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24th Mar 2017, 1:02 pm | #1 |
Dekatron
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Baird v. EMI
There are quite a few EMI first generation sets in working order. Perhaps fewer Baird T5s and T23s. The Bairds had larger screens but which gave the best viewing experience?
There are EMI sets that display 3 MHz bars. Do we have any Bairds with comparable performance or were they only capable to 240 line bandwidth? Peter |
24th Mar 2017, 2:48 pm | #2 |
Heptode
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Re: Baird v. EMI
Hi Peter,
I restored a T5 for a friend many years ago. It had the original CRT and the pictures were amazing. I would say it knocked spots off the 12" EMI sets and that is quite a claim for me to make. I will look out some photos when I get back tonight, however they don't do it justice because back then my digital camera was fairly low res. Note that the T5 was a superhet. The TRF T23 might not be as good, but then maybe Fernseh can see what his T23 is capable of? Maybe one day I will get the chance to meet up with the owner of the T5 again and take some fresh photos... Cheers Andy
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24th Mar 2017, 3:50 pm | #3 |
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Re: Baird v. EMI
Thanks Andy,
There are many who think of this period in TV history as primitive when in fact (in Britain at least) this was not the case but we need to display more of what was really available from this period. Let's publicse the evidence of world beating performance. Kind regards, Peter Last edited by peter_scott; 24th Mar 2017 at 3:59 pm. |
24th Mar 2017, 6:36 pm | #4 |
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Re: Baird v. EMI
In terms of build quality the EMI sets were far better than those made by the Baird company. Whereas the early EMI receivers were TRF the Baird sets were superhets operating at a very low IF. I don't know what the actual IF frequencies were but they were low which means the full vision bandwidth can be difficult to achieve. The Baird T5 had the advantage of having a great big 15" CRT. Wasn't the Baird T5 cheaper than the HMV 901 which had a 12" CRT? although it must be agreed the HMV and Marconi sets had much better cabinets. Actually the Baird sets were easier to service.
So to sum up EMI had the much better transmission standard but Baird might have had the edge on offering value for money TV receivers. DFWB. |
24th Mar 2017, 6:45 pm | #5 | |
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Re: Baird v. EMI
Quote:
DFWB. |
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24th Mar 2017, 6:48 pm | #6 |
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Re: Baird v. EMI
I'm jealous of what Jac has achieved on his Marconi 702 (even with a poor CRT) but I'd love to see what is the best Test Card C can be achieved on your T23 or 137T David.
Peter Last edited by peter_scott; 24th Mar 2017 at 7:14 pm. |
24th Mar 2017, 7:39 pm | #7 |
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Re: Baird v. EMI
Hi Peter,
The T23 is a TRF receiver so it should be possible to achieve full 3Mhz vision IF response without too much difficulty. I'm not sure how the receiver is aligned, it might be double sideband which means a full 6Mc/s bandwidth which means a lot of gain will be lost as a trade off for picture quality. What is required is the alignment details of the model T20 which uses the same RF unit. Of course it's possible that the TRF unit is aligned to one sideband only and a vestige of the other. Nevertheless, I reckon a much better picture is now possible with my T23 now that a really good CRT has been found for it. DFWB. |
24th Mar 2017, 10:41 pm | #8 |
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Re: Baird v. EMI
David,
It would be great if you can achieve it on the T23. Let's see 405 as designed in the mid 1930s. Peter |
24th Mar 2017, 11:04 pm | #9 |
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Re: Baird v. EMI
This is a subject that interests many of us in the NBTVA. Here are some observations:
The EMI system had 360 or so displayable lines - many more than Baird's 220 or so lines. But, if an EMI system TV wasn't interlacing properly (not uncommon) then it would have an effective 180 lines - I.e. less than Baird 240 line standard. The first thing you notice on a 240 line set (I know - I've made one!) is the flicker. Careful attention to brilliance and contrast can help minimise this. Also, the flicker is worst in peripheral vision. When you look straight at it, the flicker diminishes quite a bit. Hope this is of interest. |
24th Mar 2017, 11:25 pm | #10 | |
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Re: Baird v. EMI
Quote:
As can be seen from the untouched picture some work needs to be done to the TRF unit to improve the definition, the receiver resolves the 2Mc/s bars OK. I'm sure the of the RF unit can be improved on. DFWB. |
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24th Mar 2017, 11:33 pm | #11 |
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Re: Baird v. EMI
Hi Karen,
Vertical definition is important but I was more excited in this thread by the horizontal definition achieved by mid 1930s sets. Go for it David. Don't let Andy's description be the only defence of Baird's (or is that Bush's) reputation? Peter Last edited by peter_scott; 25th Mar 2017 at 12:03 am. |
25th Mar 2017, 12:06 am | #12 |
Heptode
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Re: Baird v. EMI
Hi All,
Here are the T5 photos as promised. They are not very clear and the program that was being received had some sort of faded/mixed pictures going on. I reckon that if the picture had been shifted of the top of the screen then I could have illuminated those lovely phosphor streaks at the back. However I found it a challenge to fill the mask without the 41MP timebase output triodes flashing over. Btw. This T5 (caps dated September 1936) has a unique dark cabinet finish and fluted doors over the controls at the front. It was originally dual standard, but the service info I have has had the relevant parts removed from the diagram. Tell tale marks on the timbase chassis show where extra 'factory preset' coarse timebase frequency controls were fitted and where a change over switch would have gone (probably a rotary one). There was no extra valve as in the EMI sets. Cheers Andy
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25th Mar 2017, 12:26 am | #13 |
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Re: Baird v. EMI
Thanks Andy,
That does look really good. Peter |
25th Mar 2017, 10:20 am | #14 |
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Re: Baird v. EMI
The Baird T5 together with all pre war Baird television receivers [from 1936] was actually a rebadged BUSH.
I have no doubt that the Bush produced T5 was a much better receiver than the EMI. The HMV and Marconi models used practically obsolete valves in the receiver section [MSP4s] and was a TRF design. I don't think MOV had valves stable enough to operate the local oscillator in a superhet. The EHT transformer in the Bush chassis was also vastly superior to the EMI. The Mullard TSP4 was built for the job. John. Last edited by Heatercathodeshort; 25th Mar 2017 at 10:35 am. |
25th Mar 2017, 10:59 am | #15 |
Heptode
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Re: Baird v. EMI
Interesting subject Peter.
I'm also interested in what David can get out of the Baird. There is also little known about the actual resolution of the 1936 transmissions themselves. Perhaps the end result of the Emicons through the whole transmitting chain did not resolve much about 2 MHz?? Specifications are not coherent and sometimes you read about 2.5 MHz. But who knows what practically could be achieved? There must be screen photos in publications to give an indication. The CRT itself also certainly diminishes the resolution. I can imagine that an excellent EMI 12" or 15" Baird tube can give very good result. Perhaps the 15" might have a slight advantage here... Jac |
25th Mar 2017, 12:47 pm | #16 |
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Re: Baird v. EMI
I have just received from a colleague, an interesting spreadsheet from an issue of the Royal Television Society publication current at the time we are talking about. It makes for interesting reading, especially as it does mention manufacturers using slightly coloured phosphors. Baird, or should I say Bush, does come out extremely well however who designed the sets? Was it Bush engineers or Baird employees because it seems as though they produced some really good pictures.
Mechanically, it's very difficult to judge between the two as they use completely different philosophies in their approach. The EMI school of TV manufacture starts with the cabinet maker and his veneering skills. From what I can see of the Baird school, this interest was dropped very early on as the cabinets simplified quite considerably when getting to the table models (marketing?) whereas the EMI versions (5" and 7") still had the cabinetmakers stamp on it. Anyway, the spreadsheet does make for interesting reading. |
25th Mar 2017, 1:15 pm | #17 |
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Re: Baird v. EMI
Thanks Brian,
That does make interesting reading. Although unfortunate that there is no comment against the T5c. There are some glowing remarks and a few critical ones. I guess the absence of a comment just indicates normality. I see the T5c was priced at 47 gns as against EMI charging 60 gns. It's surprising that there appear to be fewer T5/T23s surviving than there are 702/901s. Peter |
25th Mar 2017, 8:31 pm | #18 |
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Re: Baird v. EMI
Fascinating to see that there were so many television models available in 1937 with the service having only started the year before. One wonders how many sets were actually in service when the War broke out and everything was suspended.
Peter |
25th Mar 2017, 9:15 pm | #19 |
Nonode
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Re: Baird v. EMI
I remember seeing a Baird T5 in action at the Science Museum exhibition in 1980 and was very impressed by the picture.
As for Karen's comparison of 405-lines (rendered non-interlaced) with 240-lines (native non-interlaced), I attach two diagrams. The active line counts look like they are 188 (405) and 220 (for 240). There may be have been variations on this... the historians here may like to comment. Certainly, the 240-line demonstration at AP recently (courtesy the BVWS) was impressive. The 240-line picture looked subjectively sharper than the 405-line one to me. As Karen says, the flicker was immediately noticeable. I too have made a 240-line set. However this 'cheats'! It is an Argus with a fairly subdued CV2810 tube that has significant lag. So no flicker there... Steve
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26th Mar 2017, 10:08 am | #20 |
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Re: Baird v. EMI
Looking further into set pricing:
It strikes me as strange that the Baird T5c is priced as low as 47 gns. In the August 1937 edition of Television & Short Wave World the Baird advert also quotes the price of the T5 as 55 gns. Were they struggling to sell the T5 and T5c. Perhaps all the television manufacturers were struggling at this time. From various sources there were by the outbreak of the war something like 18,000 sets (perhaps not all in the hands of customers) but in the October 15th edition of Wireless World 1937 there is a report from David Sarnoff, president of RCA on his visit to Radiolympia. He states that fewer than 100 television sets were sold during the show and that fewer than 2000 sets have been sold since the start of the television service and of those 2000 less than half were in the hands of the public. Peter |