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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions. |
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15th Apr 2012, 7:39 pm | #21 |
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Re: PYE line-store standards converter
I'm delighted to say that I won the auction, and will be in touch with Malcolm presently to sort out the details. It will be on display from next year as part of our fledgling TV department, hopefully working at the Electrokinetica open day.
In the meantime I will keep it switched on 24/7 if that is what's best for it, noting Jeffrey's point about careful winding up and down as a possible alternative that reduces total run-time without causing thermal shock or electrical transients to components. I recall the last days of the CO6/501 in operation at Gerry's, also the contortions required to change diodes in the 625 commutator chassis, which might have been the last repair it had before the arrival of the CO6/509 digital. Gerry, Jeffrey and I went to pick it up and I spent the evening shuffling things around to fire it up inside the existing cabinet. Jeffrey then came over and organised the system rather more comprehensively. In fact the 501 had once worked quite well, I recall some almost stripe-free pictures in 1985 or 1986, perhaps after Brian Forster had spent some time on it. But the Lemco electrolytics especially were showing their age and starting to become a nuisance. Thanks to Jeffrey, Dave, Brian and others there has been a plentiful supply of 405 at Rosendale Road. I look forward to a similar supply (without the benefit of F TTL hardware multipliers) at Electrokinetica. If anyone wants to come and play it will be living in Hertfordshire at my store. Lucien |
15th Apr 2012, 7:59 pm | #22 |
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Re: PYE line-store standards converter
Well done Lucien.
I got the SPG which will be used as soon as its serviced. I was intending to bid on the converter but logistics took over. Our museum is well stocked but the converter would possibly have detracted from the museum, the other worry is the cost of running it 24/7. Good luck
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15th Apr 2012, 8:35 pm | #23 |
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Re: PYE line-store standards converter
Thanks Trevor, I hope the SPG turns out to be an easy job to sort out too.
Running a piece of electronic kit 24/7 isn't actually an issue for much of the year if it can be arranged to reduce the average heating load by the same amount. I always say that the best kind of electric heater is a dehumidifier, however at low temps you have to provide additional heat anyway to ensure the dehumidifier works properly and to prevent the kit itself getting too cold. A few thousand small collector loads can make a useful background heater! Once we have the broadband on, there might be a couple of webcams with live feeds to watch interesting pieces of kit on continuous power, tied into the security system. Streaming 405 is another interesting possibility... Lucien |
15th Apr 2012, 9:40 pm | #24 |
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Re: PYE line-store standards converter
Congratulations! It couldn't have gone to a better home.
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15th Apr 2012, 10:56 pm | #25 |
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Re: PYE line-store standards converter
Keep in touch Lucien and keep us all posted on the progress. I Intend to use the SPG to lock up a couple of 405 line cameras that I have fell heir too! I am awaiting their delivery. I certainly want to use the SPG with my PYE 405 line lynx initially.
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16th Apr 2012, 3:27 pm | #26 |
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Re: PYE line-store standards converter
Yes congratulations Lucien, I am so pleased it has gone to a good home. In my small way, if I can be of any help, please ask.
Trevor, I do have some circuits I could copy for the WG71 SPG if you need them? Brian S www.tvcameramuseum.org |
26th Jun 2012, 8:00 pm | #27 |
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Re: PYE line-store standards converter
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27th Jun 2012, 10:38 pm | #28 |
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Re: PYE line-store standards converter
Thanks Simon. That is very sad news. He was one of the great engineers who I found to be easy to get on with.
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28th Jun 2012, 9:20 pm | #29 |
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Re: PYE line-store standards converter
An interesting development...
I have recently been in touch with Paul Cox, who was at Pye TVT when the Line Store Standards Converter was being put into manufacture. Paul had some significant technical input to this project (and the later, more complex frame-store converter) and responsibility for the success of the rollout to the transmitter sites. Despite not having worked on one for nearly 40 years he has a clear recollection of the converter's circuitry and its foibles, which we discussed over a long phone call. Paul and I plan to meet up in the near future, when he has kindly agreed to talk me through the machine from his perspective. He had the job of giving lectures and preparing notes on it for training technical staff during the early days of manufacture, so this promises to be an informative and interesting meeting. He has also kindly offered a suitable Pye multi-standard monitor to go on the converter's shelf, which is something I was looking for. For now, I'll leave you with a picture of some of the dreaded ASZ20 transistors in one of the spare shift register units. There are six of these 16-stage registers in the converter distributing the read and write pulses to the groups of low speed switches in turn. The ASZ20 has rather a lot in common with the AF11x and not surprisingly many of these are duff. The shift registers actually in operation in the converter only began to function reliably once all 480 transistors were replaced! Lucien |
17th Sep 2013, 9:14 pm | #30 |
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Re: PYE line-store standards converter
Seem to remember a PYE converter when I worked for the BBC. Awful thing, full of germanium transistors which failed regularly.
