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9. Maintenance
WARNING! The receiver will, under normal conditions, remain in align-
ment over an extremely long period time, consequently ALL POSSIBIL-
ITY OF OTHER CAUSES OF LOW SENSITIVITY SHOULD BE ELIM-
INATED BEFORE RE-ALIGNMENT IS CONSIRED, and should then
only be undertaken by order of the Engineer responsible for the mainte-
nance of the equipment.
Should it become necessary to re-align any part of the receiver only a
very small angular adjustment of the trimmers should be necessary unless
units have been changed.
TEST EQUIPMENT REQUIRED FOR MAINTENANCE
1. The following items of test gear are required to carry out the maintenance described
in this section of the manual:-
(1) Valve voltmeter reading up to 10V at frequecies up to 70 Mc/s.
(2) Signal generator capable of operating on fundamental frequencies up to 40 Mc/s.
(3) Digital frequency meter measuring frequencies at least up to 2 Mc/s.
(4) Multimeter measuring A.C. and D.C. quantities uo to 500V with recistance of
20,000 ohms per volt.
(5) Heterodyne wavemeter measuring 40 – 70 Mc/s.
(6) Telephone headset (low impedance).
(7) Output power meter.
(8) Noise generator TF1106 Marconi. (or similar)
(9) Miscellaneous: viz. 0
.
1
µ
F capacitor, 4.7 kilohms resistor and 12pF trimmer ca-
pacitor.
NOTE:
Major uses of the RA.117 receiver are advised to obtain factory type test jigs for
alignment of the various units. details of these jigs and specially designed test gear
will be supplied on request. A supplement to “ALIGNMENT PROCEDURES”
describing the employment of this gear can be made available to such users./par
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