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Alignment Procedures
42
Table 1
R.F. RANGE
INDUCTOR
ALIGNMENT
TRIMMER
ALIGNMENT
FREQUENCY
FREQUENCY
2 - 4
L7
2 Mc/s
C234
4 Mc/s
4 - 8
L6
4 Mc/s
C235
8 Mc/s
8 - 16
L5
8 Mc/s
C236
16 Mc/s
16 - 30
L4
13 Mc/s
(C18 at C237 max.)
30 Mc/s
Table 2
R.F RANGE
L.F.
H.F.
1 - 2 Mc/s
7mV
7mV
2 - 4 Mc/s
10mV
10mV
4 - 8 Mc/s
12mV
16mV
8 - 16 Mc/s
22mV
26mV
16 - 30 Mc/s
22mV
30mV
Crystal Calibrator
46. Should no output be obtained from this unit when the SYSTEM switch is in the CAL
position and the KILOCYCLES scale set at a 100 kc/s check point, or if spurious
responses are obtained over the kilocycles range, proceed as follows:-
Set the KILOCYCLES scale to a 100 kc/s point and check the tuning of L70 by
carefully rotating the core a half-turn either side of the setting. If the signal does
not appear, restore the core to its original setting and repeat the check with L75.
If the signal is heard, the cores of L70 and L75 should be set to centre of the
range of adjustment over which a clean signal is produced.
47. Should a major fault be suspected, or if L70 or L75 have been inad- vertently mis-
aligned, it will be necessary to remove the unit and make up an extension cable so
that the unit may be operated outside the receiver. The crystal calibrator may be
aligned as follows:-
Remove V13 and connect the valve voltmeter probe to grid 3 (pin 7). Inject a
900 kc/s c.w. signal, from the signal generator, at the grid of V15 (pin 1) and
adjust L75 for maximum output. Disconnect the valve voltmeter and the signal
generator, replace V13 and remove V15. Connect the signal generator to grid 1
(pin 1) of V13 and the valve voltmeter to the grid 1 connection (pin 1) of V15. Set
the signal generator to 100 kc/s c.w. and adjust L70 for maximum indication on
the valve voltmeter. Disconnect the valve voltmeter and the generator. Fit V15.
Connect the coaxial connector to PL2 on the receiver.
48. The output should be approximately 0.2V measured between pin 6 of the octal plug
and earth.
40
Mc/s Filter
49. This filter is over-coupled and cannot be readily aligned without a 40 Mc/s sweep oscil-
lator. Re-adjustment therefore should not be attempted unless the specially designed
test equipment and factory-type alignment jigs are available.
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