Sears-Roebuck-and-Co-7116 电路原理图.pdf

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1、MANUAL OF 1947 MOST-OFTEN.NEEDED RADIO DIAGRAMS Sears, Roebuck & Co. Models 7115, 7116, 7117, 101*825 Preliminary APPROXIMATE F.M. I.F. ALIGNMEWT Indicating meter connection. Generator ground lead connection. Generator output lead connection. Generator modulation. Position of volume control. Positio

2、n of tone control. Position of pointer with tuner fully closed. DC voltmeter connected across R24 . .Chass is .See Chart Below .Off .Fully on . .Treble (fully clockwise ) .Last line below 88 Me. Wave Band Tr imme r Switch Position Generator Dummy Generator Adjustments Trimmer Position of Tuner Frequ

3、ency Antenna Connection (in order shown) Function 收音机爱 好者资料库 RadioFans.CN MANUAL OF 1947 MOST-OFTEN-NEEDED RADIO DIAGRAMS Sears, Roebuck & Co* Models 7115, 7116, 7117, 101.825 FINAL F.M. ALIongNT A If a 10.7 Uc. frequency modulated generator is available, connect to translator grid through e 270 to

4、500 dim resistor and proceed to Section C, Bt If no 10.7 Uc. frequency modulated generator is available, connect an R.F. - F.M. generator to the F.M. antenna terminals. C. Connect 5000 dims (if generator sweep frequency is 60 cycles) to ground in parallel with R24. For lower frequency sweep increese

5、 the 5000 ohm resistor proportionately. Connect the- Y-axis (vertical) amplifier of an oscilloscope across jR24 to ground. Iit a 10.000 to 100,000 ohm resistor in series with oscilloscope lead (at receiver end) to provide R.F. filterings. D. Connect the sweep output of the generator to the X-axis (h

6、orizontal) amplifier of the a. lloscope. E. Adjust modulation for a 300 Kc. deviation and touch up alignment Of C41 ,C40,C32,C29,C25 and C22 for a symmetrical pattern on ascilloscope. Use full gain of the oscilloscope Y-axis amplifii. and only as much output from the generator as is necessary. See F

7、IG. lA, (PACE 11) for approximate pattern. F. Remove the oscilloscope and the two resistors that were added in Section C above. (Restore receiver to normal operating condition). G. Connect the Y-axis (vertical) amplifier of the oscilloscope to the ungrounded side of C53 through 10,000 to 100,000 dun

8、s at receiver end of lead. H. Adjust C4S for maximum output, vertically. Adjust C48 and C49 until the center of the pattern becomes a straight line diagonally across the as cilloscope screen. Re-peak these three trimmers to obtain a symmetricel pattern of maximum vertical amplitude. See ascilloscope

9、 pattern, FIG. IB. (PACE 11). I. Remove the generator. Remove the oscilloscope and resistor from CS3, and replace across R24 as das cribed in Section C above. J. Connect an R.F. F.M. generator to the terminals marked F.M. antenna through two 120-ohm resistors, one in series with each terminal of the

10、 generator. Adjust the generator for 300 Kc. deviation. K. Tune the generator to 109 Me. Set pointer to 109 Me. Adjust C8 to obtain 3rd. I.F. oscilloscope pat tern. See FIG lA (PACE 11). (If two such points are found by tuning C8, use the higher frequency.) (Lowest capacity setting of C8). L. Tune the generator and receiver to 106 Nc. and peak C6 and C4 for maximum vertical amplitude on the oscilloscope. (See FIG. lA below). M. Remove the signal generator, oscilloscope and resistors, restoring the receiver to normal operating cond it ion. iB-o/sce/w/Viaroe 收音机爱 好者资料库 RadioFans.CN