Zenith-Radio-Corp-H401 电路原理图.pdf

《Zenith-Radio-Corp-H401 电路原理图.pdf》由会员分享，可在线阅读，更多相关《Zenith-Radio-Corp-H401 电路原理图.pdf（5页珍藏版）》请在收音机爱好者资料库上搜索。

1、收音机爱 好者资料库 RadioFans.CN MANUAL OF 19S2 MOST-OFTEN-NEEDED RADIO DIAGRAMS Zenith Model H401, Chassis 4H40, continued from previous page, S5 DET. AMP The 4H40 chassis is an AC, DC or battery operated super heterodyne. The chassis is isolated fron:i the DC circuit, _ and all measurements must be made fr

2、om a common nega- tive point. The most convenient place to reach this negative point is the negative side or container of the electrolytic. When the change-over Switch SI is in AC position, the DC resistance from chassis to any circuit must be almost in- 7 finite. If any circuit becomes grounded a h

3、um will result. . _ Microphonic tubes will cause audio howl. Check the 1R5 and 1S5. If the R.F. becomes weak or dead, check the DC resistance of the wavemagnet. This DC resistance shoild be approximately .9 ohm. If it is open check the wavemagnet. IF Alignment: Remove the chassis from the cabinet an

4、d ar range the units so that the wavemagnet can be connected.- All the connections and adjustments can be made from the . top of the chassis. Connect a signal generator, through a 2*0210% .1 mfd. dummy antenna, to the converter grid and B-(com- _ , mon return). Connect an output meter across the voi

5、ce coil of the speaker (two lugs provided). Set the signal generator to 455 Kc. and adjust L3, L4, L5 and L6 for the meucimum in- R dication on the output meter. Always keep the signal output from the generator just high enough to get an indication, otherwise excessive loading may result. I ALTERNAT

6、E AUDIO CIRCUIT USED ON LATER RELEASES. 3V4 PWR. AMP. .004 100 ,00011 RF Alignment: Connect a two turn loop across the leads of the signal generator, loosely couple this loop to the wave magnet. Set the signal generator and the dial pointer of the receiver to 1600 Kc. and adjustC3 oscillator trimmer

7、 to resonance. Set the signal generator and dial pointer to 1400 and adjust CZ antenna trimmer to resonance. These trimmers are on the top of gang condenser. Check operation and re install set in cabinet. Tune in a weak station near 1400 Kc. or use background noise and readjust antenna trimmer for m

8、aximum sensitivity. BATTERY CABLE - & PLUG WHEN SP-2 IS USED C-18 AND C-19 MUST ALSO BE USEa The I.F. transformers incorporated in this receiver are of the new permeability tuned type. The advantage of an I.F. transformer of this type is its extreme stability under vari ous humidity and temperature

9、conditions. The upper coil is the secondary and the lower the primary. When adjusting these I.F. transformers the tuning wrench 68-19 can be in serted into the top slug, rotated until maximum output is obtained and then dropped down to the lower slug and the same operation repeated. The tuning wrenc

10、h is so designed that turning one slug does not affect the adjustment of the other. TUBE AND TRIMMER LOCATION 1ST I.F. TRANS- INSERT A.C PLUG- HERE FOR BATTERY OPERATION L5PRI. BOTTOM- 2 ND. I.F. TRANS.- ALTERNATE USED ON LATER RELEASES I. F. TRANSFORMER Z2 ANT. trimmer :3 OSC. TRIMMER -VOLUME CONTR

11、OL & ON-OFF SWITCH -TUNING -68-19 alignment WftCNCH OPERA- CONNECT DUMMY INPUT SIG. TION OSCILLATOR TO ANTENNA FREQUENCY p-ND TRIMMERS PURPOSE C onverter Grid Two turns loosely coupled to Wavemagnet Two turns loosely coupled to Wavemagnet L3, 4, 455 Kc. BC 600 Kc. 5 6 I.F. Alignment 1400 Kc. BC 1400 Kc. Trim. Wavemagnet C2 N33119 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN