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One of my projects those are least complicate to assemble. An antenna amplifier most important task is to compensate for the attenuation of the signal a long cable causes. There is no benefit to use it if the antenna is faulty constructed, obscured or deficient in some other way - except when the radio receiver not is sensitive enough. If the receiver has low sensitivity (cheap model) then a RF amplifier can be helpful. The 5V supply voltage is generated in the amplifier with LM340 and can by means of different resistance-configurations provide different gain values. The specifics for this kind of HF circuit is that the input and output impedance should be the same as the cable's impedance, which limits the amplifier's flexibility. 
AA755V is fed with a DC voltage higher than 7V through the antenna cable to the antenna amplifier. In order the voltage not shall cause any harm with the receiver must it be provided with a capacitor in the antenna socket, which blocks the DC voltage. If you want to look closer on this thing you can download it here: In the zip-file can you find everything required to implement it (manuals, diagrams and PCB-files)
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