Federal Signal Corporation YAGI-1, Installation Manual

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8
Installing the Antennas
Yagi and Omni Antennas
Federal Signal www.fedsig.com
Installing the Yagi Antenna
Yagi Antenna Pre-Assembly Instruction
To pre-assemble the antenna:
1. Unpack the antenna and locate the following parts:
• Boom (1-14 inches for 5-element model, 7/8 inch-diameter for 3-element model)
• 3/8 diameter elements (y---3 = 3 elements, y----5 = 5 elements)
• Gamma match parts bag
• Mounting bracket parts bag
2. Find the proper element dimension chart for your antenna within the antenna
instructions, and trim each element according to your operating frequency. Use care
to trim equal lengths from each end of each element to ensure that the mounting
hole is at the center.
NOTE A: Proper trimming and adjustment are critical to the Voltage Standing Wave
Ratio, known as VSWR. (High reflected power levels decrease forward power. The
life of the radio and transmit capabilities are dependent upon the VSWR being low as
possible.)
NOTE B: If two frequencies are being used, then trim the antenna to the transmit
frequency of the system where the antenna is mounted.
3. Insert the elements into their respective locations through the boom, starting with R1
(the reflective element) in the hole closest to the mounting holes. Then insert Dr, D1,
etc., in that order.
NOTE A: The shortest element is furthest away from the mount and increases in size
as it gets closer to the mount.
NOTE B: Be very careful to line up the holes and not cross thread when securing
the elements in the next step. The bolts must tighten all the way down upon the lock
washers.
4. Secure the elements with the stainless steel 10-32 hex bolts and #10 lock washers
provided.
5. Locate the connector/brass tube assembly in the gamma match parts bag, insert
the assembly first through the connector bracket, and thread the connector into the
bracket. Be sure to tighten the connector fully. Use a drop of Locktite® or another
thread lock in the threads to eliminate the possibility of the connector loosening.
6. Slide the gamma link onto the driven element and assemble the gamma match as
shown in Figure 1 or 2. (See the antenna instructions provided by the antenna’s
manufacturer.) Set dimensions “A” and “B” to those shown in table 1. Setting the
match to the dimensions shown for your antenna is a good starting point, which
allows you to quickly line-tune later. Complete the assembly by attaching the end cap
onto the end of the gamma tube. The antenna is now ready for final tuning.