linrad support: RF amplifier and filter for 70 MHz
(Nov 2 2002)

The RF amplifier

The RF amplifier uses noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift between gate voltage and channel current.

The input IP3 of the RF amplifier is in the order of +37dBm which is high enough to make the 70 to 10.7 MHz converter dominated by IM3 from the mixer.


Fig.1. Circuit diagram for the 70 MHz RF amplifier and filter.


Fig.2. The second channel differs only in component numbering.