TMA2Q/LPC2Q Quadrature Tower Mounted Amplifier Instruction Manual
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Figure 3 ~ Typical transmission loss (s21) for circuit “CW” and circuit “CCW” from 10 to 1000 MHz. See note.
Note to figure 3: Transmission losses shown above are typical and include the internal cables. Expect variations due to
component tolerances. Measurements were made using a vector network analyzer under the following conditions after 30
minute warm-up period at room temperature:
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Coaxial cable between VNA port 1 and TMA2Q RF Input: LMR-400UF, 1.22 m long
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Coaxial cable between LPC2Q RF Inputs/dc and TMA2Q RF Outputs/dc: LMR-400UF, 0.46 m long
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Coaxial cable between LPC2Q RF Output and VNA port 2: LMR-400UF, 1.22 m long
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Unused circuit ports terminated with 50 ohm terminations
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VNA output level –30 dBm and frequency range 10 to 1000 MHz
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Markers: 10, 50, 100, 500 and 1000 MHz
At lower frequencies, the system gain is nominally the same as indicated in the amplifier datasheet less splitting
losses through the quadrature coupler of approximately 3.5 to 4.5 dB. At higher frequencies there are additional
implementation losses due to the interconnecting cables and the two bias-tees in each circuit. Where longer
interconnecting cables are used, the gain will be less than shown in the plot and will roll off more at higher
frequencies.
Caution
: Do not attempt to use the TMA2Q/LPC2Q without all RF connections. These include 1) two circuit
connections between a cross-polarized antenna covering 50...500 MHz and the TMA2Q RF IN, 2) two circuit
connections between the TMA2Q RF OUT and LPC2Q RF IN, and 3) two circuit connections between the LPC2Q
RF OUT and two receivers RF IN.
C.
TMA2Q Tower Mounted Amplifier Installation
Caution
: The TMA2Q may be partially disassembled for shipment. If so, a paper warning flag will be inserted in
the TMA2Q cover. In this case, the TMA2Q will require final assembly before testing and installation. See
Appendix A. Whether or not any final assembly is required, the TMA2Q cover should be removed and the
internal area inspected for shipping damage or loose cables. Prior to shipping all connections are properly
torqued; DO NOT re-torque unless the connectors are found to be loose.
Caution
: Connect transmission lines at the TMA2Q before connecting them to the LPC2Q, and before connecting
at the TMA2Q momentarily short the center contact of the cable connector to the shell to dissipate any static
build-up in the cable. Never apply a short to the cable if it is connected to the LPC2Q and the LPC2Q power is
turned on.
Caution
: To minimize transient voltages on active components in the TMA2Q and LPC2Q assemblies and to
prevent accidental opening of the overcurrent protection circuits in the LPC2Q, DO NOT apply power to the
LPC2Q until all transmission line connections have been made between the TMA2Q and LPC2Q.
Caution
: Only the LPC2Q is equipped with reverse polarity protection for the two internal power supplies; the
TMA2Q power supplies are not equipped with reverse polarity protection. Do not connect anything to the
TMA2Q RF dc port unless its polarity and voltage are known to be correct. The TMA2Q maximum input
voltage is 8.0 Vdc with the center conductor of the coaxial power connector positive polarity with respect to the
connector shell.
