Modular adjusting device, in particular for RF devices, having the following features: - comprising at least one rotatable drive train having at least one transmission (11; 11', 11") and having at least one rotatable shaft or one rotatable shaft portion (13.1, 13.2, 13.3, 13.4), - the at least one transmission (11; 11', 11") comprises at least two rotatable transmission members, specifically at least a first and a second transmission member (29, 31), which are in an operative connection with one another or mesh with one another, - the at least two rotatable transmission members (17; 29, 31) are held in or on a transmission base module, characterised by the following further features: the at least one transmission base module further comprises an associated snap-in and/or latch device for the second transmission member, - the first transmission member is held and secured by the associated snap-in and/or latch device so that it snaps in and is rotatable at the same time, and - the snap-in and/or latch device is formed in such a way that the first transmission member is held so as to be stop-delimited in the axial direction, - the at least one transmission base module further comprises an associated snap-in and/or latch device for the second transmission member, - the at least one second transmission member is held and secured by the associated snap-in and/or latch device so that it snaps in and is rotatable at the same time, - the snap-in and/or latch device for holding and securing the at least one second transmission member is formed in such a way that the at least one second transmission member is held so as to be stop-delimited in the axial direction, and - the first and the second rotatable transmission member (29, 31) each comprise a plug-in coupling region, in which in each case one of the shafts or one of the shaft portions (13.1, 13.2, 13.3, 13.4) is connected in a rotationally fixed manner to the first or to the second rotatable gear element (29, 31) by means of a plug-in connection. - comprising at least one rotatable drive train having at least one transmission (11; 11', 11") and having at least one rotatable shaft or one rotatable shaft portion (13.1, 13.2, 13.3, 13.4), - the at least one transmission (11; 11', 11") comprises at least two rotatable transmission members, specifically at least a first and a second transmission member (29, 31), which are in an operative connection with one another or mesh with one another, - the at least two rotatable transmission members (17; 29, 31) are held in or on a transmission base module, - the first transmission member is held and secured by the associated snap-in and/or latch device so that it snaps in and is rotatable at the same time, and - the snap-in and/or latch device is formed in such a way that the first transmission member is held so as to be stop-delimited in the axial direction, - the at least one transmission base module further comprises an associated snap-in and/or latch device for the second transmission member, - the at least one second transmission member is held and secured by the associated snap-in and/or latch device so that it snaps in and is rotatable at the same time, - the snap-in and/or latch device for holding and securing the at least one second transmission member is formed in such a way that the at least one second transmission member is held so as to be stop-delimited in the axial direction, and - the first and the second rotatable transmission member (29, 31) each comprise a plug-in coupling region, in which in each case one of the shafts or one of the shaft portions (13.1, 13.2, 13.3, 13.4) is connected in a rotationally fixed manner to the first or to the second rotatable gear element (29, 31) by means of a plug-in connection.