User's Manual

Doc. No.
Rev.
Date
1.00
2011-12-08
Damm Cellular Systems A/S, Denmark
TETRAFLEX
®
V7.5 MANUAL - TX Combiner for BS41x
TetraFlex® 7.5 Manual 4-12
The TC411 module contains 4 cavity filters, which are internally combined together with a 4-
way ¼-lambda junction, which transforms the short circuit of the cavity at out-of-band
frequencies to open circuit at the junction point.
4.2.2.3 Junction cables
The TC411 combiner module can either be connected directly to the TF411 filter or expanded
with junction cables to 8 channels (optionally up to 16 channels). The junction cables are ½-
lambda (or multiply thereof) long in order to keep the high impedance for all out-band
frequencies in all junction points.
The junction cables are manufactured with extremely high precision and measured
individually for electrical length. Never try to create these cables on your own.
4.2.2.4 Filter connection cable
The combiner output from the junction point is connected to the TF411 TX output filter with a
cable with a specific electrical length. The electrical length is important for out-band
frequencies due to the serial connection of two filters.
4.2.2.5 TX output filter
The TF411 high-power TX output filter gives an additional rejection of the TX noise of 25dB in
the RX frequency band, which together with the cavity filters gives a total RX band rejection
of 60dB minimum.
The output connector of the filter is a DIN 7/16mm connector with good inter-modulation
properties.
The filter output also contains two directional couplers with BNC connectors with an
accurately adjusted coupling of -40dB and a directivity of minimum 25dB.