The builder tells us that the audio input (modulator input) is able to accept a wide range of impedance and V P-to-P levels. including old school cassette players, MP3 players, the output from a PC sound card or mobile phone (you might need a ferrite cable clamp to reduce noise) or CD player.
Apparently you can connect a microphone pre-amplifier (the unit needs a bit more voltage than straight mic output) to transmit voice.
A 10W 60V RF power transistor is used at the output section to withstand high VSWR levels due to random type mismatched antennas.
The transmitters all operate on 12 Volts DC of varying ampere levels, depending on the output power of the specific unit.
And what power levels there are! These are definitely not Part 15 compliant so please keep that in mind.
- Covers most of the AM broadcast band
- Tunable on any desired frequency within it's coverage
- 2SC2014 power transistor as PA stage
- BD139 AF power transistor as modulator stage
- 2X 2N2222 transistors as oscillator
- 2N3904 transistor as high gain audio amplifier stage
- 2.5 Watt Tuneable AM Radio Transmitter for 800-1600 KHz - Operates on 12 Volts DC 450 mA
- 1.5 Watt Tuneable AM Radio Transmitter for 800-1200 KHz - Operates on 12 Volts DC 300-500 mA
- 0.5 Watt Tuneable AM Radio Transmitter for 800-1600 KHz - Operates on 12 Volts DC 150-200 mA
- 0.5 Watt Two Frequency AM Radio Transmitter for 1000 And 1500 KHz - Operates on 12 Volts DC 150-200 mA