General-Electric-Co-221 电路原理图.pdf

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1、收音机爱 好者资料库 RadioFans.CN 9. MANUAL OF 1947 MOST-OFTEN-NEEDED RADIO DIAGRAMS GENERAL ELECTRIC RADIO Disconnect signal generator from 12SG7 and connect (through .05 mf. capacitor) to pin eight of the 12SA7 converter. 10. Keeping output below volts as before, peak the first i-f trimmers, CIO and Cll, fo

2、r maximum output. 11. Check second and first i-f trimmer adjustments. TWO-BAND A-C-O-C SUPERHETERODYNE SERVICE DATA for MODELS 219, 220, 221 ALIGNMENT Needed. Signal Generator, modulated 30% with 400 cycles. One60 mmf. capacitor One.05 mf. capacitor One400-ohm resistor Oneoutput meter Oneinsulated s

3、crew driver. Bnmikmst M-f AUpmmuK When making the following alignment, the Beam-a-Scope (loop antenna) must be mounted to the chassis, and the chassis must be installed in the cabinet. All trimmer adjust ing screws are available through the hole in the loop antenna frame. 1. Connect the output of th

4、e signal generator through a 60 mmf. capacitor, to the radio antenna post. 2. Set the signal generator and dial pointer to 1500 kc. 3. Adjust C14, C8, and C2 for maximum output. If two peaks are obtained when adjusting C14, the correct point is the one with the trimmer plates the furthest apart. 09m

5、ral, For a complete alignment, the i-f should be aligned before the r-f. The i-f sections may be aligned with the chassis removed from the cabinet, but for the final r-f alignment the chassis should be in place, in the cabinet. Fig. 3 identifies and locates all trimmers. Be sure the radio has been “

6、on” for at least 10 minutes before making any alignment adjustments. In order to be sure of frequency stability in the signal generator, follow the manufacturers recommended procedure for use. When making connections to the signal generator, avoid any ground connections to the radio unless an isolat

7、ion transformer is used in the power line. Sktrtwmv* K-f iUlgsaiMt. 1. Set Band Change switch to SW position. 2. Set dial pointer and signal generator to 9.5 me. 3. Remove chassis carefully, so as not to disturb the setting of the dial pointer. 4. Connect the output of the signal generator through a

8、 .05 mf. capacitor to pin eight of the 12SA7 converter tube. Adjust C13 (under the chassis) for maximum output. Two points of maximum output may be obtained. The correct point is the one with the trimmer plates closest together. Remove the signal generator connection, and connect its output through

9、a 400-ohm resistor to the radio antenna post. Peak C7 for maximum output while rocking-in the main tuning condenser. Replace the chassis in the cabinet, and check the setting of C7. 5. 6. 7. I-f Aligmmnt. 1. Remove chassis from cabinet. 2. Connect output meter across the speaker voice coil. 3. Set v

10、olume control for maximum. 4. Connect output terminal of signal generator through a .05 mf. capacitor to pin 4 of the 12SG7 (i-f amplifier) tube. 5. Set signal generator frequency to 455 kc. 6. Set dial pointer on radio to approximately 1500 kc. 7. Peak second i-f trimmers, C16 and C17, for maximum

11、output. It is important to keep the output reading under 1 volts by reducing the input or gain control so as to avoid spurious results due to a.v.c. action. STAGE GAINS AND VOLTAGE CHECKS The following information will be useful to servicemen equipped with vacuum tube voltmeters or similar voltage m

12、easuring instruments. The stage gain values listed may have a tolerance of 20%. ItSfs Gatos. (1) Antenna terminal* to pin 4 of 12SK7. 1000 kc (2) Pin 4 of 12SK7t to pin 8 of 12SA7. 10 1000 kc 8. q,. 455 kc 455 kc (3) Pin 8 of 12SA7t to pin 4 of 12SG7. 35 (4) Pin 4 of 12SG7t to pins 4 or 5 of 12SQ7. . . .100 Connect to signal generator output through a 60 mmf. capacitor. t Connect to signal generator output through a .05 mf. capacitor. - CI3 S.W.TRIMMER p underside of chassis) C7 mm S.W. BC BC R-F R-F OSC. ANT. TRIMMER- CON LCOP) C2 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN