4

I think I figured this out. By looking at VFO with an oscilloscope I could catch a brief glitch (~1.5ms) in the signal when the frequency is changed: It was hard to notice because you can't easily trigger on this. I had to manually trigger single captures while tuning for some time to see this. Then by googling "si5351 output glitches" I've found ...


3

Try powering the LM386 temporarily off a battery. if the popping stops, then the cause is a surge being conducted into the 386 from the supply that feeds the rest of your circuit. Normally, you would bypass the power input of the 386 to ground with a hefty electrolytic capacitor (50 to 100mfd) and then shunt that with a fast-acting cap (0.01 to 0.1uF) to ...


2

This is a basic question and needs an answer. Regenerative receiver or audion. Single LC-filter with undamping: Q-multiplier. The frequency transfer of such a filter can be obtained from a simulation. See figure. As you can see: the AM demodulated audio response is affected when selectivity is too high. The example shows 1 MHz mediumwave. Audio bandwidth of ...


1

Since it happens when switching frequencies, I suspect glitches of some form in the local or beat frequency oscillators' output. The mixers simply multiply the "signal" by the oscillator. Any noise or glitch in the oscillator outputs will be reflected in the mixed outputs. You may be more sensitive to BFO glitches, since the output is at DC, not a ...


Only top voted, non community-wiki answers of a minimum length are eligible