5.5 Power Amplifier (PA)
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5.5.4 FS-2570T COMB board (05P0740)
This board combines the outputs from two identical PA boards to obtain 250 W.
The output impedance of PA is 50 ohms. The same current flows in primary and
secondary windings of T1 in opposite direction so the magnetic fluxes are cancelled. No
current flows through R1 when PA outputs are the same.
T1 works as 4:1 impedance converter that is the impedance of the secondary winding is
25 ohms.
T2 converts the impedance from 25 ohms to 50 ohms. The output from COMB board is
connected to TX FIL board.
CHECK signal is used to indicate the test result of COMB board.
Fig.5.5.5 Block diagram of FS-2570 COMB Board
Fig.5.5.6 Frequency characteristic of DRV, PA and COMB boards
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