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Old 16th Dec 2015, 4:36 pm   #301
SteveCG
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Default Re: 405-Line VHF Aerials 2013 to the present day.

ORTF - post no. 300

Another interesting design. I notice that you suffer in France, as well as here in the UK, from the 'missing element' effect!
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Old 17th Dec 2015, 3:52 am   #302
Synchrodyne
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Particularly with the low-channel and wideband Band I aerials, with their relatively long elements, I wonder if there is any evidence that the vertically oriented examples are more durable than their horizontally oriented counterparts. It seems possible that the cantilever load on the horizontal element mountings might be an “early” (relatively speaking) failure point. In this part of New Zealand (Bay of Plenty), redundant vertical Band I arrays still abound. The oldest of these would be no earlier than the mid-1970s though, when TV2 started transmission on channel NZ3, and wideband arrays largely replaced the previous single-channel (NZ1) arrays, although occasionally one sees an example of the latter. It is purely a qualitative observation, but these vertical Band I aerials seem to be more numerous, relative to the number of dwellings, than horizontal Band I aerials in other parts of the country.

Thanks to ORTF & Co for the interesting information about French TV history and TV aerials. An item in Wireless World (WW) for 1962 October (p.482) about the opening of the ITA Fremont Point transmitter in Jersey also included the following comment: “It is understood that there are some 2,000 dual-standard (405/819 lines) sets in use along the Coast of the Havre peninsular, where viewers get a reasonable signal from the B.B.C. station on the island. The I.T.A. station will, in fact, radiate a daily French news bulletin (intended primarily for the French-speaking section of the island’s population) and include some French manufacturers amongst its advertisers.”

So it’s a reasonable assumption that those French viewers who had dual-standard 405/819 receivers probably had rooftop VHF Band I and/or Band III aerials that were actually used to receive 405-line transmissions. I wonder though whether BBC Les Platons channel B1 (H) would have been subject to interference from ORTF Caens on channel F2 (H). I can’t recall what the intervening topography was like, although my recollection is that it was not flat looking westish from Bayeux.

France seems to have had a history of using multistandard TV receivers for regions where cross-border transmissions were receivable. There is mention of the “Strasbourg” type 625/819 receiver in WW 1954 June (p.263) and again in 1954 July (p.324); this appears to be similar in concept to the Belgian four-system receivers used from the start in that country. Evidently this multistandard concept was extended to 405/625/819 receivers, judging by this comment in WW 1959 October (p.456), in a report on that year’s Paris Radio Show: “In certain parts of France reception of television programmes from other countries is possible. However, since these programmes have different characteristics, multi-standard sets have to be provided to receive them. Among the numbers of such receivers on show we saw one, the Telemaster Super V5D FM, which could receive as many as five types of television transmissions-819 lines on French and Belgian standards, 625 lines on Belgian and European standards and even our own familiar 405 lines—not to mention f.m. sound broadcasts in Band II.” (As an aside, the same paragraph in that WW article also mentioned the ‘décodeur bilingue’ required for the French North African TV broadcasts with bilingual sound using a TDM system; the first non-experimental use of multiplex in broadcasting, I think.)

There was further mention of 405-capable French TV receivers in the WW 1965 October (p.501) report on the 1965 Paris radio Show: “The multi-standard television receiver for use in frontier areas is, of course, a familiar object at European radio shows and at Paris most of the larger manufacturers had two or three sets in their normal range. Several of the French-made sets will receive the French (14 Mc/s), Belgian (7 Mc/s) and Luxembourg (7 Mc/s) 819-line transmissions on v.h.f., the French 625-line second programme on u.h.f., the Belgian 625-line transmissions on v.h.f., and the European (7 Mc/s, f.m. sound) 625-line broadcasts on v.h.f. from Germany, Switzerland, Italy and Spain. British 405-line pictures can be received on some sets made by Grammont. Apart from all the complex circuitry and switching needed for multi-standard reception, a fairly elaborate aerial system is usually required as well. The old method of turning a handle to rotate the aerial to receive a required station has now been superseded by the remotely controlled electric drive, comprising a motor mounted half-way up the mast and a control box (providing aerial position indication) in the living-room. Belvu were showing a whole range of these controlled drives at prices from about £30 to £150.” Presumably adequate UK 405-line reception was possible at some locations along part of the “top left” perimeter of the hexagon (say Cherbourg to Calais) to justify the availability of the multistandard receivers with 405-line capability and “405” aerial systems.

