Q multipliers are circuits that increase the selectivity of a telecommunication receiver, such as those used by hams. The circuit we use uses only one tube (half a double triode) and was obtained from a 1965 publication. The circuit uses an IF transformer that must be set to the same IF frequency as the receiver with which it will operate. The power supply can be obtained from the same source as the receiver, without problems, since the consumption is very low. In this circuit, the CH1A switch to which the signal goes, is connected to the board of the first IF amplifier tube of the receiver.
