Smiths Kelvin Hughes Nucleus 3 5000 Series, Системный справочник

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DOWNMAST TRANS CEIVER (CTX-A8)
Con struc tion
28 The gen eral con struc tion of the downmast X-Band
trans ceiver com prises a sheet-metal rear plate which
is formed, to in clude the top of the unit. This is braced by two
‘U’ sec
tions which pro trude above and be low the plate,
pro vid ing the bulk head fix ing points.
29 The PCBs are mounted both sides of the mod u la tor
chas sis and are re moved as a com plete as sem bly.
30
A wrap-around cover made from sheet-metal,
en closes the unit and is fixed by six cap tive screws.
Re moving the cover gives ac cess to the front and sides of
the Trans ceiver elec tron ics. Ca ble en try is at the bot tom of
the unit.
Mount ing
31
Fit the trans ceiver to the se cur ing bulk head us ing the
in stal la tion bolts sup plied with the fit ting kit. Re fer to
Fig ure 4f for di men sions.
WAVE GUIDE IN STAL LA TION
32 This section deals with the installation of the
waveguide between the Turning Mechanism and the
Transmitter/Receiver. It is not concerned with waveguide
items inside the equipment.
33 Carefully and correctly installed waveguides are, up to
the present, the most efficient means of transmitting
electrical energy at high frequencies. Losses inherent in
waveguides are, however, still considerable. To keep them
to a minimum, the following factors are of great importance:
minimum length, air tightness and electrical continuity.
34 The Transmitter, a magnetron type valve, is also the
primary oscillator. Mismatches of impedances in the
waveguide cause reflection of power back to the magnetron
which can result in ‘frequency pulling’ and instability.
Mismatches in a waveguide run can occur at joints, bends
and twists – all of which must be kept to a minimum.
EL LIP TI CAL WAVE GUIDE
35
Detailed instructions for the installation of elliptical
waveguide are given in the following pages.
Original 4f.9 May 01
KH 2020
Chap 4f
WARNING
EN SURE THAT ALL POWER SUP PLIES IN THE
VI CIN ITY OF THE TRANS CEIVER ARE ISO LATED
BE FORE ANY IN STAL LA TION TAKES PLACE.