Noblitt-Sparks-Industries-Inc-RE-274 电路原理图.pdf

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1、MANUAL OF 19S0 MOST-OFTEN-NEEDED RADIO DIAGRAMS ARVIN RADIOS - MODELS 341T CHASSIS RE-274 4 TUBE AC-DC MANUFACTURED BY NOBLITT-SPARKS INDUSTRIES, Inc., COLUMBUS, IND. ALIGNMENT PROCEDURE PRELIMINARY: Output meter connection . Output meter reading to indicate 200 milliwatts (standard output) Dummy an

2、tenna to be in series with signal generator output . Connection of generator ground lead . Generator modulation . Position of Volume Control . Position of pointer with variable fully closed . Across loudspeaker voice coil 0.8 volts See chart below . Floating ground . 30% 400 cycles . Fully clockwise

3、 . 54 on dial Position Generator Dummy Generator Trimmers Trimmer Approximate of Variable Frequency Antenna Output Connection Adjuster Function Sensitivity Open 455 Kc .05 uf 12SA7 Grid (Stator of C-l) 2 trimmers on top of T-3 IF 3000 uv 1400 Kc 1400 Kc .00005 uf Antenna lug with Ant. Removed C-2 Os

4、cillator 360 uv Since the antenna section of the variable has no trimmer, the rotor of the variable should be rocked back and forth on both sides of 1400 Kc while adjusting the oscillator trimmer for maximum output. This is to obtain the combination of rotor and trimmer setting to give perfect track

5、ing of the two sections of the variable condenser and consequently give maximum output. Check sensitivity at 600 Kc. If weak, adjust antenna section plates for maximum output at 600 Kc. Tracking of the condenser at points other than 1400 Kc is accomplished by bending the outside plates on the variab

6、le condenser rotor, which are cut for this purpose. When bending plates to track the condenser at any given frequency, keep in mind the fact that this will affect the tracking at all frequencies below the point where the plates are bent. A tunihg wand is very helpful in checking the tracking of this

7、 condenser, to indicate whether more or less capacity is needed. The alignment procedure should be repeated stage by stage in the original order for greatest accuracy. Always keep the output from the test oscillator at its lowest possible value to make the AVC action of the receiver ineffective. 收音机爱 好者资料库 RadioFans.CN