Low Power AM Transmitter (Phono Oscillator) A phono oscillator is simply a low power AM transmitter, operating in the MW broadcast band. The "Phono Oscillator" goes back to the 1930's where the audio signal from a phonograph pickup, is used to modulate a low power medium wave oscillator, the radiated signal which can then be received on a broadcast radio in the near vicinity. The name is derived from "phonograph oscillator." This is a "proof of concept" construct: a build essentially to see, how well it functions. All componentry was sourced from recyclables found in my workshop! I used a russian 6J10B-V 'pencil' tube (triode connected) as audio pre-amp As previously utilized in minature oscilloscope project (scroll down) A 6BE6 pentagrid (frequency changer) is the modulated oscillator (phono-osc) HT supply line is regulated by an 0B2 voltage regulator (+108 volt DC) Oscillator grid current is measured on d'arsonval meter (1mA FSD) Oscillator coil is wound on small salvaged ferrite bobbin. A calculation gave 155uH as the required inductance 75 turns gave this inductance, which I then measured on my LC meter. Cathode (feedback) winding is 33% (25 turns) of main winding Winding polarity must be observed to ensure oscillation (red dots) A small 320pF variable capacitor gives tuning over the frequency band (0.5 ~ 1.5MHz) The modulation pot' is advanced so the volume is similar as other AM bcst stations. My circuit is based on an example from cool386 found at: Low Power AM Transmitter. © 3Q 2018