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)

Installing a Model 6832 FM Antenna

Installation of the Shively Labs Model 6832 antenna is quite simple. All you will need is your installation drawing and this instruction sheet. If you have any problems, call Shively and talk with the designer.

Check Shipment

Before beginning, be sure to check your shipment to be sure all the parts are there. The parts are listed on the installation drawing.

Installation

	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. RF emissions at close range are hazardous.

1. Mark the tower at the locations where the antenna bays will be mounted. The bay spacing is critical. Watch for tower components that might interfere with your installation.
2. Assemble the antenna bays.

   	The installation drawing for your antenna shows the assembly in detail.

   • Using 1/4" x 1-1/2" hardware, attach the two thinner antenna arms to the thinner mounting stubs.
   • Next, attach the two thicker arms to the thicker stubs.
   • Remove the bolt and washer from the center of the end seal (the white plastic dome). Using this bolt and washer, attach the feed strap to the end seal. Attach the ends of the feed strap to the bolt holes in the thicker arms.

   	Tighten the end seal bolt only until the lock washer flattens. Do not overtighten.

   • Tighten all the hardware before continuing.
3. Attach the bay mounts to the antenna bays. Any mount can be used with any bay. The center of the end seal should be located 3/8" from the outer edge of the mount on each bay.

	Do not attach the bays together with the RF cable before mounting them. NEVER try to support the bays from the cable.
	Before attaching the mounts to the tower, scrape away tower paint to ensure good electrical contact. If you don’t, the antenna will generate unwanted electrical signals.

4. Mount the antenna bays to the tower at the locations you marked.

	We ship two sizes of U-bolts with each antenna, to cover a wider range of tower leg diameters. Use the U-bolts that best fit your tower legs. Double-check the mounts at this time to be sure they are secure.

	Don't overtighten the DIN connectors. Overtightening them may damage them.

5. Attach the feedline cable to the antenna bay terminals as shown in the installation drawing. Be sure all the connections are tight.
6. Attach the input end of the cable to the tower transmission cable. Be sure the connection is tight.

Your Model 6832 installation is now complete. We hope you find the unit satisfactory in every way.

Startup

When all personnel are clear of the tower, apply a low-power signal to the antenna and read the VSWR. The VSWR should be below 1.5: 1. If it is not, call Shively and speak with the designer.

	The Model 6832 does not require pressurization or purging.

Operation

Once the antenna has been installed and VSWR has been confirmed, simply apply the transmitter signal. Don’t exceed the rated power of the antenna.

Troubleshooting

Broad Spectrum RF Noise:

This indicates that some component is not in good electrical contact with the tower. Make sure mounts are tight, that tower paint has been removed from under the mounts, and that components of other systems are likewise in good contact with the tower.

High VSWR:

This is caused by any factor that changes the impedance match between the antenna and the transmitter. Look for:

• Defective RF connector. Make sure connectors are in good shape, and that center pins are not bent over.
• Damage to any antenna components, especially the feed strap on each antenna.
• Incorrect assembly. Is a radiator upside-down, or the bay spacing not as shown in the installation drawing?
• Paint on radiators.
• Interference from other tower components, especially components broken by wind or ice.

Change in Coverage:

This may be caused by the same factors that can cause high VSWR. Look for VSWR changes as well.

Do recognize, however, that apparent changes in coverage may be due to subjective factors or faults of the receiving equipment. Before doing more than checking the VSWR, be sure that an actual coverage change has occurred.

Maintenance

	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. RF emissions at close range are hazardous.

Log:

We recommend that you keep a log of VSWR readings and any other performance notes and maintenance history for your antenna. Such a log can be invaluable for troubleshooting.

Inspection:

Whenever a rigger is on the tower for any reason, it is a good idea to have him check your antenna for general condition, looseness of connectors and mounts, and electrical damage.

Paint:

The radiator should never be painted; this will affect the VSWR.

Radiator Removal for Repair:

Depending on your transmitter, it may be possible to remove one radiator to have it repaired. If this is done, power will have to be reduced proportionately and VSWR will rise.

Return Policy:

When returning any material to the factory, be sure to call your salesperson and obtain an authorized return order (ARO) number first. Material may be refused and sent back to you at your expense if you don’t do this.

	Printer-friendly Adobe Acrobat version
	Get Acrobat Reader (free download)