Philco-Radio-and-Television-Corp-RT-400 电路原理图.pdf

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1、Ill 收音机爱 好者资料库 RadioFans.CN VOLUME R-20, MOST-OFTEN-NEEDED 1960 RADIO SERVICING INFORMATION PHILCO Stereo AM/FM Tuner, Model RT-400, Continued ; . * 6 % |S. j 5 K 3 i C c .S U ?8 o.-S - O . 2 2 3 ;tTU PS -g c o is u c r4 . 1 rt 2 H O 04 J B$ IN s L C/) . o r j: n *0 0$ .5 S. o rt *- O S .2 ” s a 3 O

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3、12 Top ViewShowing Alignment Points, Tube Locations, Tie Lugs and Components 收音机爱 好者资料库 RadioFans.CN VOLUME R-20, MOST-OFTEN-NEEDED 1960 RADIO SERVICING INFORMATION PHILCO Stereo AM/FM Tuner, Model RT-400, Continued SPECIFICATIONS This tuner is equipped with a front panel and mounting board and is i

4、ntended for quick installation in the space provided in the H line Philco Hi-Fidelity Phonographs. CIRCUITNine-tube superheterodyne plus rectifier Function switch allows reception on AM only, FM only, or AM/FM stereo. FREQUENCY RANGESAM broadcast 540 KC to 1620 KC FM broadcast 88 MC to 108 MC TUNING

5、 DRIVE RATIO10:1 on both AM and FM OPERATING VOLTAGE105 to 120 volts, 60 cycle AC only POWER CONSUMPTION45 watts INTERMEDIATE FREQUENCIESAM455 KC FM10.7 MC AM ALIGNMENT PROCEDURE The AM alignment should be completed before the FM alignment is performed. Before beginning the alignment, allow the rece

6、iver and test equipment to warm up for fifteen minutes. Dtal PointerWith the gang fully closed, adjust the pointer to coincide with the first small index mark to the left of the 54” (540 kc) on the scale. Tuner ControlsSet the function switch to the AM position and the AM tuning control as indicated

7、. Output IndicatorConnect a scope to output jack, J2. Signal GeneratorUse an AM r-f signal generator with 30% modulation 1 Connect generator, through a .05 pfd condenser, to the signal grid, pin 7 of the AM converter, S7 (6BE6). Connect the ground lead to chassis. 2. Set generator to 455 kc Fully op

8、en tuning gang. Adjust in order given, top of T8 bottom of T7, bottom of T8, and top of T7 for maximum output Repeat until no further gain is indicated 3. Connect generator to radiating loop. Set generator to 1600 kc. Set receiver to 1600 kc as indicated by pointer Adjust VC7A (osc. trim mer) for ma

9、ximum output 4. Set generator to 1400 kc. Tune receiver to signal and adjust VC5A (antenna trimmer) and VC6A (r-f trimmer) for maximum output. 5. Set generator to 580 kc and tune receiver to signal; adjust core of r-f transformer (T5) for maximum output. 6. Repeat steps 4 and 5 until no further gain

10、 is indicated. FM ALIGNMENT PROCEDURE The AM alignment should be completed before the FM alignment is performed 1. With the gang fully closed, adjust the pointer to coincide with the first small index mark to the left of the 88 (88mc) on the scale 2. Set the function switch to the FM position and th

11、e FM tuning con trol as indicated. 3- Connect an oscilloscope, through a 100,000 ohm isolating resistor, to junction of R8 and C20. Connect the oscilloscope ground lead to the chassis. 4. Connect the signal generator to the cathode of the FM, RF ampli fier, pin 8 of Si. Connect the ground lead to th

12、e chassis 5. Inject a 10.7 MC marker signal and a 10.7 MC sweep signal, ap proximately 150 KC total deviation (do not over sweep) Adjust cores in top and bottom of T3, T2 and Tl for maximum amplitude, symmetrical curve with the 10.7 MC marker at the cop of the curve Adjust input signal to maintain o

13、utput, as indicated on scope, below 2 volts peak during alignment. Repeat this step until no further gam is obtained. 6. Change scope connections to the output connector J2. Inject a 10,7 MC, 30% AM modulated signal to the grid of the 6AU6, pin 1 of S4, Adjust top of T4 for minimum indication betwee

14、n peaks. Inject 10.7 MC sweep signal, approximately 150 KC total deviation, to pin 1 of S4 and adjust bottom of T4 for maximum-amplitude, sym metrical output Adjust input signal to maintain output, as indicated on scope, below 5 volts peak during alignment. (See NOTE below ) 7. Open tuning capacitor

15、 Insert a 6-mil, non metallic shim between stator and rotor of the FM gang and then close the capacitor against tbe shim Inject 108 5 MC sweep signal (approx. 150 KC total devia tion), through an antenna matching network, to the receiver antenna terminals Adjust VC3 for maximum output. 8- Close (mes

16、h) the tuning capacitor Inject 87.75 MC sweep signal (approx, 150 KC total deviation) through an antenna matching net work, to the receiver antenna terminals, and adjust X3 for maximum output (see NOTE below). 9- Set pointer to 91 MC and inject a 91 MC sweep signal. Adjust X2 for maximum output. (Se

17、e NOTE below ) 10 VC4 is the oscillator bridge capacitor used to minimize oscillator radiation. This is a factory adjustment and should not require fur ther adjustment in the field NOTE: The signal input must be as low as possible In order to obtain a sharp indication, in some cases it may be neces sary to set the signal generator to the first sub-harmonic. 3 Vz TURNS CORf A CORO C 3 V2 TURNS Drive Cord Installation Details 113 收音机爱 好者资料库 RadioFans.CN