| Electronics > Projects, Designs, and Technical Stuff |
| AM RF rejection - how to help needed |
| (1/1) |
| AllTheGearNoIdea:
Although my main interest is collecting and repairing test equipment I do on occasions dabble in radio repair. I would like to do some before and after testing and see how a particular radio compares to the manufacturer’s specifications. If you cannot measure it how do you know you have made an improvement etc. I’m today playing with a fairly typical domestic receiver of the 60s and 70s and need some practical advice on how to test the AM rejection against manufacturer’s specifications sheet. The radio specifications quotes” 40db {Signal to noise ratio greater than 50db} My IF is 470khz. Having tuned in the radio to the signal generator do I then increase the frequency off generator by 2 x IF and make measurement with the modulation on and off to get the signal to noise ratio. Where do I make the measurement I am guessing it could be at the output of either the IF stage or speaker dummy load. I should keep the signal level very low to avoid activating the ALC ? Is the 40db part of the specifications telling me the amplitude of the image Frequency should be 40db down on the level at the frequency the radio is tuned too. I have never done this before so just need some help with the basic setup and getting the procedure correct. I do have basic test gear including RF test sets. Thanks regards Chris |
| iMo:
FYI https://archive.org/details/PracticalRadioFrequencyTestAndMeasurement/page/n197/mode/2up |
| Navigation |
| Message Index |