Technical bulletins

References for the RF industry

Technical sheets

"How-tos" on Shively products

• "Shively Labs Meets the Very Windy Mountain"
  from May-June 2008 Radio Guide
• "Shively Labs: Antennas That Work!"
  from September 2007 Radio Guide [279 kB]
• "Shively 6014 Dual Hybrid Antenna Solves a Dilemma"
  from September 2007 Radio Guide [232 kB]
• Vermont Public Radio's Mt. Mansfield Project (October '06)
• West Virginia Public Radio chooses BE, Shively (reprinted from Radio Currents, 6/5/06)
• Interdigital combining technology at 4 Times Square (July '05)
• 4 Times Square, NY: 21-station master FM project (April '04)
• Revolutionary IBOC test at Cougar Mountain (August '02)

Replacing a Feedline Pressure Relief Valve, Shively P/N 52471

Every Shively Labs pressurized feedline is fitted with one or two pressure relief valves. These prevent overpressurization of the line and allow you to purge the line without manual bleeding at the tower end. An end-fed antenna will have a pressure relief valve at the top of the feedline; a center-fed antenna will have two, one at each end of the antenna.

We recommend that you never operate your antenna without a working pressrue relief valve in place. Here is how you may replace a defective pressure relief valve.

	Whenever a rigger is on the tower in the area of the antenna, shut off the signal and lock it off so that it cannot be turned on accidentally.

1. Turn off the signal. The broadcast industry has recently recognized the potential medical hazards of intense radio frequency radiation. Don't expose personnel to personal harm. For reference, see CFR 29, Section 1910.97, the OSHA standard for exposure to non-ionizing radiation.
2. Do not turn off the dry air or dry nitrogen flow and pressure to the feedline. If you perform the replacement quickly with full dry gas flow, you should not have to re-purge your system before resuming operation.
3. Prepare the new valve for installation by applying a small amount of pipe sealant or PTFE tape to the threads (if there is none there already). Leave the first thread clean to prevent contamination of the feedline interior.
4. Unscrew the defective valve and remove it. Immediately, install the new valve. Tighten it hand-tight, then give it an extra half-turn with a wrench. Do not overtighten the valve; this can distort the valve body and prevent proper seating of the poppet.

	It is all right to test the new valve once or twice to be sure it's working properly, but that's all. Repeated use can wear out the valve prematurely.
	Don't try to readjust the valve. It is factory-adjusted at 10 psig and should be left there.

5. After all personnel are away from the antenna, reapply power to the antenna and resume operation.

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