Telephonics RDR-1600, Installation Manual

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O M M A N D
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Y S T E M S
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I V I S I O N
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Before ordering nonstandard large radius waveguide bends, see if the same result can be obtained
by using standard bends with additional length in the straight sections.
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When specifying unavoidable special bends in rigid waveguide, use an exact radius of 2.214
inches to the waveguide centerline for all shaft bends in either E or H plane and seven inches
centerline radius or greater in large bends.
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Each individual section of rigid waveguide should contain no more than one bend. This
procedure simplifies maintenance of the transmission line.
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Remember to allow sufficient clearance to permit access to flange connecting screws.
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Use waveguide quick disconnects wherever joints are to be broken repeatedly for maintenance,
inspection, or access to other equipment, or to assure good joint sealing in relatively inaccessible
locations.
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Be certain that the mating of a choke flange and a cover flange makes each joint in the waveguide
run. This type joint will permit proper RF sealing of the line. Each waveguide section should
have a choke flange and a cover flange at its opposite ends, where possible. Carefully avoid
specifying nonstandard flanges, such as choke flanges with tapped screw holes.
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Axial twists in rigid waveguide, up to 90 degrees, should be considered as being made in
approximately an eight-inch length of waveguide. Before specifying twists in rigid waveguide,
make certain that the same result cannot be more easily accomplished by properly oriented bends
in a section of flexible waveguide.
The following points should be observed in the use of flexible waveguide components:
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Use standard flexible components wherever possible. Minimize the number of joints in the
waveguide run.
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Locate a flexible section at the points of attachment to the antenna unit and the RT unit. These
sections will provide expansion joints in positions where the installation or removal or rigid
waveguide would be exceedingly difficult.
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Flexible waveguide should be used instead of rigid sections containing complex bends wherever
possible. Compound bends and apparent twists can be obtained through the use of flexible
waveguide, usually at lower cost and with some simplification of installation.
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In any single installation, attempt to use the same length of flexible waveguide for all flexible
sections of the transmission line.
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Clamp flexible waveguide firmly to a solid portion of the aircraft structure at least once in each
18 inches of waveguide run.
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Design flexible waveguide clamps carefully so that they do not distort the waveguide walls.
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Use waveguide quick disconnects wherever joints are to be broken repeatedly or to assure good
joint sealing in relatively inaccessible locations.
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Use flexible waveguide to produce the same effect as a twist in rigid waveguide components.
Any combination of two alternate (right and left) 90-degree bends in either the E or H plane
(broad or narrow wall) with any 90-degree bend in the opposite plane between them will
produce an effective waveguide twist. Such flexible components are less expensive and more
easily installed than rigid twists.