User's Manual

8
10.0 Operation
The unit operates automatically and there are no user adjustments required.
The amplifier is only intended for use with 2.4 GHz radio modems that alternate between
transmit and receive in the same radio channel. These are referred to as Time Division
Dultiplex (TDD) devices. A typical example is an 802.11 WLAN card or Access Point. These
modems “ping-pong” back and forth between transmit and receive so quickly during normal
operation that both the TX and RX LEDs will appear to be lit simultaneously. In fact, they are
turning on and off so quickly that they appear to be on all the time. You can tell the duty cycle of
one of these LEDs by their brightness.
The amplifier will not work with radio modems or wireless bridges that are band-split true full
duplex devices.
The amplifier provides for linear amplification for transmit output powers up to at least 400 mW.
This is important for Direct Sequence Spread Spectrum (DSSS) radios, especially 802.11
devices. If you drive the amplifier so hard as to exceed the rated output power, the amplifier will
start to go into compression. This will result in raising the sidebands and create interference on
adjacent radio channels. The FCC Certification for this amplifier is for +24 dBm (250 mW)
output, which requires the input to not exceed +10 dBm (10 mW).
For Frequency Hopping Spread Spectrum radio devices, versions of the amplifier are available
that have the output power limited to 250, 400 or 500 mW as specified in the FCC certified
system. These amplifiers should not be used with DSSS radios since the transmit power
limiting mechanism in the amplifier will cause it to go into compression when their respective
clamped output levels are reached.
11.0 Typical Amplifier Installation Details
The diagram that follows on the next page illustrates the typical AMP2440 amplifier installation.