It can deliver up to 25 watts of RMS power into a very short length aerial,

This equates to 100 watts peak power cleanly driven up to 100% modulation.

The signal does tail off at lower frequencies due to inefficiencies of the output coil.

This transmitter has been designed to operate into a reasonably short ‘long-wire’ aerial, minimum length approximately 5 metres and up to 20 metres. The design therefore makes it easy to tune and operate. The higher the aerial, the further the range will be. Therefore, you must put the transmitter at the aerial feed point. No Coax MUST NOT be used.

Although the unit comes with a 24 volt power pack, it is advised that you use a bench style DC power supply capable of delivering up to 4 amps at up to 25v. At certain frequencies the unit will draw a heavier load from the power supply, but so long as the current does not draw any more than 3.4A the output will not be distorted, as the output transistor is reaching its limit of ‘safe operation’.  At lower frequency operation the transmitter does draw more current. At 882KHz and lower, the supply voltage must be reduced to 17volts as the current draw is higher the lower in frequency it goes.  Therefore, the supply volts can be varied to avoid an overload situation. (at 1224KHz into my 10 Metre aerial, the transmitter is happy at 3.4A with 20v DC. Any more voltage and it distorts)

The Transmitter circuit design uses a CMOS oscillator in a Phase-locked loop circuit for accuracy and ease of frequency selection.  It is very stable and therefore does not drift off frequency. The Phase Lock circuit provides selection in 9KHz steps, so that the unit can be used in the UK or Europe, for the 9KHz spacing between channels.

For use in the USA and other parts of the World where 10kHz is used between channels a different Crystal will be fitted as requested. A rugged Power MOSFET is also used on the RF output stage, which drives the output toroid and variable tuning capacitor. High voltage rated components are used in the output section.

Audio modulation is series-derived using a Power Transistor. It is driven by low level amplification. A CD player, mixer, PC etc plugs directly into the RCA audio sockets on the rear. Audio Modulation level is adjusted by the internal trimmer VR2.

The transmitter is housed in a Steel box with ABS front and rear panels.

Ventilation holes to improve air flow for component cooling. Two fans are used on this model, one for the Modulator and the other is used to force cool the output RF Mosfet and output coil.