Circuit Diagram　 　Bill of Materials

This unit amplifies the power required to drive the final linear amplifier from each exciter transmitter. The basic design of this unit was designed by an amateur radio operator I know, and was then turned into a printed circuit board so that it could be controlled by a system. It was built by a few friends. I have permission to post it here. It is a source follower class A power amplifier using Mitsubishi FETs. I ran it on a +30V power supply and combined two units (PA-15) to obtain an output of 30W (PA-30) for an input of 150mW, with an IMD3 of -50dB or less. (Power gain is about 20dB) �@　Since this is a Class A amplifier, the bias current is large, so normally (in receiving mode), the bias current is set to 0, and the bias current is active only when transmitting (TXB = 'H'). �A　The temperature sensor is sandwiched between the solder side of the board and the FET. �B　The rotation speed of the heat dissipation fan is controlled by temperature feedback to maintain a constant temperature. �C　When installing the FET, the case must be the same as the drain, so it must be installed with an insulating sheet. Please refer to the circuit diagram for setting and adjustment methods.

Finished Product	Circuit Board Unit
MAIN

Measurement in one unit (Currently, the challenge is to reduce 5th/7th/9th order distortion.)

2TONE at 1W output, 3rd order IMD=-66dB	2TONE at 5W output, 3rd order IMD=-60dB
2TONE at 15W output, 3rd order IMD=-51dB	2TONE waveform at 25W output