User Manual

Axell Wireless Limited
Technical Literature
15 Channel UHF Hybrid Select Repeater
Document Number 50-157401HBK Issue No. 1 Date 26/03/2008 Page 38 of 50
4.7. Uplink 5W Amplifier Shelf 50-157406
There are three 5W Amplifier Shelves in this system (one for each of the three Uplink Channels.);
each Amplifier is housed in a 3U, 19” Rack Mount Tray.
The three channels are as follows
Channel 1 is 412.950 to 413.650MHz
Channel 2 is 415.880 to 417.200MHz
Channel 3 is 419.050 to 420.000MHz
The uplink signal enters the 5W Amplifier shelf from the Splitting Duplexer 50-157405 via the
uppermost “N” type port on the back and then passes through the first of three amplification stages;
the first amplification stage is provided by a Low Noise Amplifier (11-007402) which provides 30dB of
gain.
After the first stage of amplification the signal then passes through a Switched Attenuator (10-000701)
which provides up to 20dB of signal attenuation in 2dB steps; the setting switches for this Attenuator
are accessed on the back panel of the shelf.
After leaving the Attenuator the signal then passes into the second stage of Amplification, this is
provided by a second Low Noise Amplifier (11-007402) providing a further 30dB of gain. The signal
then passes through a Bandpass Filter (02-007309) which is tuned to the required passband
frequency and rejects out-of-band noise.
After the Bandpass Filter the signal enters the third stage of Amplification which is provided by a 5W
Power Amplifier (12-021601). The second and third stages of amplification are straddled by an
Automatic Gain Control assembly (17-019802 and 17-016401) which provides further signal
attenuation if needed. The signal then exits the 5W Amplifier shelf to go to the Combining Duplexer
50-157405 via the lowermost “N” type port on the back.