CAL-AV Labs, Inc.

Quality Engineering Solutions Since 1959

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Information Sheet

Mark-7 Mobile Antenna Spring

Thank you for purchasing the Mark-7 spring. This spring is intended for exceptionally large whips, masts, and remotely-tuned HF antennas. We hope you will enjoy many years of good mobile operation with it. The Mark-7 is constructed of stainless steel, except for the tinned copper braid, which is internally connected from one end to the other.

Size: Approximately 3.7” diameter, approximately 8.45” long
Weight: 10.5 pounds.
Bending torque: Approximately 95 foot-pounds for a 10 degree deflection. Torque is measured with a perpendicular load applied 36 inches above the spring base.

Install the spring using a 5/8-18 stud or bolt. If purchasing hardware from a hardware store, ask for a GRADE-8, or stainless bolt. If using stainless hardware, be absolutely sure to use anti-seize compound to avoid galling. A 5/8" stainless split-ring lock washer may be used on either or both ends as desired. In one flat on each end of the spring is a tapped hole. In each of these holes is a lubricated stainless ¼-28 set screw. After tightening the spring to base and antenna mast to spring, tighten the set screws using the hex wrench provided. This will reduce the chances of the spring or mast loosening during usage.
Use the flats machined into the spring ends for tightening, and for preventing the ends from turning in the spring while tightening a whip or loading coil.
Occasionally, drop a few drops of LPS-3 into the top threaded hole. The LPS-3 will wick down into the tinned braid to protect it from the elements. This is more important in wet climates.

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Voice: 520.624.1300 | Email:

1985 North El Moraga Drive
Tucson, AZ 85745-9070

Mobile Antenna / Mast Spring Assemblies
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