The T03DSP High Performance Transceiver with DSP IF processing

Designed by Oleg Skydan UR3IQO

The Power Amplifier Board

The three stage power amplifier uses a common techniques to archive the necessary parameters.

The first two stages operate in class A and the third - AB. I used Russian transistors designed specially for the linear amplifiers.

The design goal was to get 10W of an exceptionally clean signal (for using with external linear) and 20-25W with usual parameters for 12V amplifiers. Here are the results:

Output power IMD3 below PEP IMD5 below PEP

10W 42 dB 58 dB

20W 29 dB 52 dB

I have optimized final stage quiscent current for the minimal fifthorder intermodulation distortion (IMD5).

The spectral display of the T03DSP transmitter during twotone intermodulation distortion (IMD) testing on HF. The worst-case third-order product is approximately 42 dB below PEP output, and the worst-case fifthorder is approximately 58 dB down. The transmitter was being operated at 10 W output at 3.600 MHz.

The spectral display of the T03DSP transmitter during twotone intermodulation distortion (IMD) testing on HF. The worst-case third-order product is approximately 29 dB below PEP output, and the worst-case fifthorder is approximately 52 dB down. The transmitter was being operated at 20 W output at 3.600 MHz.

The schematics of the power amplifier board is here.

All materials provided here are copyright by Oleg Skydan. In all cases, materials are provided for the purpose of self education and training in Amateur Radio. No use may be make for commercial purposes without permission of the author. Please send any comments and questions to Oleg Skydan UR3IQO.

Made in Ukraine

Output power	IMD3 below PEP	IMD5 below PEP
10W	42 dB	58 dB
20W	29 dB	52 dB