But even before the Strasbourg type TV receiver arrived, there were evidently some dual-standard 441/819 examples. From the WW 1951 November (p.459) report on the Paris TV Show: “Altogether 81 different receivers were shown. Most exhibitors had a standard chassis in different cabinets - some of these incorporated a broadcast receiver or a record changer, and others were for long-distance reception with one or two r.f. pre¬amplifier valves. Seventy per cent of the sets were for the high-definition 819-line standard and included six dual-standard 441/819-line receivers. The number of valves varied between 15 and 22 for 441 lines and between 14 and 23 for 819 lines.”

So Parisian viewers of the time who had dual-standard 441/819 receivers might have had aerials for both channel F1 (V) and F8A (H). Since such viewers would not have had to change receivers and aerials at the cessation of 441-line broadcasts, just maybe there is an outside chance that an F1 (V) aerial somewhere did survive.

Cheers,
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Old 17th Dec 2015, 11:48 am   #303
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My experience of aerials agrees with Synchrodyne's observation that Band I V. Pol aerials tended to keep their elements for longer. No always though. There are articles in Wireless World in the late 40s'/ early 50's talking about element failure due to wind resonance. To overcome this Belling and Lee put some string/cord inside their elements. The aerials shown were V. Pol aerials - but that might just have reflected the point that most of the early UK transmitters were V. Pol.


When it comes to H. Pol Band I aerials then channel B1 certainly comes to mind for snapped dipoles! Here the failure is usually that the insulated junction box cannot that the strain due to gravity acting on the dipole elements. A large crow landing or taking off on the end of the dipole element must have also added to the problem.

But not all makers used this form of connecting the dipole to the download. The multi element Band I aerials made by Telerection used the Delta match (and earlier ones the 'T' match) which meant the dipole was mounted with a solid metal bracket.

Also I've come across some 'cheapo' H. Pol designs (usually for use in the later relay service areas) that used 3/8 inch diameter aluminium for channel B2. More reputable makers used 1/2 inch diameter aluminium/aluminium alloy. Here it is the element that bent (and snapped) under its own weight - not the junction box failing.
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Old 19th Dec 2015, 10:35 am   #304
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Synchrodyne (and others) : sorry, my reply is rather long, but I tried to add as many details as possible to your questions or comments.

Quote:
Originally Posted by Synchrodyne View Post
(...)An item in Wireless World (WW) for 1962 October (p.482) about the opening of the ITA Fremont Point transmitter in Jersey also included the following comment: “It is understood that there are some 2,000 dual-standard (405/819 lines) sets in use along the Coast of the Havre peninsular, where viewers get a reasonable signal from the B.B.C. station on the island. (...)
In fact, it is not Le Havre, but Cherbourg peninsular. The B.B.C. was very much in advance with its transmitters commissionings, so that as soon as October 1955 Les Platons was already in service while the R.T.F. had still no transmitters in the West of France. At that time 405-819 dual-standard receivers were quite unknown, and anyway very expensive, so French authorities feared the same problem as in Strasbourg, where people began purchasing 625 lines System B TV sets because the R.T.F. was not yet received there.This is why Rouen and Caen transmitters were brought to service in 1956, and Rennes was planned for 1957. However financial restrictions forced the R.T.F. to delay it to 1959.

