THE N-1 CARRIER SYSTEM 



23 



except for provision of an ambient temperature compensating circuit. This 

 circuit consists of a heater electrically insulated from the pellet and con- 

 trolled by a disc thermistor at the repeater temperature. As the repeater 

 temperatures decreases, the disc thermistor increases its resistance, allowing 

 more current to flow into the heater winding. The thermistor pellet is 



70 



^i< 60 



LUZ 

 CQlU 



a2 



ULl< 



Z 



§5 



i% 



(a) 



(b) 



8 10 12 14 16 18 20 22 



OUTPUT OF EACH FUNDAMENTAL IN DBM 



24 26 28 



(C) 



<(0 

 O-l 



UJ 



z5 



UJUJ 



Is 



I 

 o 



12 



20 21 

 IN DBM 



22 23 24 25 



Fig. 



14 15 16 17 18 19 

 SINGLE FREQUENCY OUTPUT 



10(a) — Low-high repeater modulation. 



(b) — High-low repeater modulation. 



(c) — Gain-load characteristics of high-low and low-high repeaters 



maintained at a nominal or thermostated temperature which, in general, 

 is from about 135° to 185°F. This allows operation of the regulator with 

 repeater temperatures from about — 20°F to 130°F with little change in 

 its control range. Beyond these temperatures the performance deteriorates 

 slowly. 



The low level operation of the modulator and repeater amplifier combined 

 with the high level of carrier in the modulator and large amplifier feedback, 

 result in low interchannel modulation. In Fig. 10, (a) and (b), one- and two- 



