Radio broadcast .. (1922-30)

Radio-Frequency Amplification from the Ground Up R.F.T FIG. 3 A vario-coupler and twin variometer regenerator and one stage radio-frequency amplifier may be made from Fig. i as shown here the secondary terminals and the wiring to their right and to the left of X4 and X5 should be made in a permanent manner with "bus" wire if it is available. Where a standard regenerative circuit is employed, the connections are made as in Fig. 2. In order to employ a variometer and twin variocoupler regenerator, the circuit in Fig. 3 is used. Where a Tunit unit is used to convert a standard long-wave receiver into a short-wave outfit, the Tunit is merely plugged in, in place of the three multi-layer coils. For those who would employ a loop antenna there are two methods available — the non regenerative and the regenerative. The difference is found in that portion of the circuit between X4 and X5. Where regeneration is not desired, it is but necessary to connect a short piece of wire between these two points. But regeneration is usually desirable, and is obtained by connecting a variometer between X4 and X5. The loop itself should be provided with two flexible leads, twisted together and attached to a plug which may be used in place of the secondary coil of the three-coil regenerator. When a loop antenna is employed, the regular antenna should be removed from the set and the primary coil should also be taken out. MAM i/VWVV FIG. 4 For loop reception no primary is used. The loop is plugged in across the terminals X2 and X3. If direct connection is made between X4 and X6, as shown by the dotted line, the receiver will be non-regenerative. The usual variometer method of producing regeneration is indicated at the right by dotted lines