Quote:
(...) The I.T.A. station will, in fact, radiate a daily French news bulletin (intended primarily for the French-speaking section of the island’s population) and include some French manufacturers amongst its advertisers.”
I indeed remember in Ouest-France regional newspaper's Rennes edition in the Seventies, a small BBC-ITV programmes section showing 5 min 'Nouvelles en français' ('News in French') circa 10.35pm after 'Channel News and weather'. Because Nantes was far too much in the South, I never could see these news in French myself. I believe they disappeared in the Eighties, because there was no more BBC-ITV programmes in Ouest-France. Now otherwise, ITV Channel never airs any programme or news in French.

Quote:
So it’s a reasonable assumption that those French viewers who had dual-standard 405/819 receivers probably had rooftop VHF Band I and/or Band III aerials that were actually used to receive 405-line transmissions.
You are quite right indeed, Synchrodyne. I remember that when we had a trip in the Seventies along the coast of Northern-Brittany from Saint-Malo to Saint-Brieuc, we could see some Band Ih+IIIh aimed towards Jersey, in the cities quite exclusively - very few in the country, where English language was mostly unknown. Quite all of them were replaced after 1976 by UHF models (ch 41-44-47-51 H), despite the need of a rejector because of Rennes transmitter's too close channels (39-42-45 H). I guess this was probably because football fans could now appreciate British Leagues matches in colour, as multi-systems PAL-SECAM TV-sets were more common at that time than 405-819 lines sets in the Sixties.

Quote:
I wonder though whether BBC Les Platons channel B1 (H) would have been subject to interference from ORTF Caens on channel F2 (H). I can’t recall what the intervening topography was like (...)
Les Platons used channel B4-H, not B1-H that was used by Redruth. So there was absolutely no problem of interference from Caen Mont-Pinçon whose sound was on 41.25 MHz and video on 52.40 MHz, while Les Platons used higher frequencies : video on 61.75 MHz, audio on 58.25 MHz (almost 6 MHz away from Caen video frequency). Only possible interferences could have occurred on Caen from North Hessary Tor ch B2-V (audio, 51.75, video 48.25 MHz),and on Les Platons from Nantes Haute-Goulaine ch F4-V (audio 54.40 MHz, video 65.55 MHz) but both these transmitters used vertical polarization, which limited risks of long-distance interferences.

About that channels B4 and F4 frequencies spectrum, it is interesting to note that initially the R.T.F. had planned ch F4-H for Rennes Saint-Pern in its initial national network plan, 1954. However, the B.B.C. launched Les Platons first (in 1955) and the only channel available was ch B4 : North Hessary Tor used B2V, Rowridge B3-V, Redruth B1-H and Wenvoe, also received in the South-West, used ch B5-V. Consequently, the R.T.F. decided to use outband ch F5-H instead for Rennes, while ch F4-V was assigned to Nantes, about 200 km away from the Channel Islands.

That initial choice of channel F4-H for Rennes St-Pern, that would have resulted in overlaps with Caen Mont-Pinçon's channel F2-H, was rather surprising otherwise : it certainly would have resulted in interferences between both these transmitters using a same polarization, and only 2 MHz space between ch F2 video (52.40 MHz) and ch F4 audio (54.40 MHz). I perfectly remember that in Nantes, when I tuned from our ch F4 to ch F2, the sound was entering the video and we could see it 'moving' on the screen exactly in the same way as a UHF tuner tuned too far from the wanted channel, e.g. on ch 30 instead of ch 29. I think that the R.T.F. lately discovered that problem and thus did not oppose the B.B.C. using ch B4 in that zone, because it would not occupy so much spectrum and there would be no interferences with Caen's ch F2-H.

