User Manual

INSTALLATION AND MAINTENANCE MANUAL
LYNX.sc E1 FAMILY
SPREAD SPECTRUM RADIOS
OCTOBER 1998
SECTION 3: INSTALLATION & ADJUSTMENTS PAGE 3-39
3.13.1 Output Power Adjustment
The LYNX.sc radio requires professional installation. In certain cases, it is necessary to adjust the
output power from the factory setting, for example:
❖ to meet EIRP (effective isotropic radiated power) limits, such as +6 dBW in Canada.
❖ to meet transmitter output limits in the 2.4 GHz band for USA installations.
❖ to avoid exceeding the maximum far-end RSL of 0 dBm.
❖ to coordinate a hub or repeater location.
To ensure maximum protection of the radio circuits, always
ensure the antenna connector is terminated when power is
applied.
For precise measurement of transmitter power, a calibrated RF power meter (such as the HP
435B with Power Sensor HP8481) is recommended. This power sensor can be connected directly
to the output of the radio without exceeding the power rating. With some power meters, it may be
necessary to place a calibrated in-line fixed attenuator between the radio antenna port and the
power meter so as to not exceed the power meter’s maximum input level. Thruline power meters
do not operate at LYNX.sc RF frequencies.
If adjusting the output power to meet an EIRP limit, it will be first necessary to calculate the overall
system gains and losses, including feeder losses for the type of transmission line installed and the
antenna gain. Also refer to Table 3-C or 3-D for transmitter output power settings where installed
with various transmission line lengths and antenna sizes. You may determine the radio transmit
power for EIRP limited installations by the following equation:
Tx Power (dBm) = EIRP Limit(dBm) + Feeder Loss(dB) - Antenna Gain(dB)
In the USA, 2.4 GHz models have an output limit which is determined by:
Tx Power (dBm) = 30 - [(Antenna Gain - 6)/ 3] + Feeder Loss
Output power may be adjusted using a small screwdriver and rotating the potentiometer which is
recessed behind the front panel. Clockwise rotation increases output power while counter-
clockwise rotation decreases output power.
In lieu of a calibrated RF power meter, the PWR test port voltage can be used to estimate the
output power. Figures 3-16 & 3-17 illustrate the voltage reading for various output power levels.
The factory test data sheet should be used to establish a more precise setting of this adjustment.
After setting the correct output power, place the cover cap
found in the installation accessory kit over the front panel
receptacle.