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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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12th Jul 2016, 11:03 am | #61 |
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Re: Earliest BBC2 Sets?
Nevertheless, the same valve UHF tuners must have been used in continental receivers so it is most likely they experienced the same reception problems as we did.
The early UHF tuners fitted in the Pye V700D and models 1,2, 3 and 11 were I believe made in Germany by R. E. Hopt. As John states the best valve UHF tuner was by far was the Philips unit. In America early UHF tuners employed a valve as local oscillator and a mixer diode. No RF amplifier. DFWB. |
12th Jul 2016, 11:50 am | #62 |
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Re: Earliest BBC2 Sets?
From the 1961-62 Radio and Television servicing book, page 23:
Apart from separate UHF tuners, some makers have developed special UHF "biscuits" which can be fitted to conventional VHF tuner units. These usually include a crystal diode as a harmonic generator, and other special circuitry. These "biscuits" would enable a Band I/III receiver to be converted fairly simply for UHF 405 line transmissions in areas of reasonable signal strength. DFWB. |
12th Jul 2016, 11:55 am | #63 |
Nonode
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Re: Earliest BBC2 Sets?
I wonder whether those early unsatisfactory valve UHF front ends were simply underspecified, perhaps overoptimistic on the signal level to be expected from the aerials/feeders of the day.
Or did the designers/production engineers just not manage to meet spec and had to give up? Martin
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12th Jul 2016, 12:24 pm | #64 |
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Re: Earliest BBC2 Sets?
Well the UHF tuners used in UK and Continental receivers were more complex compared to the early American tuners which omitted the RF amplifier stage.
Local oscillator radiation must have been a problem. DFWB. |
12th Jul 2016, 12:53 pm | #65 |
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Re: Earliest BBC2 Sets?
A RCA designed VHF/UHF tuner from 1953 is described in an RCA publication, page 318.
http://www.americanradiohistory.com/...-1953-Sept.pdf |
12th Jul 2016, 3:08 pm | #66 |
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Re: Earliest BBC2 Sets?
I guess that, with the strictly limited RF and mixer gain available from those early UHF front ends, more IF gain would have been desirable, but maybe that was just unaffordable in a dual standard set.
Martin
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12th Jul 2016, 5:26 pm | #67 |
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Re: Earliest BBC2 Sets?
The USA all channel act 1962 stipulated that all TV's should be capable of both UHF and VHF reception, with a noise factor of 14db max. That is probably how some got away with a biscuit in the VHF turret tuner for one channel UHF reception.
I cannot find confirmation but I understand that the UK band plan was drawn up with expectation of sets with a maximum noise factor of 8db obtainable with the components available at that time. Perhaps Philips tuners were the only ones that had that performance, the 8db was not mandatory. We were fortunate in my area that we were close to Winter Hill with few bad locations so usually the valve tuners worked ok, that and the small number of people who wanted BBC2 helped. Winter Hill went live in 1965 and within 12 months we had the better transistor tuners fitted in new sets. I did not convert any TV's to receive UHF that required more than just a tuner. The age of the sets, costs involved and program content put my customers off. Frank |
12th Jul 2016, 5:29 pm | #68 |
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Re: Earliest BBC2 Sets?
I guess the usual penny pinching was the reason why most of the early dual standard TVs had insufficient IF amplifier gain. Most manufactures hoped they'd get away with taking the output from the UHF tuner and feeding it into a two stage amplifier. Later on more IF gain was available by using the mixer valve of the VHF tuner.
At least Bush got it right with their TV125 model. The 1964 model TV135 which has the transistorized IF amplifier panel was particularly impressive. The early BBC2 sets that interest me are convertible models. There was many wonderful conversion contraptions created. Anyone own a converted Thorn 700 or 800 series receiver? DFWB. |
12th Jul 2016, 5:39 pm | #69 | |
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Re: Earliest BBC2 Sets?
Quote:
UHF local oscillator stability couldn't have been very good. Thank goodness such horrors didn't appear in our TV sets. DFWB. |
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12th Jul 2016, 5:39 pm | #70 |
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Re: Earliest BBC2 Sets?
I thought the TV135 and TV135R were 1966 sets, the two models one all valve although some had a transistor UHF tuner fitted and the Hybrid with the RF/IF stages being transistor the power stages valve. That was indeed a set the had an excellent picture and very reliable. We put those out and generally saw them 4 or 5 years later for the odd valve. The R model at around £10 cheaper was not in the same class, for either picture or reliability.
Frank |
12th Jul 2016, 5:49 pm | #71 |
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Re: Earliest BBC2 Sets?
Hi Frank,
I might have got the intro date wrong for the TV135 transistor IF panel model, but I'm thinking about the Bush set that employed the earliest 19" Mullard "Panorama" CRT. I do know that the A47-11W was made available to manufactures in 1964. DFWB. |
12th Jul 2016, 6:02 pm | #72 |
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Re: Earliest BBC2 Sets?
We were selling the new TV125's in 1965, I know that date due to changing jobs in February 1965. I am pretty sure the 135 series was a 1966 set although it could have been out for 1965 Autumn/Christmas.
The CRT's being made avaiable in 1964 could well be a Autumn/Christmas 1965 launch, time required to design cabinets and by that time put a new chassis in. At least the layout and fitting of the 135 chassis had not changed a lot since the TV105. It's a long time ago so dates tend to merge so I could be out by quite a bit. I will see what I can find in WW. Frank |
12th Jul 2016, 6:07 pm | #73 |
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Re: Earliest BBC2 Sets?
Seem to remember that Fred Dawes had the TV135 in stock circa 1965 when I worked at there main service department just off London Road, Manchester.
Lawrence. |
12th Jul 2016, 6:10 pm | #74 |
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Re: Earliest BBC2 Sets?
Well here it is, look like we were both out by a year, WW Oct 1965.
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12th Jul 2016, 6:12 pm | #75 |
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Re: Earliest BBC2 Sets?
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12th Jul 2016, 6:17 pm | #76 |
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Re: Earliest BBC2 Sets?
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12th Jul 2016, 6:23 pm | #77 |
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Re: Earliest BBC2 Sets?
In the same WW Oct 65 is a photo of Pye's first hybrid, the IF strip on the back of the 6 push button tuner. This is the 16 inch version but they used the same setup in the large screen sets.
I think the kindest thing I can say is that " I did not like them" Frank |
12th Jul 2016, 6:28 pm | #78 |
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Re: Earliest BBC2 Sets?
[QUOTE=Nuvistor;862952]There were several floors, I was mainly on the third floor doing chargeable stuff (Paid Service) Up near the top of the building was the CRT regun plant.
The basement was white goods repairs, stores and service control was on the ground floor, they had compressed air tubes for communication from the different floors down to the stores, the spares required were sent up in a small service lift. After a while I got a transfer to their service dept at Hale near Altrincham as it was closer to home. Lawrence. |
12th Jul 2016, 6:33 pm | #79 |
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Re: Earliest BBC2 Sets?
I did not know about the service dept in Hale, worked from an office in Hale, early 80's to late 90's. Any memories whereabouts in Hale?
Frank |
12th Jul 2016, 6:44 pm | #80 |
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Re: Earliest BBC2 Sets?
From Radio Electronics Jan 1962 is a photo of the Zenith Tuner with provision for 4 UHF strips. I would have thought that the performance was not that good, but would be interesting to know anyone who had experience of them. You never know they may have shown up our PC88/PC86 tuners, but not likely.
Frank |