2. WIRING
2-11
2.3.2 Installing the Rectangular Waveguide WRI-84 (WRJ-9)
The RF interconnection between the antenna unit and the transceiver can be made
with a rectangular waveguide WRI-84 (WRJ-9) or flexible (FR-9). If the rectangular
waveguide is used, observe the following installation guidelines.
• Correctly installed waveguide runs ensure the most efficient transmission of electri-
cal energy at high frequencies. Electrical losses, however, occur in the waveguide
runs. To minimize them the following factors are of great importance: minimum
length, airtightness and electrical continuity.
• Another consideration required is that of frequency disturbance. The transmitting
valve, a magnetron, is the primary oscillator in the radar. This is different from the
oscillation system at lower frequencies in which conventional radio valves are used.
In the latter case, the primary oscillator is always protected from the effects of load
impedance by a buffer stage so that frequency and waveform are left unobstructed.
With a waveguide and magnetron, however, mismatch of impedance causes "fre-
quency pulling." For this reason, the number of possible mismatches in a waveguide
run, i.e., joins and bends, must be kept minimum.
• Each pair of flanges should be coupled with one O-ring, four bolts and spring wash-
ers and the choke flange must be in the upper position. The bolts and O-ring must
be greased before insertion to facilitate removal if required at a later date.
• The transceiver unit output flange is a plain type and the antenna unit output flange
is a choke type, and it is important to maintain this relationship throughout the wave-
guide run.
• After installation of the waveguide is completed, the coupling portions must be
sealed by using the adhesive supplied.
• In a very short time the surface of the waveguide becomes green with verdigris.
Therefore, paint both the surface of the waveguide and flanges to avoid corrosion
and water penetration. Paint must not be allowed to reach the inner surface of the
waveguide or the mating surface of any flange.
Thru-deck hole
Weld here.
Deck
TRANSCEIVER
UNIT
Drain waveguide
Watertight film
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