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counter to P2 (BFO output). Connect the digital multimeter between TP8,
and ground and set on the 10 Volt dc range.
NOTE
With the probe of the digital multimeter on TP8 a FAULT may be indicated on
the front panel.
continued with the FAULT indicator on. FAULT indication should extinguish
when the digital multimeter probe is removed.
(9)
The digital frequency counter should indicate 455,000 +1 Hz.
multimeter should indicate between 4.5 and 7 Volts dc. If correct digital
multimeter reading is not obtained, adjust coil L4 for correct indication on
digital frequency counter.
(10)
Select BFO variable on the Receiver and tune the BFO over its entire range
(-8 to +8 kHz) while observing the Receiver front panel BFO and digital
frequency
counter
track 455,000 Hz above the Receiver BFO indicated frequency.
observe
the digital multimeter indication while tuning the BFO. Digital multimeter
should not deviate more than +1.5 Volts from reading obtained in Step 9 at
BFO center.
(11)
Disconnect the digital frequency counter from P2 and reconnect P2 of cable
W6 to J5 on A4. Disconnect the digital multimeter from TP8.
(12)
Disconnect PI of cable W3 from J2 on A7. Connect the digital frequency
counter and oscilloscope to PI. Ensure that the frequency is 1 MHz +0.5 Hz,
and the output level is switching between approximately 0 and +5 Volts
(TTL).
(13)
Turn the Receiver off. Disconnect digital frequency counter and oscilloscope
from PI and reconnect PI of cable W3 to J2 on A7.
j.
Front Panel Interface, Circuit Card Assembly A9.
This circuit card does not contain any variable components, and therefore does not
require any alignment or adjustment procedures.
Racal RA6790/GM Alignment & Tuning Manual
This is normal and alignment procedures should be
indications.
Digital
frequency
Digital
counter
should
Also
Page 13 of 20
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