Complete Exciter 50W with MPX generator and audio limiter

Front side of transmitter. In this box is PLL (Phase Locked Loop) control 85-115 MHZ, RF out, power supply, stereo coder and audio limiter. On the left are instruments for VU levels, audio inputs and controls, in the middle frequency counter and at the right PWR / SWR meter, output control and RF out.

Top view with space for cooling.

Rear view, fan, fuse and current connector.

Inside the exciter, at the left, MPX (vertical) and VCO PLL control. (This photo is made before exciter was equipped with limiter). In the middle transformer 350W, 220V filter, at the right voltage stabilizer and broadband RF out with BLY87 and BLW60.

VCO + PLL control unit. RF out is less than 1W.

Coder

This is the last gadget I used for pirate radio broadcasting, and the transmitter works great. Parts used are partly factory constructions and partly custom made. It’s fully broadband, and covers the whole band from 87.50 – 108.00 MHz, in increments of 100 KHz, which may be its only shortcoming in comparison with much more expensive highly professional units, although this shortcoming is evident only in conditions of bands dense "population" with strong signals. The broadband amplifier gives 0 – MAX (variable) of output power with spurious / harmonic suppression better than 60dB. Output connector is N type. Frequency stability is +- 100Hz. Stereo separation is better than 45dB and signal to noise ratio is better than 75 dB.

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