RF Modem with 250mW Power

The project shows a homemade, cloth iron soldered, range extender for RF transceiver chip CC1101 that is included onboard.

In the design, a MAX2233 RF amplifier was used which can deliver up to +24dBm or 250mW of RF amplification with +10dBm of input. The chip has a data transfer speed from 1.2kbps to 500kbps with a frequency of 779-928MHz. the modulation schemes include 2 FSK, GFSK, MSK, OOK, and ASK. The chip is ready for frequency hopping as well as package protocol, CRC check, and automatic address match.

The original power of 10mW is boosted to almost 250mW or 1/4W after adding RF amplifier. When the MAX2233 RF amplifier is powered by 3.6V, it can deliver up to 250mW. The current output power is less than 250mW since the voltage used is 3.3V LDO on the board. everything is still compatible with 5V TTL levels which are done with the aid of MAX3377 or MAX3378 even though all electronics on this ,odem work on 3.3V.

During the testing, two modems and two antennas were used. A monopole antenna with 900MHz at the transmitting side and directional Yagi with 900MHz at the receiving end.

Rest of the project