Bandwidth is called the range of frequency which is passed pyezofiltry or the filter of the concentrated selection. The selectivity of the last on adjacent channel depends on the bandwidth of the filter of intermediate frequency installed in the radio receiver.
Instruction
1. Cut off power the radio receiver and discharge accumulative condensers of its power supply.
2. Disconnect an entrance and an exit of a pyezofiltr or the filter of the concentrated selectionsfrom othersknotsreceiver . To the entrance connect the generator of standard signals (parallel to it it is desirable to attach a frequency meter), and to an exit - millivoltmetr with a detector head. On the generator previously establish amplitude of an output signal about 0.5 V.
3. Learn value of intermediate frequency of the receiver from documentation to it or from designations on filters. Intermediate frequency of a path of AM is usually equal in modern devices 450, 455, 460 or 465 kHz, and a path of a WC - 10.7 MHz. In old designs values of intermediate frequency of a path of a WC, components 8.4 or 6.5 MHz meet.
4. Establish the frequency of the intermediate frequency of the receiver about 20 percent lower than rated value on the generator. Smoothly rotate the handle towards increase in frequency. Notice the moment when indications of a millivoltmetr sharply increase. Write down for what frequency at the same time the generator is ready. Recognize it by a scale of the generator or, in the presence of a frequency meter - by its indications (they more precisely). It is the lower bound of bandwidth.
5. Continue to increase generator frequency. Notice the moment when indications of a millivoltmetr sharply fall. The same way define the upper bound of bandwidth.
6. If necessary calculate strip width, having subtracted its lower bound from top.
7. In determination of bandwidth the device consisting of the generator of the shaking frequency, the generator of tags and an oscillograph can provide substantial assistance. Knowing what the difference of frequencies between the next tags on the screen is equal to, make a proportion and calculate width of the filter bandwidth shown on the same screen. This device allows to observe also a form of borders of a strip (whether recessions smooth or sharp are).
8. After the end of an experiment power off all devices, disconnect them, and attach the filter back to other elements of the receiver.