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3.2.10
3.2.11
LOCK, when displayed, indicates that the manual tuning knob is disabled. When the words
FAST, SLOW and LOCK are not displayed, the Receiver is in the "fine" tuning mode. If
the word BFO is present on the display, the manual tuning knob may be used to vary the
BFO frequency but
will
not change the receiver frequency. The word REMOTE is displayed
under two conditions: (I) control of the Receiver is under a remote device' (provided the
Receiver is equipped with the optional A6Al circuit assembly) and (2) the Receiver is
executing a BITE test routine whether under LOCAL control or initiated remotely.
Right (Frequency Data) Liquid Crystal Display (LCD)
a. FREQUENCY MHz
·.Indicates the tuned frequency, in MHz, of the Receiver. Additionally, during
a
BITE test
sequence routine, a two-digit numerical error code
will
be displayed if BITE encounters any
failed test. (Refer to Section V, Maintenance.)
b. BFO kHz
Indicates selected BFO frequency in kHz with plus or minus sign to indicate direction of
offset from IF frequency. When in the CW mode and BFO CENTER is activated, the display
shows a single zero.
FAULT Indicator (LED)
A red Light Emitting Diode (LED) indicator lamp
will
be illuminated if there is a failure in
the first, second or BFO frequency synthesizers.
3.3
OPERATING INSTRUCTIONS
The RA6790/GM HF Receiver is internally controlled by a microcomputer which measures
and controls many more functions than previously available Receivers. Actual control of the Re-
ceiver's parameters is performed by control software contained in Eraseable Programmable Read-Only
Memory (EPROMs) within the Receiver. Additionally, a self-diagnostic feature (inclusion of Built-
In-Test-Equipment. BITE) allows the Receiver to perform self-test upon command for both local
(operator) and remote (computer) control, and report back status data through the addition of data
communications capability. While this may increase internal circuit complexity somewhat, actual
operating procedures become more simplified.
Additionally, the operator is able to further test the Receiver after BITE has finished its
analysis by depressing the appropriate pushbutton switches and observing selected Liquid Crystal
Displays (LCDs) on the receiver front panel. The operator can also verify proper operation by per-
forming options and system connections checks. tuning to local AM broadcasts, observing the signal
strength meter. and monitoring the audio from the Receiver.
Operation of the remote control module is verified by transmitting and receiving responses
with a remote device.
Before attempting to operate the Receiver, it is recommended that:
(1)
verification of all
options and systems connections installation be made in accordance with the procedures de·tailed in
St!ction II of this manual; (2) the Option Installation Check and System Interface Checks have been
performed as presented in Paragraphs 3.3.1 and 3.3.2 of this section; and (3) a thorough review of the
front-panel controls and indicators described in Paragraphs 3.1 through 3.2.11 of this section has been
accom plished.
3-6
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