Quote:
France seems to have had a history of using multistandard TV receivers for regions where cross-border transmissions were receivable. There is mention of the “Strasbourg” type 625/819 receiver in WW 1954 June (p.263) and again in 1954 July (p.324); this appears to be similar in concept to the Belgian four-system receivers used from the start in that country (...)[/I].
Because of WW2, priority was given by the R.T.F. to rebuild its 90% destroyed LW-MW radio stations (Allouis LW launched in 1939, sabotaged by the Nazis, was only brought back to service in 1953). So Television was not a priority. It really took off with H.M. Queen Elizabeth's Coronation when in Strasbourg people could only watch it on German Baden-Baden transmitter. Meanwhile, neighbouring countries were launching - or developing - their TV networks too : 405 lines BBC (received from Dover, North Hessary Tor and Les Platons), the Belgian ch E8 819 lines French INR and ch E10 625 lines Flemish NIR transmissions from Wavre in the South of Brussels and Liege-Namur 819 lines ch E3 from 1956, Télé-Luxembourg radiating 819 lines ch E7 up to Reims, Epinal and Sedan from January 1955, German TV from Sarrebruck (after a short 819 lines low-power period when Saar was under French mandate until 1956 - from Baden-Baden and Freiburg, Swiss TV from Zürich and Geneve (whose 'La Dôle' ch E4-H had a wide receiving area in Alps and as far as towards Dijon in Burgundy - from 1956, Monaco 819 lines ch F10 from November 1954 on the French Riviera and in upper parts of Marseilles, and Italian RAI on the eastern parts of French Riviera and Corsica from 1954. Various audio and video characteristics of course progressively brought people towards 'multistandard' (multi-systems) TV-sets, while the R.T.F. tried to counter-attack in giving priority to regions receiving these foreign transmissions. Of course, this choice was much disappointing for people in the Middle and especially the South-West ('Midi') where no foreign transmissions were real competitors - Spanish TV received from Barcelona and San Sebastian on both Meditteranean and atlantic coasts, where only received in restricted areas.

Quote:
Among the numbers of such receivers on show we saw one, the Telemaster Super V5D FM, which could receive as many as five types of television transmissions-819 lines on French and Belgian standards, 625 lines on Belgian and European standards and even our own familiar 405 lines—not to mention f.m. sound broadcasts in Band II.”
I remember at the end of the Sixties, we visited a French Navy ship with my parents. We were kindly invited to have a drink in a room where they had a big TV-set with lots of buttons. I had seen a combined VHF-UHF aerial just above the metal door, that I surprised me a lot - I think it was in fact a multiband American one. When I asked if it could receive foreign transmissions, a sailor told me "everything in the world ! From America to... Russia !". He was not joking. I think this was the Telemaster you are talking about. That set had been modified, he told me, by one of the radio engineers aboard the ship. So it was able to receive -in black and white - any channel and audio/video system in the world.

Quote:
(As an aside, the same paragraph in that WW article also mentioned the ‘décodeur bilingue’ required for the French North African TV broadcasts with bilingual sound using a TDM system; the first non-experimental use of multiplex in broadcasting, I think.)
This system was designed by an engineer for the R.T.F. transmitter in Algiers so that some programmes could be broadcast in both French and Arabic languages. I could read in the blog of a former contributor to RTF Algiers, that for instance female announcers were presenting the programme in French and in Arabic every two weeks alternatively : the announcer who was not on the screen was translating on her own audio channel what her colleague was announcing in the other language on the screen. News and some variety shows were also translated live on these alternative audio channels. However this system disappeared in 1962 when R.T.F. was replaced by independent Algeria's own TV body, that although maintaining the existing System E 819 lines network, developped a fully 'nationwide' one with System B 625 lines. These dual-sound transmissions ceased with the independency. In France, they resumed with a totally different system (NICAM stereo and multilingual) with French-German network ARTE in... 1992.

