Radio Broadcast (May-Oct 1925)

J How to Build a Two-Stage Detector-Amplifier Unit 463 Radio Broadcast Photograph form to the selection of parts as closely as possible to the list as shown. The heart of the unit is the two audiofrequency transformers. They have been selected because of the large cores upon which are wound plenty of wire. These two features In laying out the panel, place it face down on a table with its length running right and left. Now divide the length into two sections evenly, both of five inches each. The dividing line is the working center line. Working up, three quarters of an inch from the bottom TWO STAGE RADIO FREQUENCY AMPLIFIER DETECTOR TWO STAGE AMPLIFIER FIG. 8 How the detector two-stage amplifier would be connected to the two-stage radio-frequency amplifier described in the May, 1925, Radio Broadcast. The cut above shows the two units connected alone prevent over-saturation and insure against overloading. Those used in this amplifier are of a low ratio and are capable of taking a very strong signal and amplifying it without changing its characteristics. The circuit employed is that of Fig. 2. The numbered symbols in Fig. 2 are those with variable controls that are mounted on the panel. They may be identified in the panel illustration Fig. 3. ASSEMBLY IS EASY USING THE NUMBERS >~pHE construction of the detector-amplifier * is almost entirely a matter of assembly, and wiring. We suggest proceeding as follows: — After the parts have been obtained, the panels are prepared by drilling all the holes and graining the surface by rubbing with fine emery paper. scribe a line (1) across the length of the panel. On it will be located the two jacks. Then one half inch above it scribe another line (2) all the way across. This is for the socket mounting holes. Another line (3) is scribed FIG. 9 Here is how the batteries, A, B, and C are connected to the binding posts on the sub-base