Racal Instruments RA-117 User Manual page 29

8. Set BANDWIDTH control to 3 kc/s. Refit the 1.7 Mc/s crystal XL300. Connect the
output of the signal generator to socket SKT301 (pink) and tune the generator to a
frequency of 1.6 Mc/s. The sensitivity should be better than 75 V for 100 A.
9. In the event of the figure above not being realized the renewal of V25 will probably
effect on improvement.
10. Refit the valve V12 and set the KC/S scale to 500. Connect the output of the gen-
eratorto socket SKT11 and set generator to a frequency of 2.5 Mc/s approximately
and tune for maximum deflection on the meter. The sensitivity should be better than
250 V for 100 A.
11. Set the kc/s scale to 0 kc/s and 1000 kc/s and the signal generator to 3 and 2 Mc/s
respectively. The sensitivity should not vary from 250 V by more than 3dB.
12. The maximum difference between check point should not exceed 3dB. The renewal of
V11, or V9 will probably effect an improvement if this figure is not met, providing
that the conditions outlined in previous paragraphs have been achieved.
13. Refit the crystal XL1 and check the 1 Mc/s output (SKT2 on top of the main chassis)
with the valve voltmeter to ensure that there is at least 2V output.
Fault Diagnosis
V26 Fourth mixer
V14 First I.F. amplifier
V16 Second I.F. amplifier
V27 1.7 Mc/s oscillator/amplifier
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