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sa612an noise, is that really that noisy?

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neazoi

neazoi

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Hi I have connected an sa612 with a 6v battery and a shunt 100nF. This is followed by a small amplified speaker.
The noise out of this chip even if no external local oscillator is connected to it and even if no antenna is connected to it, is huge. I have verified that the noise is not from the amplified speaker.
So it is an sa612an that is not connected to anywhere else than the amplified speaker and the PSU.
What am I doing wrong?
If you need more info let me know.
 

You can't judge it like that, at least shunt the LO and signal inputs with a resistor to match the expected impedances.

Brian.
 
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    neazoi

    neazoi

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betwixt said:
You can't judge it like that, at least shunt the LO and signal inputs with a resistor to match the expected impedances.

Brian.
Click to expand...
I left them unconnected, should I shunt them?
I notice a reduction in noise in higher input voltage 8-9v.
Maybe it is something with the PSU. It is a pitty cause the lm386 is proved to have low noise even with a gain of 20.
So how can I cope with it?
 

Leaving the inputs floating is probably the worst case for producing noise. Normally they are driven by low impedance signal amplifiers or the LO. To get a more realistic noise appraisal, try temporarily connecting each of pins 1, 2, 6 and 7 to ground through 100nF capacitors and see what change it makes.

Brian.
 
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