hello mr franco.thank you very much for helping me. i found the problem. for power supply use a 13.5 volt power supply and then i connect a step down for 12 volt. as soon as I put the power supply with 13.5 volts without the step down the problem was solved.. in the garden test and in the field I used a 18650 battery with a step up to have 12 volts. that must be the problem.. but the signal in the garden was very good and clear... as i had it before but in the field nothing is heard. i will do the circuit with the 78012 and see what happens... again thanks a lot.
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