2019年11月29日 · There must be a strong interference that was driving the SA612 to saturation. Initially, I thought the noise was coming from the switiched-mode power supply, so I powered the Raspberry Pi from a benchtop linear power supply, and I also powered the SA612 mixer from a 9-volt battery instead. See the following block diagram. But it had little effect.

2020年9月6日 · I tried to use SA612 as a frequency mixer. Since it's a Gilbert cell, it has a high input impedance. Thus I added a pair of transformers as "Experimental Methods in RF Design" book suggests: The mixer seems to work:

2016年10月22日 · You may find the SA612 chip more readily available than SA602. I believe the SA602 is an identical chip with slightly tighter specs than SA612. SA612 is pin-compatible replacement. As for the LM387 (IC2) low-noise preamp - you might substitute a two-transistor amplifier instead, shown below.

2021年11月10日 · I downloaded a 2-meter receiver schematic using an IC for the dual conversion IF strip. The first 10.7MHz IF uses a crystal filter with a terminating impedance of 1800//5pF.

2024年12月9日 · You could build this with 8 or 9 discrete matched transistors, or transistors all from the same batch. A PCB rather than breadboard. Biasing requires many resistors (a pain). SA612 is a Gilbert-cell alternative chip with all the internal biasing done for you. $\endgroup$ –

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DIY SA612 + RTL-SDR HF receiver: good on laptop, but huge wideband noise on Raspberry Pi. 2. Reducing ...

2024年4月2日 · For example, an SA612 mixer has two 1500-ohm outputs on pin 4,5 that are out-of-phase. One drives the crystal, while the other drives the compensation capacitor. As with all bridges, some adjustability should be provided - perhaps the 3.5pf capacitor should be variable.

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2021年5月18日 · I’m trying to locate the source of some interference on the FM band — it’s audible as 3 quick staccato bursts of brownish noise approximately every 3.5 seconds.