Quote:
(...) Apart from all the complex circuitry and switching needed for multi-standard reception, a fairly elaborate aerial system is usually required as well. The old method of turning a handle to rotate the aerial to receive a required station has now been superseded by the remotely controlled electric drive, comprising a motor mounted half-way up the mast and a control box (providing aerial position indication) in the living-room. Belvu were showing a whole range of these controlled drives at prices from about £30 to £150.” [/I]Presumably adequate UK 405-line reception was possible at some locations along part of the “top left” perimeter of the hexagon (say Cherbourg to Calais) to justify the availability of the multistandard receivers with 405-line capability and “405” aerial systems.
In fact in France, except for DX-TV fans, people never really liked to 'play' rotating aerials. They usually preferred to have one aerial tuned to its specific transmitter, so that in Southern Alsace you could - ad still can - see : three Band III-h aerials and three UHF aerials aimed towards French local 'Belvédère' transmitter in Mulhouse, Swiss local transmitter near Basel, and German transmitter near Freiburg-in-Brisgau. Near Luxembourg you could see a Band Ih aerial and a UHF one aimed towards Sarrebruck (German TV), a band III-h and a UHF one towards Arlon (belgian RTBF) and a similar set towards Dudelange (Luxembourg German, French and Belgian networks), and a III-v (formerly outband III-h) and UHF set towards French transmitter in 'Luttange' near Metz.
Of course, since DVB-T replaced analog TV, all VHF aerials are useless - except band III in Luxembourg - and many UHF obsolete aerials have been replaced by new models tuned to various specific channels.

Quote:
(...) Parisian viewers of the time who had dual-standard 441/819 receivers might have had aerials for both channel F1 (V) and F8A (H). Since such viewers would not have had to change receivers and aerials at the cessation of 441-line broadcasts, just maybe there is an outside chance that an F1 (V) aerial somewhere did survive.
Such dual-standards were extremely rare. In fact, because of its 30 kW power and its low frequencies, the 441 lines transmitter was far better received by specially designed 'long-distance' TV-sets than the 819 lines temporary low-power (8 kW ERP) transmitter installed atop Eiffel Tower. I am quite sure the I.T.A. in 1955 benefited from previous experience and tests by the R.T.F. and broadcasting equipments manufacturers : in 1949 when the 819 lines transmitter was launched, they were still unable to design and build aerials, but especially long feeders -e.g. 330 m for Eiffel Tower - able to convey high-power VHF without significant loss. The high-power transmitter could be only brought in service in 1954. Meanwhile, the R.T.F. tried to favour the development of this new 'national' service, thus limiting live transmissions and events to the 819 lines users. The 441 lines ones had then only some talk shows and old movies and felt abandoned until the standard conversion was designed and adjusted by common BBC-RTF studies for the 'Franco-British Week' in July 1952. A long-remanence 819 lines tube was used with a 405 or 441 lines camera respectively, whose optical focus was slightly modified to correct possible visual defaults when pointing to the screen. This system gave a rather satisfactory result until it could be replaced by totally electronic converters at the end of the Sixties.

Attachments :

1- A map in French 'Télé-Magazine' TV guide, January 1960 showing foreign TV's main reception areas in France. Captions specify the number of lines ('lignes') and the system used ('norme') with its EBU ref. letter.

2- A detail of this map for BBC Les Platons transmitter and its neighbouring French transmitters and frequencies/polarizations.

3- The estimated service area in Wireless World, August 1952, of the BBC's future Wenvoe transmitter on ch B5-V.

4- The first experimental standards converted used by the BBC in Cassel (between Lille and Boulogne) during the French-British week, July 1952, that can be considered as a kind of rehearsal of the future Coronation's European covering, June 1953.

5- The standards converter and its control equipments uased by the RTF in 1954 for its 441 lines transmitter. In the background, a special 819 lines long-remanence TV monitor facing a 441 lines camera equally adapted to avoid visual interferences during this optical conversion process.
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Last edited by ORTF_&_Co; 19th Dec 2015 at 11:02 am.
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Old 19th Dec 2015, 6:44 pm   #305
ORTF_&_Co
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Default Re: 405-Line VHF Aerials 2013 to the present day.

About VHF bands I & III combined aerials, this interesting article illustrated in Wireless World, October 1959 :
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Old 21st Dec 2015, 11:07 am   #306
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Re post no. 305

Pic 3 - For your info: The straight rods are reflectors in that design. It was also sold with a Band I "dipole" (one of whose elements was adjustable in length to suit the local V. Pol Band I transmission) as a loft aerial that covered all the UK TV channels. The combined was a V. Pol only design. The picture shows the physical set-up to receive V. Pol signals.

