User Guide: Technical Reference
SECTION 2
ioLink 4
SYSTEM COMPONENTS
PRELIMINARY
Customer Support (202) 333-7031
2-5
The RF board contains oscillators and amplifiers, including the Power Amplifier (PA), Voltage Controlled
Oscillator (VCO), the Low Noise Amplifier (LNA), ceramic filters, a mixer, and synthesizer chip. The RF
board also contains the connections to the modem unit as well as to the antenna (see the following RF
unit block diagram).
The RF unit has a NEMA-4 enclosure to protect the unit from harsh environmental conditions. The
enclosure is sealed to be weatherproof and can operate at temperatures between –40
o
C and +60
o
C
without damage to the internal circuitry. A vent device on the enclosure allows pressure equalization
without compromising the environmental seal. The RF unit must be mounted so that vent immersion is
not possible. To help protect against lightning strikes, the unit should be grounded to a support structure
via the unit’s grounding stud. The RF unit may be stored in a temperature range of –40
o
C to +60
o
C.
2.4 Radio Frequency Cable
The RF unit is connected to the antenna by a single, low-loss 50 ohm coaxial cable called an RF cable.
The antenna and the RF unit should be placed as close as possible. The RF cable should also be tied
down to the support structure to minimize movement and stress from high wind. In lightning susceptible
installations, a lightning arrestor such as a Poly Phaser™ Mode IS-MF 50LN is recommended.
Figure 2-4. RF Unit Block Diagram
Synthesized
Local
Oscillator
Diplexor
or
Cavity
Filters
Ceramic
Mixer
Mixer
Antenna
Ceramic
PA
LNA
From Modem
Unit
To Modem Unit
at 70 MHz
