MIL-DTL-55288E
c.
Production pack(s) as follows:
Makeup of pack(s)
Number of each kind of pack to be submitted.
Inspection to be performed thereon.
d.
Marking and shipping of samples.
e.
Place of final inspection.
f.
Packaging (see 5.1).
6.3 Color. The color chip furnished by the acquisition agency will be color chip No. 24087, may be obtained upon
request to Commanding Officer, US Naval Supply Depot, 5801 Tabor Avenue, Philadelphia PA 19120.
6.4 Group C inspection. Approval to ship may be withheld at the discretion of the Government, pending the
decision from the contracting officer on the adequacy of corrective action (see 4.5.3.2).
6.5 Location of air-seal test. It is desirable that the air-seal test (see 4.9) be performed at a location that will
minimize handling (which might cause damage to the equipment) after this inspection is completed. Any preparation
for shipment which would require breaking of equipment seal should be accomplished prior to the air-seal test so that
the seal may remain intact thereafter. It is recommended that the entire lot (including all previously inspected sample
units) be sampled and inspected immediately prior to packaging.
6.6 Nomenclature. The contractor should apply for nomenclature in accordance with the applicable clause in the
contract (see 1.1).
6.7 Verification inspection. Verification by the Government will be limited to the amount deemed necessary to
determine compliance with the contract and will be limited in severity to the definitive verification provisions
established in this specification and the contract. The amount of verification inspection by the Government will be
adjusted to make maximum utilization of the contractor's quality system and the quality history of the product.
6.8 Theory of operation. Antenna AS-1729/VRC is electrically equivalent to a vertical dipole of constant length
whose current distribution throughout the operating band is optimized by a pre-selected termination within the base
assembly unit. The upper element of the dipole is a straight-forward conductor. The lower element of the dipole is
the outside surface of a coaxial cable which is terminated, at the bottom end, against ground in a controlled
admittance. The location near the center of the whip, where the upper element joins the inner conductor of the
coaxial cable, is referred to as the feed-point. The coaxial cable making up the lower element has two additional
functions. It serves to supply rf energy to the feed-point and also serves as a coaxial transformer section grouping
the input impedance with a 3:1 VSWR. The termination within the base assembly unit is a ferrite core rf choke whose
susceptance to ground is changed (in ten sub-bands) by alternately shunting nine of the sub-bands with present
variable components. Sub-band number two is controlled by the base choke alone and is not adjustable. The
shunting is accomplished by a step-action rotary solenoid driven switch, which is controlled by a master wafer built
into Radio Set AN-VRC-12. A manual override knob serves to indicate the sub-band in operation and provides a
capability for manual selection of the desired sub-band when the antenna is used with a radio set other than those
listed in 6.1.
6.9 Antenna test chamber. The antenna test chamber is used to facilitate indoor electrical testing of Antenna
Matching Unit-Base MX-6707/VRC during production. The chamber is a twelve inch diameter tube, six feet long, the
interior contains either ferrite tile or ferrite rings. A modified lower whip section is mounted axially within the chamber.
A nine inch copper disk with a short stub at the center that has been tailored to electrically represent the top whip
section, screws into the top end of the modified lower whip section. The chamber provides a unique correlation
between the impedance of an antenna within the chamber and the same antenna over a reference ten feet by ten
feet ground screen in free space. Because the antenna impedance in the chamber at some frequency in each sub-
band is within the VSWR requirements of this specification, meaningful rf power tests on the MX-6707/VRC can be
accomplished in the chamber.
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