Re: BFU590 strange behavior
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The BFU590 has an ft of 8.5 GHz.? The 2N2222 has an ft of 300 MHz.? Chances are highly likely the BFU is oscillating.? Try installing a non-inductive 33 or 47 ohm resistor in series with the collector.? What's more, an 8.5 GHz device is almost assured of oscillation when placed directly in the circuit of the 2N2222.?
Dave - W?LEV
On Sun, Sep 29, 2024 at 2:35?PM Francesco Caizzi via <netsmo62= [email protected]> wrote: Good morning, I wanted to tell you about a problem I'm having with the BFU590s (assuming they are) with which I made a replica of the ALA1530. The one I've used so far has always worked well but it uses PN2222. I then made a second version but with BFUs instead of PNs. The BFUs are marked "S59 W42" and I got them on the Italian TME ecommerce platform () and not on Aliexpress or some China page on Ebay. In practice it is impossible to calibrate the 100 ohm trimmer to 0 volts, the absorption always tends to rise, sometimes 140 mA, then it goes to 170 or worse, sometimes then it drops to 160-150 then rise again... and in any case the amplifier doesn't work. There is no point in trying to calibrate it even finely, sometimes I see the voltmeter pointer vary on its own (self-oscillations?). The rest of the circuit is built exactly like the version with PNs, same values ??and everything has already been verified several times. If you have any suggestions for me, I would be grateful. Greetings, F.
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