GRA-50\( \).

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MIL-PRF-55371B(CR)

linear dimensions (feet) on one side and corresponding frequency markings (megahertz) on the

other side.

3.4 Construction. The Radio Frequency Measuring Tape shall be constructed in

accordance with the requirements of this specification and shall be capable of passing

verification prior to delivery to the government (see 4. VERIFICATION).

3.5 Performance characteristics.

3.5.1 Graduations and Figures. Tapes shall be graduated for a length of 156 feet.

Graduations and Figures (numbers and letters) shall be permanent and resistant to wear and

abrasion resulting during normal and abnormal use in a wide range of environmental conditions.

Graduation lines shall be uniform and readily distinguishable in their widths. These lines shall

be free from discontinuities and ragged edges. There shall be no noticeable variation in the

widths of like numbers and letters. Each graduation shall be accurately located. Tapes shall be

graduated for reading left-hand to right-hand.

3.5.2 Finish. All exposed metal parts shall be constructed of corrosion-resistant material

or shall be plated with a corrosion resistant plating such as zinc, chromium or nickel. All

exposed metal parts shall be manufactured free of defects, sharp edges, burrs, or any other

physical imperfections which could impair manual handling, or injure the operator (see 3.7).

3.5.3 Case. The case shall house the ribbon and provide for the handling of the tape. The

case shall be consructed of corrosion-resisting metal or a metal with corrosion finish, and shall

be not less than .025 inches thick. Choice of construction is at the option of the contractor, but

the opening in the case intended for the ribbon shall be provided with a durable eyelet having

rollers to act as bearing surfaces on top and bottom sides facing the ribbon. The bearing surface

rollers shall facilitate the deployment of the ribbon when used. The case shall be capable of

withstanding the shock; drop and bounce tests of 4.6.4 et el.

3.5.4 Case Covering. The vnyl cover shall be vnyl coated cloth which is both durable and

water resistant. A stainlesss steel or plated steel furling ring shall be used to cover and securely

hold the edges of the vnyl coated cloth to the case. The vinyl coated shall be mildew resistant.

The vinyl case cover shall be permanently secured to the case with a water adhesive.

3.5.5 Holding strap. A 150 pound tensile strength holding strap, measuring 18 x 1/2 x

1/16 inches, shall be provided across the back of the case. The strap shall be wrapped around

two rollers 5 and 3/8 inches apart. Each roller shall be free to rotate about a pin shaft which

shall be mechanically fastened (e.g. riveted) at both ends to a bracket. Each bracket shall be

mounted to the case via three mechanical fasteners. The strap shall be retained by two sliding

loops. Associated hardware may be of any material which is strong, durable and corrosion

resistant. The strap shall be resistant to ultraviolet deterioration, fungus growth, abrasion, and

moisture, and pliable in temperatures as low as -50 degrees F.

3.5.6 Identification marking. Each tape and ribbon shall be plainly and permanently

marked with the manufacturer's name or with a trademark of such known character that the