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AM modulator with MC1496 project problem

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tzitzikas

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Hello, i have done this project. It is an experimental oscillator - modulator for mw frequencies. The schematics are here:
oscillator:
https://tzitzikas.webs.com/oscillator-1.JPG
modulator:
https://tzitzikas.webs.com/modulator-1.jpg

The problem is that the designer told me to use an 1kohm variable series resistance between oscillator and modulator (after c9=22n capacitor of oscillator) to adjust the carrier level. I saw that the 1kohm variable series resistance is not enought because with 1kohm series resistance the audio was't very good. I think that the carrier level was high. So i change this resistance with another 4.7kohm. Now i am using about 2kohm of this series resistance. The modulation is very good But i think that the audio signal in the radio is not at the center of the frequency but a little above.
(The operation frequency is 1000khz but i listen the audio with quality and strong voice at 1003khz.)
which is the problem? how i can fix it, to listen the audio very well at center frequency and not at sideband?
Thank you.
 
Hello, i have done this project. It is an experimental oscillator - modulator for mw frequencies. The schematics are here:
oscillator:
https://tzitzikas.webs.com/oscillator-1.JPG
modulator:
https://tzitzikas.webs.com/modulator-1.jpg

The problem is that the designer told me to use an 1kohm variable series resistance between oscillator and modulator (after c9=22n capacitor of oscillator) to adjust the carrier level. I saw that the 1kohm variable series resistance is not enought because with 1kohm series resistance the audio was't very good. I think that the carrier level was high. So i change this resistance with another 4.7kohm. Now i am using about 2kohm of this series resistance. The modulation is very good But i think that the audio signal in the radio is not at the center of the frequency but a little above.
(The operation frequency is 1000khz but i listen the audio with quality and strong voice at 1003khz.)
which is the problem? how i can fix it, to listen the audio very well at center frequency and not at sideband?
Thank you.
The 1496 is a balanced modulator so there is no carrier frequency, just upper and lower sideband so your two output frequencies are 1001khz and 999khz.
 
The mc1496 in my case is working as an am modulator. i think the channels for sideband frequencies are 5khz. Anyway my radio receiver is analog. i have test it with many analog radio receivers and the modulation is not in the center of frequency. i have test it also with digital radio. but the digital radios here in Europe have 9khz channels so i can't listen the sound at the frequencies a little above the center frequencies.
Do you have any idea why?
 
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