Well, I have recently composed a radio using CXA1019S(a product of Sony),However, the radio cannot receive the FM signals(It accually receives the noise), thought I have examed all the solder points and they are all well soldered. Please give me some suggestions on how to quickly exam where was wrong. If not, as a amateur, please tell me the detailed methods to find the wrong area.(the tools that I only have are an oscillograph and a multimeter) Thank you for your help!,I am really anxious.
Thank you for your Help!!
Nov 29, 2007
1 Replies
If you are trying to receive FM signals in the 88-108 MHz range, then be aware that the oscillator in your circuit must mix with the incoming signal to produce a difference of 10.7 MHz. Thus, you can use a working FM receiver to determine if the oscillator is working. For example, if the non-working receiver is set to 90 MHz, then the oscillator should be 10.7 MHz higher in frequency (100.7 MHz) and you can tune to that frequency with the working receiver placed close by to determine if that signal is present. The working receiver will show some activity such as quieting or a "dead carrier" if the signal is present.
Your oscilloscope might not be capable of displaying the oscillator signal or might load the circuit and prevent oscillations.
Google for "superheterodyne" to get more information.
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