User Manual

2-2 Installing the PTX-PRO PTX-PRO User and Technical Manual
WARNING - RF Power Hazard
WARNING
The unit has high levels of RF power. Exposure to RF or microwave
power can cause burns and may be harmful to health.
• Remove power from the unit before disconnecting any RF cables and before inspecting
damaged cables and/or antennas.
• Avoid standing in front of high gain antennas (such as a dish antenna) and never look
into the open end of a waveguide or cable where RF power may be present.
The following guidelines for safe operation were derived from OET bulletin 65, August 1997, as
recommended by the Federal Communications Commission (FCC).
The PTX-PRO was designed to provide services to broadcast ENG users under CFR 74
subpart F and 74.601 TV pickup stations. This unit, operated without an antenna, will not create
RF energy exceeding 1.0 mW/cm
2
, the FCC limit for exposure. Once connected to an antenna,
the potential for harmful exposure will be greatly enhanced.
In this situation, a certain distance from the radiator is to be maintained. Calculations need to be
performed to understand what that safe margin for exposure is. This is known as the Maximum
Permissible Exposure (MPE) limit.
Calculations provided are for common antennas often utilized in the ENG environment. The
following formula used is that suggested by OET 65.
Calculating MPE
EIRP = P * (10 ^ (G / 10)) = (antilog of G/10) * P
P = RF power delivered to the antenna in mW
G = Power gain of the antenna in the direction of interest relative to an isotropic radiator
R = distance to the center of radiation of the antenna in centimeters
S = MPE in mW/cm² (milliwatts per square centimeters)
Conversions
dBi to numeric gain = Antilog (dBi/10)
Feet to centimeters = Feet * 30.48
Centimeters to Feet = cm * .0328
4 π = 12.57
User Input
RF power delivered to the antenna = Watts
Antenna gain (referenced to isotropic antenna) = dBi
Distance from the center of radiation = Feet