For me it was always very interesting to learn what minimum equipment is needed to make EME QSOs, especially on 23cm. I extended a W2IMU feed made of 6mm mesh by adding a large cone, achieving a horn antenna with 80cm mouth diameter. Estimated gain is 19dBi, maybe slightly less.

A spare 80W SSPA was used for the transmit side. Together with the horn I got 49dBm+19dB=68dBm EIRP.