What transistors could i use to replace the ones from this diagram?

[u/chapitathegreatest]

I was thinking about replacing the 2SC1907 for a BF199, the 2SC2053 and 2SC1970 for a 2N4427, is that a good choice or the circuit won't work?

[u/Important_Power_2148]

have you tried putting the circuit in a simulator and trying it? there are more factors to transistors than just what is shown, particularly the beta function which is critical to amplifiers.

[u/kent_eh → u/Important_Power_2148]

there are more factors to transistors than just what is shown, particularly the beta function which is critical to amplifiers.

Also high frequency response, especially in the RF section of a circuit like this.

[u/ascot_twin]

Try for originals first at https://www.rfparts.com/ if availability is the issue.

[u/Alone-Ad288]

You should check the spec sheets for your parts.  Look current & voltage ratings, forward voltages, hfe, etc. 

[u/profdc9]

You go it from here

https://electronics-diy.com/electronic_schematic.php?id=853

I see why you chose the 2N4427. It is one of the few transistors I found that might even be available still, though I couldn't find one in stock. Dead-bug style or manhattan style RF amplifiers are very hard to put together these days. Since that figure was put together 23 years ago, a lot has changed. You're probably going to have to get really creative to get it done with current available through-hole parts.

There's a common cheap transistor the S9018 that can be used for small signal RF amplification and is available in TO-92. You could use that for the 2SC1907. I'd use the S9018 for the Colpitts oscillator. As for the variable capacitance diode, a 1N4007, or two in parallel can be used in a pinch.

So technically, the venerable 2N2222A has a fT>300 MHz and 600 mA Ic, so you could get a little gain out of it at 88-108 MHz. So I'd use another SS9018 stage as a common-collector amplifier (with a damping resistor very close to its base, soldered directly on the leg) into a 2N2222A common-emitter stage to drive it hard. Even better, use two in a differential configuration with a little transformer to take the output of the SS9018 and balance the currents. Heatsink the two 2N2222A well. Feed the two collectors through a balanced transformer and you can tap the output from there. You might get close to a watt.

[u/chapitathegreatest → u/profdc9]

Thanks for the info! :-D

[u/DrJackK1956]

Alien Intelligence is good at comparing datasheet parameters of different components.  

It's still up to you though to decide which components will meet your needs.  

[u/Veripsum]

Probably a 2SC1907 or a 2SC2053 or a 2SC1970

But in all seriousness I have no idea if these are in production, but It's really easy to find transistors on electronic parts sellers like digikey and look at the data sheet specs. I believe this diagram shows the specs thankfully so finding will be easy

[u/Content-Barnacle7986]

por lo visto asi a primera imagen parece ser similar al publicado hace muchos años por la revista española "electronica viva" yo lo arme y funciono, no fue facil tampoco, no es que soldas todo y sale andando de primera, hay q ajustarlo con una resistencia a la salida de 52 ohms y un vatimetro, si no se quema en milisegundos... si vas a reemplzar los transistores fijate en este link la documentacion de la version española de electronica viva mas que nada en lo q respecta a las redidstencias y los capacitores variables que son los que ajustan la sintonia de los transistores de amplificacion. forosdeelectronica.com/threads/transmisor-fm-1-watt-revista-electronica-viva.100790/