Homebrew AM transmitter
 

http://i390.photobucket.com/albums/o...ia/GLRy098.jpg

The schematic

http://i390.photobucket.com/albums/o...nia/sender.jpg


Any tubes..any transformers that comes from an old radio can be used in this transmitter..its not critical.

The coil can be made by any wire..no need for litze...a calculator ( http://www.pronine.ca/coilcal.htm ) allow you to make the coil as you like...the feed back is one forth of the turns. I am not saying this is the ultimate transmitter...however the sound is great...depending of the OPT (T1). Don't worry about the OPT impedance as its not connectet to a loudspeaker...however you can connect a loudspeaker as a controle monitor..but use a resistor least 27 ohm or its going to be loud.

Range...some hundred meters...definitely not legal.

Voltage before 'L3' approx 200V...just like an *old radio*...ATT. R13 180ohm or less,C11-12...2,2nF 600V

The magic eye and the mic is only an option....over-modulaton causes sparks in the tuning-capacitor...just like a real transmitter.

In spite of its simplicity it makes no noticeable FM modulation...

Hey pretty cool. :cool: Looks like the oscillator is 'shunt modulated' by the AF out stage. Does it have an antenna, or just xmit by spurious radiation? What is the function of the V4 triode?

Its plate modulated...V4 ECC32...(one half for any purpose). It use the powerline as antenna (plug&play)...the filter C11, L6, C12 allow RF and prevent AC to enter the oscillator.

Interesting....I wonder if I could duplicate that circuit with hearing aid subminiture tubes.