Timeline for What is the reason behind the wiring of the IF tapped transformers in these AM superheterodyne receivers?
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 2, 2021 at 21:23 | vote | accept | Dag | ||
| Aug 23, 2021 at 15:45 | comment | added | user16324 | That's right ... pin 1 is GND (to AC, via C19) and you're applying a voltage across pins 1,2 and seeing a higher voltage across 1,3. Note that Q2 collector is a fairly high impedance so the step-up ratio need not be remotely as high as in the LO. | |
| Aug 23, 2021 at 15:42 | comment | added | Dag | The only thing is, I'm not really sure I visualize how is it possible to correctly filter the signal in the second case: if the resonant frequency is obtained from the parallel of the first coil and the internal cap, shouldn't the signal be "injected" at one end of the whole coil? Or maybe it works because of the first coil acting as an autotransformer, and so when the signal is presented at the center tap, it will also be present at the whole coil (scaled up or down according to the ratio)? | |
| Aug 23, 2021 at 15:42 | comment | added | Dag | Thank you for the answer! So, correct me if I'm wrong: what you are saying is, both the examples refer to the same "strategy" of stepping up the impedance (from the emitter in the first case / from the collector in the second case) so that the resonator sees the biggest impedance possible in order to avoid "draining" it (because it would lower its effectiveness) [continues...] | |
| Aug 23, 2021 at 14:02 | history | answered | user16324 | CC BY-SA 4.0 |