Exposure to radio frequency (RF) energy has been identified as a potential environmental factor that must be considered before a radio transmitter
can be authorized or licensed. The FCC and IC have therefore developed maximum permissible exposure (MPE) limits for field strength and power
density, listed in FCC 47 CFR § 1.1310 and IC RSS-102 Issue 2 Sect 4. The FCC has furthermore determined that determination of compliance with
these exposure limits, and preparation of an Environmental Assessment (EA) if the limits are exceeded, is necessary only for facilities, operations
and transmitters that fall into certain risk categories, listed in FCC 47 CFR § 1.1307 (b), Table 1. All other facilities, operations and transmitters are
categorically excluded from making such studies or preparing an EA, except as indicated in FCC 47 CFR §§ 1.1307 (c) and (d).
Revised FCC OET Bulletin 65 (Edition 97-01) and IC RSS-102 Issue 2 provide assistance in determining whether a proposed or existing transmitting
facility, operation or device complies with RF exposure limits. In accordance with OET Bulletin 65, FCC 47 CFR § 1.1307 (b) and RSS-102 Issue
Sect 2.5, the Codan Radio Communications transmitter manufactured in Canada is categorically excluded from routine evaluation or preparing an
EA for RF emissions and this exclusion is sufficient basis for assuming compliance with FCC/IC MPE limits. This exclusion is subject to the limits
specified in FCC 47 CFR §§ 1.1307 (b), 1.1310 and IC RSS-102 Issue 2 Sect 4. Codan Radio Communications has no reason to believe that the
excluded transmitter encompasses exceptional characteristics that could cause non-compliance.
Notes:
•The FCC and IC’s exposure guidelines constitute exposure limits, not emission limits. They are relevant to locations that • are accessible to
workers or members of the public. Such access can be restricted or controlled by appropriate means (i.e., fences, warning signs and others).
•The FCC and IC’s limits apply cumulatively to all sources of RF emissions affecting a given site. Sites exceeding these • limits are subject to an
EA and must provide test reports indicating compliance.
RF Safety Guidelines and Information
Base and Repeater radio transmitters are designed to generate and radiate RF energy by means of an external antenna, typically mounted at a
significant height above ground to provide adequate signal coverage. To reduce potential radio interference to other users, the antenna type and its
gain should be so chosen that the equivalent isotropically radiated power (EIRP) is not more than that permitted for successful communication. The
following antenna installation guidelines are extracted from Appendix A from OET Bulletin 65 and must be adhered to in order to ensure RF
exposure compliance:
Non-building-mounted Antennas:
Height above ground level to lowest point of antenna ≥ 10 m
•Power ≤ 1000 W ERP (1640 W EIRP)
Building-mounted Antennas:
Power ≤ 1000 W ERP (1640 W EIRP)
The following RF Safety Guidelines should be observed when working in or around transmitter sites:
The minimum safe distance the user should be from the transmitter antenna while transmitting is 142 cm for transmitters 8W or
less and 300 cm for amplifiers 30W or less. This assumes a maximum antenna EIRP of 15 dBi.
• Do not work on or around any transmitting antenna while RF power is applied.
• Before working on an antenna, disable the appropriate transmitter and ensure a “DO NOT USE” or similar sign is placed on or
near the PTT or key-up control.
• Assume all antennas are active unless specifically indicated otherwise.
• Never operate a transmitter with the cover removed.
• Ensure all personnel entering a transmitter site have electromagnetic energy awareness training.
For more information on RF energy exposure and compliance, please refer to the following:
FCC Code of Regulations; 47 CFR §§ 1.1307 and 1.1310
•FCC OET Bulletin 65, Edition 97-01, “Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency
Electromagnetic Fields”
• http://www.fcc.gov/oet/rfsafety/
• IC RSS-102 Issue 2, “Radio Frequency Exposure Compliance of Radio Communication Apparatus”
Power Amplifier AMP-4-410-30-00
User Manual
1. General Description
The power amplifier (PA) is a one stage unit, working in AB-class operation mode. In addition to the power
amplifier section, the PA contains the power control, status monitoring and protecting circuitry, as well as
voltage regulation for supplying the RF and main control circuits.
The output power may be controlled either by the external analog signal (remote control), or by potentiometer,
accessible from the front panel (local control).
The voltage regulator turns on, when all four of the following conditions are present:
- remote control voltage (in the case of remote control) is greater than 1 V;
- input power is not less than 0.5 W;
- the case temperature does not exceed + 85°C;
- power supply voltage does not exceed 17 V.
If any of three first mentioned conditions is not met, unit remains in stand-by mode.
The PA is provided with a forced air cooling system and is protected against load mismatch, overheating and
overvoltage. The load mismatch protection smoothly reduces output power as the load VSWR increases above
2:1.
Three LED on the front panel indicate the unit status. The green LED “TX” shows that the output power is
between the nominal (>30 W) and minimum set power ( ~20 W). The red LED “G/F” (general fault) turns on
during overheating or overvoltage. The red LED “VSWR” is active when the load VSWR is above 2:1.
The PA has three outputs (open collector) for remote status monitoring. In an alarm state, the level is pulled
low.
The Manufacturer's rated output power of this equipment is for single carrier operation. For situations when
multiple carrier signals are present, the rating would have to be reduced by 3.5 dB, especially where the output
signal is re-radiated and can cause interference to adjacent band users. This power reduction is to be by means
of input power or gain reduction and not by an attenuator at the output of the device.
3. Construction.
Unit is realized as a module – see Fig. 2.
There are at the front panel:
- RF connectors;
- Fan, which pushes the air across an internal heatsink;
- Status LED;
- Access hole to the power set potentiometer;
- Handle for moving the unit into/from a subrack;
- Four quick release fasteners for fastening the unit in a subrack.
Front panel dimensions are 5.585”(W) x 5.055”(H). The full length of PA does not exceed 8.2”.
The PA contains two PCB assemblies: the Main Board Assembly and the DC Connector Board Assembly.
The Main Board is placed inside a shielded compartment and is to the main chassis plate/heat spreader. The
heatsink is attached to the outer side of Main Plate, as well as the fan controlling thermal switch.
The Main Board contains RF circuitries and the majority of DC circuits. The DC Connector Board includes the
LED, power controlling potentiometer, a fan voltage regulator and three DC connectors. The control,
monitoring and supply lines between the Main Board Assembly and the DC Connector Board Assembly are
routed through feedthrough filters, screwed into the Main Plate and are connected through an 8-wire cable and
two pairs of connectors (6-pin and 3-pin on the cable end, and 6-pin and 4-pin in the DC Connector Board).
This allows the same cable to handle the two modes of operation (remote or local, depending on which pins are
connected.
3
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