| 摘要 |
Transmitters, particularly shortwave transmitters, for transmitting voice and data must meet high requirements for the linearity of their characteristics. Since the transmitter output stages used cannot meet these requirements for the linearity, particularly when they are constructed in the form of wide-band transistor power amplifiers, a filter arrangement is provided at the output end of the transmitter output amplifier, the suboctave filters of which, allocated to different frequency subranges, can be inserted optionally into the connecting path between the output of the transmitter output amplifier and the antenna for suppressing unwanted harmonics. To reduce the production expenditure in manufacturing such filter arrangements, it is proposed to build up the filter arrangement by means of resonant-circuit modules (SK) which are in each case separately calibrated for their nominal frequency with the aid of a calibrating device (O, AD, FZ, SV) before they are inserted and soldered to the circuit board (LP) common to the modules. <IMAGE>
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