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18th Sep 2013, 12:19 am | #31 |
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Re: PYE line-store standards converter
Hmm, I don't know that you can really blame the converter itself for the shortcomings of the transistors. The TO-7 package has been a real headache in every field of application and my impression (as I never maintained these in their heyday) is that many failures were of transistors in this package such as the shift register ASZ20s mentioned in the previous post. The sheer number of OC140s involved leads to a likelihood of having to replace some of those too, although I am not aware of them having been especially troublesome.
In the circumstances it was presumably the lesser of a number of evils. You can't make an all-electronic converter without a fairly high semiconductor count. The 'other' BBC converter design made exacting demands on its semiconductors, although it possibly used fewer. Or you are stuck with optical conversion and all its shortcomings. In any event, having had anything suspect carefully weeded out by its previous owner's thorough overhaul, my converter seems remarkably stable and reliable. BTW welcome to the forum! Please do post any more recollections you have about the converter! |
18th Sep 2013, 1:05 am | #32 |
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Re: PYE line-store standards converter
Ta. We are going back a few years. It was at Moel y Parc. I think it was replaced with a digital converter. Germanium transistors suffer far more with thermal runaway.
BTW, I had a 1953 TRF TV. I still have the wooden case and tube but I chucked the innards away. No-one seemed interested in it. |
19th Sep 2013, 12:12 am | #33 |
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Re: PYE line-store standards converter
Presumably the digital replacement was the excellent CO6/509. I would like one of those some day but need to get a few more TVs working first to justify it, seeing as I already have conversion capability +/- the odd vertical stripe.
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19th Sep 2013, 6:14 pm | #34 |
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Re: PYE line-store standards converter
I am struggling to remember what and who was where when Perhaps we didn't have one at Moel-y-Parc but a later device. Might have had one at Winter Hill or Holme Moss. Did we have Band III 405 BBC at Winter? I presume Moss covered most of the North on CH2.
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19th Sep 2013, 6:54 pm | #35 |
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Re: PYE line-store standards converter
Band III BBC... (Shudder)
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19th Sep 2013, 7:09 pm | #36 |
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Re: PYE line-store standards converter
Of course there was Band3 BBC at Winter Hill so that they could split the Northern Region.
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19th Sep 2013, 9:44 pm | #37 | |
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Re: PYE line-store standards converter
Quote:
Just an aside; but the logic of splitting the BBC North region in the way they did always baffled me. It was the Eastern half which suffered the worst of the continental interference ( being closer to the source of it! ) so why didn't they feed 'Leeds' to a new Band III Tx on Emley and leave Holme Moss to serve Manchester and North Wales? |
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19th Sep 2013, 10:01 pm | #38 |
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Re: PYE line-store standards converter
I know HM didn't serve parts of Lancs tucked close into the Pennines on FM so FM was added to Winter. TV would have been similar. Band I suffered with Sporadic E which caused interference all over Britain. We had relays in Wales which were useless for hours on end. Nothing you could do.
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20th Sep 2013, 10:55 am | #39 |
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Re: PYE line-store standards converter
Re: post no. 37
Possibly because in the NW Holme Moss TV aerials pointed toward the source of most SpE interference, whereas on the eastern side of the Pennines the receiving aerials had SpE in the back lobe (assuming they were not just dipoles). As a viewer in that area at that time I also remember that SpE from Spain was a problem, in which case you just had to live with it, as aerial sidelobe directivity was not great for 'H's or 'X's. |
20th Sep 2013, 11:12 am | #40 |
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Re: PYE line-store standards converter
On that basis then the Western side was more prone to Continental interference. I was told that HM did cause some probs on the near Continent during extended tropo due to its power and high overall aerial height. !979-80 was interesting for me when Americans hams were getting HM sound day after day via F layer. We would hear them on 50 MHz and we would reply on 28 MHz. I was at Crystal Palace for a while and they have pics and letters etc on the wall from DXers across the World who had have picked up CP during earlier sunspot maxima.
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