Hi all,
I was working on an old AM radio and I started wondering how you could calculate the gain of a true common-emitter BJT whose collector was connected to an IF transformer (turns ratio 57/7). The impedance seen by the secondary is about 2K so primary impedance should be roughly 49K ohms. Anyone know the formula or a procedure?

 

Approx : Rc/ (re+Re). The emitter is bypassed? Rc is primary impedance

Also, please why is the primary impedance 49k?

 

This page has a Block diagram of a superheterodyne receiver
http://www.electronixandmore.com/resources/amradio/index.html
The IF amplifier sometimes 455 kHz the primary can be tapped might include a parallel capacitor.
The IF transformer having different configurations. Narrow it down either schematic or more information. yellow dot, part number, size
Maybe this radio is earlier and not have a standard IF at all. Early radios had moveable coil adjustment.
Possibly it will be easier like one of these:
https://lucsmall.com/2013/05/10/am-superhet-radio/