a couple of years too soon and without enough thought. I remember the start of BBC2 on 625 just outside Belfast. As kids we sat and watched the test transmissions. We were impressed by the extra quality on our dual standard TV. On UHF it had continuous tuning and a scale rather than fixed channel selections. During the 1970s when still a school kid I repaired many Dual standard sets by soldering the switch in the 625 position. After BBC & UTV added to 625 lines I don't remember anyone sticking with 405 line on Dual standard sets. I did repair a number of 405 only sets too in the 1970s. These where invariably used as 2nd or 3rd sets. Some I got for nothing and sold cheap after repair. Usually faulty Dropper resistors, or mains rectifier or a valve. The big wooden cabinets on some (but some 625 only sets had big wooden cabinets) gave nice audio. I remember one 405 set with corded remote and motor drive on channel change and a couple with FM Radio. I never remember any dual standard or 625 only sets with FM Radio or Remote up till about 1976 when I stopped fixing TVs. The first non-cable remotes I saw where on early Betamax and VHS machines, but 2nd stage electronic control panels rather than purely mechanical controls as on first models. Last edited by neon indicator; 10th Apr 2011 at 11:26 am. |
10th Apr 2011, 12:15 pm | #100 |
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Re: 240, 405 & 625
During the war Britain's radio industry was totally occupied supplying the needs of conflict. The loss of war contracts in 1945 would have left a very large hole with next to nothing to fill it if we had delayed television restart until 1949 or '50.
The nation was on its knees and the promotion of the idea that Britain still leads the world in technology was important to general morale. It seems to me that restarting 405 was the correct decision. Again, with widescreen, seen from a set manufacturers point of view you need to be introducing some new gimmick every now and then just to promote new sales. Peter Last edited by peter_scott; 10th Apr 2011 at 12:23 pm. |