A signal generator is one of the radio serviceman's basic test instruments. In the Simpson 340 Signal Generator we have provided at a moderate price an instrument of highest accuracy, greatest stability, minimum leakage and good wave form. It gives a test signal source that will maintain its accuracy under constant use. It enables you to "troubleshoot" fast and accurately every time. The big nine-inch meter type dial, with hair-line pointer, gives high readability. Smooth vernier control permits close settings. Your pride in your Model 340 will grow as you learn of its many hidden virtues—the unusual quality of materials from which it is made, the advanced electronic engineering it embodies. Take the shielding as an example. The coils, the attenuator and the signal selector are individually shielded. Oscillator and modulator assemblies are sealed in a rigidly welded, entirely enclosed chassis. An effective line filter is used. Even the line cord is shielded. The result is to cut leakage to a minimum. These are but a few of the refinements of Model 340. 1. The Model 340 Signal Generator is designed to give the service dealer a practical, easy to use, test signal source that will maintain its accuracy in every-day use. Its big 9-inch meter type dial with .its long scale makes accurate settings an easy matter. The entire instrument, with its beautifully finished panel, gives a professional appearance that is an asset to any shop. The instrument is supplied with a shielded output lead and operator's manual. The standard model is for use on 115 volt, 50 or 60 cycle current supply. 2. FREQUENCY BANDS AVAILABLE 75-200 kilocycles 200-600 kilocycles 600-1700 kilocycles 1.5-4.5 megacycles 4.5-12 megacycles 10-30 megacycles 40-120 megacycles 400 cycle 30% modulation of above radio frequency bands 400 cycle audio frequency signal 3. CIRCUIT The electron coupled circuit assures extreme stability. Three tubes are used in the circuit, one 6X5GT as a full wave rectifier, one 6I5GT as a 400 cycle audio oscillator and modulator and one 6K6GT as the electron coupled RF oscillator. 4. OUTPUT The signal is controlled through a step attenuator of the ladder type, each step being regulated by a smooth non-inductive control. The RF output can be varied from a few microvolts to approximately .15 volts while the 400 cycle audio signal can be varied from 0 to about 3.5 volts.