4.7.3
EXTERNAL METER TYPE
Two types of external carrier level meters are supported by the 9785. The nominal
±
10 dB range can
be mapped to either a 0 to 100
μ
A range, or to
±
1.0 Vdc. The desired meter type is selected using
jumper J3 on the Receiver Detector module. See paragraph 12.4.1 for more information.
4.7.4
TRANSMITTER FAIL ALARM, PICK-UP AND DROP-OUT
The transmitter fail detector (located on the Power Amplifier module) is designed to detect gross
failure of the transmitter, and therefore has a fairly slow response time. Depending on the dynamics of
the installed system, the actual settling time of the detector varies. For an ON/OFF carrier system, the
carrier is normally off, which is not a fail condition.
When the carrier is enabled, there is a delay before the detector signal becomes reliable. The AM logic
module allows for a delay between the carrier being enabled, and a transmitter fail alarm being issued.
This pick-up delay may be set for 3ms, 50ms, 100ms or 150ms using switches SW1-6 and SW1-7 on
the AM Logic module. The figure below illustrates various fail and status conditions. See paragraph
6.3.4 for more information.
Note:
All contacts shown in their
deenergized state.
TB7-1
TB7-2
TB7-3
Power Supply
Fail
Normally energized relay that falls
to the alarm state for power supply
failures
TB7-4
TB7-5
TB7-6
Transmitter
Fail
Normally energized relay that falls to the alarm state
when the logic module detects the Carrier Start input
is active, and does not detect an RF carrier output
Ck Bk
Test In
Progress
Check back status relay that is
energized, at the check back master
terminal, during the check back test
period.
TB8-1
TB8-2
TB8-3
Ck Bk
Test Fail
Check back alarm relay is deenergized, at the check
back master terminal, after a successful test
sequence. The alarm relay is energized, and latched,
after a test failure. The relay will reset only after a
successful check back test sequence.
TB8-4
TB8-5
TB8-6
Figure 4-3. 9785 Fail Conditions
RFL 9785
RFL Electronics Inc.
March 24, 2008
4-10
(973) 334-3100