Automatic-tuning communication transmitter

An illustrated description, without circuit diagrams, is given of versatile equipment which can be automatically tuned and matched to specified aerials at any frequency from 300kc/s to 26Mc/s. Any one of 10 preset frequencies can be selected, or any frequency in the operating range set up by manipulation of a group of knobs with direct frequency indication, the actual tuning being effected automatically for most frequencies in about 30sec, the maximum time being 90sec. The power output of the transmitter is limited to 100W from 300kc/s to 2Mc/s. From 2Mc/s to 26Mc/s, the output may be either 100W or 500W. Keying speeds up to 600words/min are possible and either polar or neutral keying signals are acceptable. Radiophone operation, using a standard carbon or dynamic microphone, is practicable. Provision is made for facsimile operation with a 600Omega input circuit, using frequency-shift modulation. Frequency-shift keying, with or without ph.m., can also applied. The three standard equipments are built up from four basic groups: (a) the transmitter group, subdivided into the 100W equipment and additional equipment bringing the output to 500W; (b) the aerial-control group, mounted at any convenient place but preferably near the transmitter bay; (c) the aerial-tuning unit and capacitor assembly, always mounted at the base of the aerial to be used; (d) the dial-type channel selector for the preset channels, with indicator showing the channel in use. The AN/URT-2 equipment comprises the 100W transmitter with groups (b),(c)and (d). The AN/URT-3 equipment includes also the units bringing the output power to 500W. The AN/URT-4 equipment comprises two AN/URT-2 sets and a booster section, thus providing two complete systems capable of operation on different channels at the 100W level. Some details are given of the main features of the various units and of their operation.