Pic 4 - Ah, rota-click. A good Antiference design that worked well. Incidently, the Band III elements had a letter code stamped on the flattened-out ends. The letter code indicated the element's length. Only the folded-dipole in these, their later, Band III designs did not have this code. If you try dismantling one that has been up on the roof for 40 years you most likely will discover the spring has corroded away - but the rest is usually quite salvageable.
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Old 21st Dec 2015, 9:24 pm   #307
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Default Re: 405-Line VHF Aerials 2013 to the present day.

ORTF & Co. – thanks very much for all of the information about the (diverse) French VHF TV scene that you packed into your post #304.

Something that has occurred to me is that the aerials for channels F2 and F4 must have been of relatively wide bandwidth (in order to cover the 14 MHz French channels) as compared with the single-channel Band I aerials used elsewhere.

At least according to the list in Wireless World 1959 March (page attached), there was also a channel F3, vision at 56.15 MHz and sound at 67.30 MHz. It appears not to have been used, though. And I suspect that it may have been very difficult to use. Being a “bêche” channel, it would have required low side receiver oscillator injection (unless double conversion was used). An oscillator frequency of 28.1 MHz would have been needed to obtain the standard vision IF of 28.05 MHz, and I don’t think that would work! I guess though that the tête-bêche channelling plan was established several years before the standard IF, so that the conflict would not have been anticipated at the time F3 was allocated.

The tête-bêche channelling plan appears to have been developed ahead of the ITU 1952 Stockholm European VHF allocations meeting. It was mentioned, along with the “outband” 162 to 174 MHz allocation, in the WW report on that meeting, in the 1952 October issue, pertinent pages attached. The tête-bêche plan apparently superseded an earlier Band III-only plan that was mentioned by Kerkhof & Werner. One supposes that channel F8A was the original 174-to-188 MHz channel, retained in the new series because it was already in use at Paris and Lille. On the other hand, there was no mention of an existing or planned French standard TV intermediate frequency in the WW 1954 July summary of the EBU TV IF enquiry, so I assume that the 28.05 MHz vision IF number (39.2 MHz sound) was developed later than that.

Looking at the map showing the foreign TV reception areas of France back in the VHF days, one has the impression that there were four kinds of overlap areas, namely: systems E and A; systems E and B; systems E, C and F; and systems E and F. That might have indicated four kinds of dual-multi-standard receiver, but then once a receiver has been designed for E and B, it would not have been a major step to extend its capability to also cover C and F. So it should not be surprising if multistandard receivers for the north-eastern and eastern overlap regions coalesced on four-system, B, C, E and F designs. Then system A was the outlier, to be addressed either by E/A dual–standard or E/A/B/C/F five-standard receivers.

The four system, E/B/C/F receivers on the face of it might have been quite similar to the customary Belgian four-system receivers. But I wonder if there might have been differences nonetheless. From the schematics that I have seen, the Belgian receivers, at least in the valve, VHF-only days covered only some of the French VHF channels, typically F8A plus one or two others in Band III. Also, it is not clear that much or any effort was made to obtain extended vision IF bandwidth on system E. Rather it looks more as if system E had the same vision IF bandwidth that was used for systems B, C and F.

Against that, one might have expected the French setmakers to have given pride of place to system E in their multistandard receivers, with coverage of all of the F-series VHF channels, Band I and Band III, and reasonably good vision bandwidth. Judging by the comments in WW 1959 October, attached, vision bandwidth was a sales feature for French TV receivers, with 9 MHz usual and 10 MHz not uncommon.

That the 1960 January map uses the EBU/CCIR systems letters is interesting. So far I have not found any information as to when the VHF systems letters A through F were actually established. But their use in a 1960 January publication at least indicates that their establishment date was no later than 1959 (The UHF system letters G through K were established either at or in connection with the 1961 Stockholm VHF-UHF planning meeting.)

