WIDE-BAND OPEN-WIRE PROGRAM SYSTEM 367 



mately 50 cycles to 8,000 cycles, enabling the observer to cover the 

 entire program frequency range, thus permitting him to detect any 

 extraneous interference which may be introduced even though this 

 occurs at very low or very high frequencies. 



The third type of monitoring consists of two loudspeakers and 

 associated equalizing network with the loudspeakers mounted in a 

 large bafifle board. This arrangement affords a fairly uniform response 

 from about 40 cycles to above 8,000 cycles. The particular type of 

 monitoring which might be provided at the various stations would 

 be governed by the service requirements involved. 



To observe the volume on the program circuit, volume indicators 

 are used. A new type of volume indicator was made available along 

 with the new program system. This new device utilizes a full-wave 

 copper oxide rectifier, has a much greater sensitivity range than that 

 of the devices formerly used and possesses materially improved indicat- 

 ing characteristics. The volume indicator is connected across the 

 monitoring terminals of the line amplifier, in which position it is 

 bridged across a practically non-reactive 600-ohm impedance. Lo- 

 cated thus it is also independent of line impedance affording more 

 accurate results and obviating the necessity of correcting volume 

 readings on account of line impedances. Also at this location it 

 introduces no loss or phase distortion to the through program circuit. 



The above constitutes a description of the major items employed 

 in this program system. There are a number of other units, such as 

 attenuators, repeating coils, etc., which will not be described in detail 

 here but will be referred to as the need arises. 



Typical Station Layouts 



Due to the various requirements for different types of service and 

 due in part to the different type of facilities, the general apparatus 

 layouts and arrangements at different repeater stations are not always 

 the same. Several of the more important general or typical layouts 

 will be briefly discussed, however. 



On Fig. 15 is shown a layout of a typical intermediate station where 

 bridging is not required and where the gauge of the wires in the two 

 directions is the same. As may be noted from this figure, switching 

 facilities are provided so that the apparatus may be connected into 

 the circuit so as to properly take care of either the east-west or west- 

 east transmission. For this type of layout most of the apparatus is 

 common to both directions of transmission. The fixed artificial lines 

 or pads indicated by Note 1 on Fig. 15 are for the purpose of building 

 out whichever line has the lower 1,000-cycle attenuation so that this 



