photos d'antennes droles,hors normes...

marceljack a écrit ↗kiki37 pourrait peut-être nous en dire un peu plus sur l'origine de cette photo ... et sur ce que cette installation était censée faire.
Vu la couleur de certains coax (gaines marron) la photo pourrait venir d'Outre-Manche car c'est le seul endoit où j'ai vu des coax de cette couleur.

Citation :The

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heart of a distribution system providing TV reception for about

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40 bungalows, this is a typical head-end from the early 1970s.

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The unit was custom built on a steel plate, using amplifiers,

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combiner and splitters. Connections were unscreened. Power was

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12VDC from the PSU at bottom right. These boards were generally

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adequate for VHF TV, but struggled to provide adequate signals

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levels for UHF, because of the much greater cable and tap-off

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losses. These boards were very reliable, and I’ve often removed 30 year-old examples in full working order.

Citation :These aerials were found at the head-end of a distribution system. Amazingly the system was still providing UHF reception, having worked untouched for over twenty years! The original installer evidently discovered than an eight element Band III aerial and a Band I ‘X’ aerial won’t fit easily in a loft. These are actually outdoor aerials. Because of the large size of VHF aerials most manufacturers had special loft versions that had flexible or telescopic elements. The Band III aerial is fixed half way up the mast, but the ‘X’ can’t have ever been fitted at the top – there just isn’t room. The mast is a swan-neck type, normally used the other way up. The installer has marked the active elements with red tape. It was generally assumed that the side of the dipole connected to the coaxial inner should be at the top.

Coplan a écrit ↗Pour les "ceusses" qui ont pratiqué les installations d'antenne je suis sur qu'ils ont du en voir des vertes et des pas mûres dans leur carrière.

Citation :Jay

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Beam, or J-Beam as it later became, sold a range of high gain

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UHF aerials, the ‘Multibeam’ range, based on a square

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dipole, with matching reflector. These were the first TV aerials

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to have quad bay director elements. The original product range

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was the MBM30, MBM46 (pictured), and MBM70. The MBM46 later became

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the MBM48, and the MBM70 was replaced by the MBM88. The gain of

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all these aerials was excellent, with the MBM46/48 probably providing

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the best practical compromise between size and performance. The

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aerials had baluns built into the connector box. The build quality

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was excellent with solid elements and diecast dipole, but deteriorated

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in later years. The Achilles’ heel was the front/back ratio,

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which was poor. These aerial were no good if there were reflections

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from the rear. For pure gain, however, they were the tops. Antiference had nothing comparable.

Citation :After

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Antiference swallowed up Belling Lee’s aerial division in

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1968 we had the ‘big four’ – Antiference, J Beam,

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Wolsey, and Aerialite. In the early UHF days Aerialite produced

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a range of very well made yagis, but soon they needed a product

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to compete with the J Beam high gain range. The result was the

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‘Supreme’, and other smaller arrays with equally silly

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names. The photograph shows an early example. Later versions had

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an ‘S’ shaped reflector similar to the directors. This

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allowed the aerials to be supplied in a small box with all elements

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folded flat, a great sales point because J Beam boxes were huge,

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and riggers’ vans were generally smaller than they are nowadays!

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The ‘Supreme’ worked quite well, with gain roughly the

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same as the Jaybeam MBM46, but with much better directional properties.

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MBMs were a poor choice if there was a problem with ghosting,

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but Supremes were quite good in that respect. A strange weakness

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of the Supreme was that the cradle would fill with water. After

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a hard frost the aluminium would burst open, but I never knew

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of one actually failing because of this. Aerialite was taken over by Antiference in 1981.

cricri a écrit ↗Bonjour
Pour info j ai demandé ce jour à clôturer mon compte et supprimer mes participations à ce forum
L ambiance n y est pas bonne, dès que on dit un truc on se fait dézinguer
Trop c est trop
Je tire ma révérence définitivement
@+

cricri a écrit ↗Bonjour
Pour info j ai demandé ce jour à clôturer mon compte et supprimer mes participations à ce forum
L ambiance n y est pas bonne, dès que on dit un truc on se fait dézinguer
Trop c est trop
Je tire ma révérence définitivement
@+

cricri a écrit ↗Bonjour
Pour info j ai demandé ce jour à clôturer mon compte et supprimer mes participations à ce forum
L ambiance n y est pas bonne, dès que on dit un truc on se fait dézinguer
Trop c est trop
Je tire ma révérence définitivement
@+

Citation :

Citation :cricri surpris en plein travai

cricri a écrit ↗
Photos et un article complet ici:
https://www.w5rrr.org/2019/01/09/satellite-antenna-maintenance/
Good job guys!

kiki37 a écrit ↗cricri surpris en plein travai ▼

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