It's not that I would absolutely need one! This new amplifer must have at least one technical advantage over plain simple common traditional amplifiers: Either it must be ultra low cost along with respectable performance, or it might be extremely small and lightweight, extremely efficient, or anything else like that. It should be an interesting amplifier, not just a brute force tool to get high RF power. I warmly welcome contributions! My e-mail address is.
2016 Extra Class study guide – E7B – Amplifiers
Extra Class question of the day: Amplifiers - KB6NU's Ham Radio Blog
Often these linear amplifiers are needed when stations want to increase the power being transmitted to the full legal limit as many transceivers, HF, VHF and UHF do not provide this power output level. Linear RF amplifiers are required where signals that have an amplitude component are used. These amplitude components carry information and for this to be accurately preserved, the signal must be amplified in a linear fashion. Signals including amplitude modulation, single sideband, and quadrature amplitude modulation are the main ones and for amateur radio, linear amplifiers are required for single sideband. If the RF amplifier is not linear, then the signal will be distorted and this will result in intermodulation products spreading out either side of the signal to create what is termed splatter. To ensure that no undue levels of splatter are generated so that the minimum amount of interference is caused to other users, it is essential that all additional amplifiers remain linear. Signals that do not carry amplitude variations such as FM signals can use non-linear amplifiers like class C amplifiers which are much more efficient and do not need the same level of heat sink capability etc.
Power amplifier classes
Schematic of most of amplifier:. Schematic of final stage of amplifier:. Schematic of control circuit:. Place the unit on the table in front of you with the fan on the right hand side and the removable cover facing up.
A class C amplifier is one in which high plate-circuit efficiency and high power output are the primary considerations. In an ideal case, the alternating component of plate current is directly proportional to plate voltage, so that within wide limits the power output varies as the square of plate voltage. The tube is operated with a negative grid bias considerably higher than the value necessary to cause plate-current cut-off. An r-f grid voltage of sufficient amplitude is applied so that large amplitudes of plate current flow during a small fraction of the least-negative half-cycle of the exciting voltage. The grid is usually swung sufficiently positive to cause plate-current saturation.