Eugen_E
Full Member level 6
sdr noise
I've finished building the control board and frequency synthesis board for an HF SDR receiver (3 - 4MHz).
The synthesis drives an I/Q sampling detector, producing an AF signal, which is amplified and applied to a PC soundcard for software demodulation.
For testing, I built a sampling detector with the 74HC4053 switch, and an AF amplifier (+30dB) with the LM833 opamp.
The problem is, the noise level on the AF output it's very high, about 30mV peak, even without the antenna. With such high noise level, I can receive only very powerfull stations, so the receiver can't be used. When I remove the 74HC4053 from socket, the noise dissapears.
What could be the cause for the noise and what can I do to reduce it? I need to use 74HC4053, because I test the circuit on proto-board.
If you know a good configuration with 74HC4053 as sampling detector, please post it.
I've finished building the control board and frequency synthesis board for an HF SDR receiver (3 - 4MHz).
The synthesis drives an I/Q sampling detector, producing an AF signal, which is amplified and applied to a PC soundcard for software demodulation.
For testing, I built a sampling detector with the 74HC4053 switch, and an AF amplifier (+30dB) with the LM833 opamp.
The problem is, the noise level on the AF output it's very high, about 30mV peak, even without the antenna. With such high noise level, I can receive only very powerfull stations, so the receiver can't be used. When I remove the 74HC4053 from socket, the noise dissapears.
What could be the cause for the noise and what can I do to reduce it? I need to use 74HC4053, because I test the circuit on proto-board.
If you know a good configuration with 74HC4053 as sampling detector, please post it.