User Manual

5 Ch. VHF Radio Repeater Equipment
Document Number 50-189201HBK – Issue 1 Page 7 of 48
3. EQUIPMENT OVERVIEW
5 channel radio repeater 50-189201 is supplied in three 43U equipment mounting racks.
Rack 1 (50-189212) houses the main amplification modules along with the various splitters and
combiners.
Rack 2 (50-189213) houses the Cavity FIlters for the TX (Downlink) path
Rack 3 (50-189214) houses the Cavity FIlters for the RX (Uplink) path
Downlink.
Channel 1 – 154.190MHz
Channel 2 – 154.070MHz
Channel 3 – 158.910MHz
Channel 4 – 155.700MHz
Channel 5 – 158.850 MHz
The input splitter shelf (50-189207) receives Downlink VHF signals from the off-air RX antenna and
the signal is split and passed through a series of bandpass and crystal filters. The resultant five signal
paths then leave the shelf, each path going to the downlink section of a dedicated amplifier shelf
(BDA VHF Channel Shelves 1 to 5, 50-189202/06); these amplifier shelves also contain channel
selective modules to achieve the narrow bandwidth required.
Upon leaving the Amplifier shelves the five signal paths enter BDA VHF Downlink Output Combiner
(50-189208) where the five separate signal paths are combined into three. The three signal paths are
then fed into the cavity combiner in Rack 2 where they are combined into a single signal path before
being fed into BDA VHF DAS Hybrid Splitter/Combiner (50-189211) where the signal path is split into
two feeds, one for each LCX feed
Uplink
Channel 1 – 156.195MHz
Channel 2 – 155.325MHz
Channel 3 – 154.785MHz
Channel 4 – 154.830MHz
Channel 5 – 156.150 MHz
Uplink signals from the LCX are fed into BDA VHF DAS Hybrid Splitter/Combiner (50-189211) where
they are combined into a single signal path and passed into the first stage of the cavity filter in Rack
3. In the first stage cavity filter the signal path is split into three and each path passes through a cavity
filtering section and the three signal paths then are fed into the BDA VHF Uplink Input Splitter (50-
189210) in Rack 1, here the three paths are split into five and each path pases through a crystal filter
which passes the channel required.
Upon leaving the BDA VHF Uplink Input Splitter, each of the five signal paths is fed into the uplink
section of a dedicated amplifier shelf (BDA VHF Channel Shelves 1 to 5, 50-189202/06); these
amplifier shelves also contain channel selective modules to achieve the narrow bandwidth required.
From the amplifier shelves the five signal paths are fed into the Uplink Output Combiner (50-189209)
where the five signal paths are combined into three path before being fed into the second stage of the
cavity filter in Rack 3. After passing through the cavity filters the separate signal paths are combined
into a single path whis passes through a bandpass filter before being fed to the TX antenna