Radio Broadcast (May 1928-Apr 1929)

88 RADIO BROADCAST JUNE, 1928 B+ 45 Ant. on Set of Receiver O B + 90 CIRCUIT OF THE BOOSTER UNIT The antenna connection indicated will work with all Browning-Drake type receivers" with others, it is best to connect the antenna lead to the set directly to the stator plates of the first tuning condenser not only on Browning-Drake sets, but on any existing receiver, simply by making a connection to the stator plates of the first tuning condenser. [The lead from the "booster" may be connected to the antenna posts of some receivers, but not all, and it is best to follow the suggestion here which is certain to work. — Editor.] By using this one-stage device, the writer has received signals that were inaudible before. The assembly of the one stage screen-grid booster is quite simple. The Browning-Drake Corporation furnishes a kit consisting of the coil, condenser and dial, together with a set of aluminum shields, a radio-frequency choke, a four-wire cable, 10-ohm resistances and the mounting hardware, and all that is necessary for the constructor to purchase is a tube socket, and the three following condensers; a 5 mfd., a 0.0001 mfd. and a 0.00025 mfd. The picture wiring diagram and the schematic wiring diagram are presented on this page. It should be noted that the stator plates of the tuning condenser go to the top of the screen-grid tube. The two 10-ohm resistances, put in as indicated, cut down the six volts from the storage battery to 3.3 volts which is the correct voltage for the screen-grid. It is noted that the one-stage booster is run from a battery as the writer does not believe it feasible to light the filament of the cx-322 from raw a.c. In using the one-stage booster on any Browning-Drake assembly, all that is necessary to do is to disconnect the antenna from the set, connect it to the antenna post of the booster, which is shown on the left, and to connect the wire lead, which is on the right of the booster to the antenna post on the Browning-Drake receiver. The ground is left in its position on the set proper. From the wiring diagrams, it may be noted that a filament switch is inserted in the plus-A battery lead to control the filament of the cx-322 tube. This makes the separate amplifier unit independent of the receiving set proper and permits it to be used on any radio set. When using the booster on Browning-Drake receivers, particular care should be taken that the set is well neutralized before adding the booster. Volume may be controlled as before on the receiving set. HOW TO CONNECT THE BOOSTER \ A/HEN using this one-stage booster with " * other receivers, the wire on the right of the shield casing, is connected to the stator plates on the first tuning condenser. The other connections are unchanged, except that the antenna lead is connected to the proper post on the booster. The operation of the booster is very simple indeed as all that is necessary to do is to tune-in the receiver by means of the regular control and then tune the booster. Tuning on the booster unit is not extremely critical though it increases the selectivity of the set in a marked degree. The antenna used on the receiver when this booster is employed should be very short, in fact, not more than 25 to 40 feet, and as nearly vertical as possible. The vertical antenna will pick up relatively a stronger signal. LIST OF PARTS 1 Browning-Drake Booster 322 Kit assembly. (Includes shields, the coil and tuning condenser with dial, two 10-ohm resistances, a four-wire cable, shield wire, and r.f. choke). 1 ux tube socket. 1 0.000 1 -mfd. mica Condenser. 1 f-mfd. mica Condenser. 1 0.0002 5-mfd. Condenser. . 00025 mfd To Antenna on Set PICTURE DIAGRAM How to connect the various parts employed and the recommended layout