MAINTENANCE


WARNING! The receiver will, under normal conditions, remain
in alignment over an extremely long period time, consequently
ALL POSSIBILITY OF OTHER CAUSES OF LOW SENSITIVITY SHOULD BE
ELIMINATED BEFORE RE-ALIGNMENT IS CONSIRED, and should then
only be undertaken by order of the Engineer responsible for
the maintenance 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. 0.1µF capacitor, 4.7 kilohms resistor
and 12pF trimmer capacitor.


NOTE: Major uses of the RA.117 receiver are advised to obtain factorytype
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.


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