Getting back to VHF TV aerials, I have attached a picture of a typical local installation. Although the photo was taken back in 2013, that aerial is still in place. The Band I aerial is wideband, covering channels NZ1 through NZ3, 44 to 68 MHz. Channel NZ1 was 44 to 51 MHz, and channels NZ2 and NZ3 covered 54 to 68 MHz. That odd spacing came about because the ITU Region 3 Band I allocation (from Atlantic City 1947) was split, 44 to 50 and 54 to 68 MHz. NZ also had dispensation to use 50 to 51 MHZ for TV broadcasting, recorded I think at the Geneva 1959 meeting. We had regional transmitters on channels NZ1 and NZ3.

That aerial is typical of what one sees in these parts. From our back yard, in a 180 degree arc, I can see around 10 similar installations nearby, some with 3-element and some with 2-element Band I arrays. I haven’t counted the number I can see from the front yard, but it would be similar.

Cheers,
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Old 22nd Dec 2015, 4:20 pm   #308
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Synchrodyne, re: the pic in post no. 307,

"A fine sight !" (and nice and shiny too...)
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Old 22nd Dec 2015, 6:43 pm   #309
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Is it just me or are the pages posted by syncrodyne unreadable?
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Old 22nd Dec 2015, 6:57 pm   #310
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Default Re: 405-Line VHF Aerials 2013 to the present day.

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Is it just me or are the pages posted by syncrodyne unreadable?
I assume you mean the attachments. If so, then yes, I'm afraid the text is barely legibly because of the way the files have been compressed.
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Old 22nd Dec 2015, 8:29 pm   #311
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Apologies for that. I'll redo those attachments and attempt to get better resolution. However, it seems that even if one starts with a carefully reduced .gif or .png, the forum software compresses it further and converts it to .jpg, not good for text. Maybe .pdf would be better here?

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Old 22nd Dec 2015, 9:42 pm   #312
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Yes, try a PDF
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Old 22nd Dec 2015, 10:11 pm   #313
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Default Re: 405-Line VHF Aerials 2013 to the present day.

OK, here is a. pdf set of the four text attachments to post #307. Please let me know their readability. Thanks!

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Old 22nd Dec 2015, 10:17 pm   #314
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Default Re: 405-Line VHF Aerials 2013 to the present day.

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Synchrodyne, re: the pic in post no. 307,

"A fine sight !" (and nice and shiny too...)
Yes. As best I can determine, that installation dates from circa 1998, so it is quite young as Band I aerials go. The blue sky background is normal for these parts and a whole bunch of orders of magnitude older.

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Old 23rd Dec 2015, 12:11 pm   #315
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Synchrodyne, thanks for the 4 .pdfs. They are perfectly legible.

I was wondering whether the later 625 line L3 allocation was rooted in the mists of time with the 819 F3 allocation?
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Old 23rd Dec 2015, 1:26 pm   #316
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Default Re: 405-Line VHF Aerials 2013 to the present day.

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Synchrodyne, thanks for the 4 .pdfs. They are perfectly legible.
Yes, absolutely perfect now, thanks!
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Old 23rd Dec 2015, 9:20 pm   #317
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I was wondering whether the later 625 line L3 allocation was rooted in the mists of time with the 819 F3 allocation?
That I don’t know. It certainly seems to be an odd allocation, though. Perhaps ORTF & Co can help here.

More generally, my understanding is that System L was originally developed for use at UHF, and in the standard European 8 MHz UHF channel. The positive vision/AM sound format was chosen to simplify the design of E/L dual-standard receivers. On the other hand, for its Outré-Mer territories, where dual-standards were not an issue, the French chose system K’, which was negative/FM.

Systems L and K’ “shoe-horned” both a 6.0 MHz main vision sideband and a 1.25 MHz vestigial sideband into the 8 MHz channel, when by conventional reckoning, that combination would have required an 8.5 MHz channel. Recall that in the UK, the TAC had determined that the optimum use of an 8 MHz channel, as compared with the Gerber 7 MHz channel, was to add 0.5 MHz to each sideband, to obtain a 5.5 plus 1.25 MHz sideband combination. The extant Russian system D with 8 MHz channels used the 6.0 plus 0.75 MHz combination. I understand that the 6.0 MHz number was chosen to give horizontal definition commensurate with that of 16 mm movie film. The 0.75 MHz number was probably copied from NTSC practice, which was the foundation for the early Russian 625-line work. That there was “shoe-horning” with Systems L and K’ wasn’t so surprising. System E had been designed for a 14 MHz channel, but the spacing was reduced to 13.15 MHz with the tête-bêche channelling plan.

