This can be done hy coupling a 915 kc signal through a 1 mf. capacitor to the control grid of the 1st detector. Short the stator of the oscillator section of the tuning c apacitor (Section 1-D) to ground. The output should go up. This indicates that the oscillator was functioning statisfactorily. Do lhis on all bands.
(12) R-F AMPLFIER AND HETERODYNE OSCILLATOR.— Having completed the test and alignment of the audio amplifier, i-f amplifier and heterodyne oscillator, test the r-f amplifier as follows:
Turn the band switch to band No. 1. Set the receiver and generator controls as described in Table G Alignment Chart, No. I band column, but use a .l mf. dummy antenna and make the antenna connection to the control g rid of the 1st detector tube.
Turn the tuning controI until the test signal is picked up and carefully tuned in. The receiver dial should indicate the same frequency as the signal generator. If there is more than .75 per cent variation, the oscillator must be realigned as described beIow
Proceed to check the r-f amplifier, stage-by-stage, working towards the antenna. Couple the signal generator through the .1 mf. dummy antenna to the control grids of the 2nd r-f tube and the 1st r-f tube. Then, using a dummy antenna of 100 mmf, couple the signal generator to the antenna binding post. At each stage, the receiver output should incrcase substantially indicating the stage gain. If there is no gain, the stage should be checked for defective components, shorts and grounds, using Tables C, D and E.
Do this on all bands.
(13) R-F AMPLIFIER AND HETERODYNE OSC:I.LATOR ALIGNMENT.—Instructions are given in Table G Alignment Chart for completely aligning the r-f amplifier and heterodyne oscillator circuits. Start with number 1 band column and continue with all columns to the right.
f. WEAK OR NO SlGNALS ON ANY ONE BAND, MOdULATED RECEPTION.—The condition of satisfactory reception on several bands and weak or no signals on one or more bands indicates the correct functioning of the i-f and a-f amplifiers, and requires checking only the r-f amplifier and heterodyne oscillator for the defective band or bands. The procedure outlined in paragraphs 34e(11) to 34e(13) should be followed for the defective band or bands.
8 WEAK OR NO SIGNALS ON ALL BANDS— C • W RECEPTION MODULATED RECEPTION NORMAL)—Weak or no signals on all bands for c-w reception with satisfactory modulated signal reception,