CHPA SERIES
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.01023245
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2-5
2.5.7
RF Output (Waveguide Connection)(J3)
The output waveguide flange of the CHPA is located on the rear panel of the CHPA. The
standard RF output interface, provided by the user, to connect the CHPA to the external
waveguide run is a flange termination. Use the following waveguide flange depending on the
CHPA band:
•
CPR-137 for C-band
•
WR-75 for Ku-band
•
WR-62 for high Ku-band (typically used for DBS applications).
The CHPA comes equipped with a grooved, threaded rear connector. An O-ring gasket is
supplied in the ship kit.
To install the waveguide flange, proceed as follows:
1.
Install the O-ring gasket (supplied) in the output flange of the CHPA.
2.
Position the interconnecting waveguide so that it aligns precisely with the waveguide flange
at the rear of the CHPA.
3.
If alignment is not precise, or if the installation is subject to motion or severe vibration, a
flexible waveguide section should be installed between the output of the CHPA and the
interconnecting waveguide.
4.
After alignment is verified in all three planes, loosely attach the interconnecting waveguide
to the output waveguide flange of the CHPA. Start all bolts and verify proper alignment
before uniformly tightening the bolts.
5.
Carefully tighten all bolts (in opposite pairs rather than sequentially around the perimeter of
the flange) so that the connection is firm. Do not over tighten because this can strip the
threads or distort the mating flange. Recommended torque is 30 in-lbs for #10-32 (C-band)
and 10 in-lbs for #6-32 (Ku-band).
2.5.8 Cooling
Considerations
The CHPA is forced-air cooled. The exhaust air from the CHPA may be at a relatively high
temperature (approximately 35°C above ambient temperature), and heat dissipation may be as
high as 2000 watts. To prevent excessive heat buildup in the rack cabinet, it is recommended
that the exhaust air be ducted away from the CHPA; an air duct is provided for this purpose.
The external ducting must have a cross-sectional area at least equal to that of the exhaust
opening. Minimum airflow required for proper cooling of the CHPA is 120 CFM at sea level
(540 LB/HR). To meet this airflow requirement, external back pressure or intake drag must be
limited to 0.10 inch of water column (0.25 cm). Exhaust duct bends and transitions must be
smooth and bend radii should be as large as possible to promote proper cooling.