Apparently also for dual-standard receiver simplicity, the system L standard IF was set (by SCART, I think) at 37.2 MHz vision, 39.2 MHz sound, thus providing sound carrier commonality with System E (28.05 MHz vision, 39.2 MHz sound). This required oscillator-low for the standard UHF channels, as compared with oscillator high for the other European UHF systems G through K.

Then in the 1980s, system L was backfitted to VHF Bands I and III. For Band III that wasn’t a problem, as oscillator-low was quite feasible. But as with channel F3, oscillator-low was not workable for Band I, so the solution was to use reversed channels, with the vision carrier at the high end and the sound carrier at the low end, thus requiring oscillator-high. This re-arrangement was designated as System L’. So one might say that the System L’ channels owed something to the channel F3 case history.

In detail, though, the “L” series VHF channels were somewhat unusual. The Band III channels, L5 through L10, were upshifted by 0.75 MHz from where one might expect them to have been, so they occupied a band running from 174.75 through 222.75 MHz. That has no immediately apparent rationale.

In Band I, L1 (never used, I think), L2 and L4 ran consecutively over the band 41 to 65 MHz. Even this was unusual, given that customary Band I practice was to push the channels to the upper end of the band, leaving a gap, if any existed, at the bottom. Then L3 was an overlap channel, running 53.75 to 61.75 MHz. At least it had the same 0.75 MHz upwards offset as the Band III channels. Here is a very wild guess about L3, if nothing else appropriate for this thread. I think that it would have been receivable on existing channel F4 aerials, which roughly covered the band 54 to 68 MHz. So perhaps it was used in areas that previously had a channel F4 system E service, but where the use of channel L4 (also receivable on an F4 aerial) was inappropriate for one reason or another. That way, viewers could avail themselves of the new system L’ service without requiring a new aerial installation.

System L’ might have caused a few headaches for the makers of multistandard receivers. One solution was the double-Nyquist SAWF. This was a compromise, though, with restricted vision bandwidth both ways, but probably more so for system L’, which also had a very steep Nyquist slope. Although maybe the last-mentioned didn’t matter much; the wider vestigial sideband and consequent more gradual Nyquist slope was advantageous in reducing phase distortion with conventional L-C tuned circuits, but as far as I know SAWFs could be designed to have any desired group delay characteristics almost independently of the frequency response characteristics.

Anyway, the interesting and topic-centred question that comes out of this is were the French VHF L/L’ channel allocations planned so that to some extent at least, viewers could re-use their existing VHF system E aerials?

Cheers,
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Old 24th Dec 2015, 1:03 pm   #318
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Has anybody spotted one of these yet? It's a combined Band III vertical/Band V horizontal aerial for Winter Hill. Have to admit I visited Bolton often in the 1960s and never once noticed that BBC and ITV were both on Band III.
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Old 24th Dec 2015, 4:37 pm   #319
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Default Re: 405-Line VHF Aerials 2013 to the present day.

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Has anybody spotted one of these yet? It's a combined Band III vertical/Band V horizontal aerial for Winter Hill. Have to admit I visited Bolton often in the 1960s and never once noticed that BBC and ITV were both on Band III.
we fitted a lot of these, both the 3 element band three and I think they made a 5 element Band 3 with more elements for UHF, Channels 9, 12, 55, 59, 62, although we always found BBC1 to be much weaker than ITV that caused cross mod in RF stage. Always required an attenuator to stop it but it never caused the BBC1 too be noisy.
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Old 24th Dec 2015, 4:43 pm   #320
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Spotted these in Haverhill today, pointing south, presume Crystal Palace?
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