Q.5.4.3.4 Type 3 Fault Gate: U23-8
A Type 3 fault occurs when repeated VSWR “hits” lower
transmitter power. A remote “Type 3 Fault” status indication is
provided at U23-8 and invertor U8-6.
Q.5.4.4 VSWR Status Indication Circuits: U38-3/11, U37-
11, U39-2, DS8
The operation of the Bandpass Filter and Antenna VSWR
“Status Indicate” circuit is identical (U38-6/8, U37-8, U39-4,
and DS16). The Extended (remote) “Status Indicate” logic
HIGH signal is present if the Pulse Stretch one-shot “NOT-Q”
output goes LOW or if the Repeated VSWR Latch “NOT-Q”
output goes LOW. The one-shot and latch outputs are OR’ed by
U38-11 then inverted by U38-3 to provide the VSWR-H output.
A single VSWR “hit” will send a 0.5 second logic HIGH pulse
to the External Interface, and a latched VSWR output will
remain HIGH until it is reset.
A GREEN VSWR status indication occurs when there is no
VSWR Fault pulseor Latched VSWR fault. The NOT-Q outputs
of Pulse Stretcher U12B and Latch U24A are both HIGH (pins
12 and 6 respectively). Both inputs 1 and 2 to gate U38 are
HIGH, the output is HIGH, and the GREEN LED is on. If either
a VSWR Pulse or Latched output causes an input to U38 to go
LOW, U38-3 output goes LOW and the GREEN LED extin-
guishes.
Figure Q-4. Type 2 Fault Logic, Simplified Diagram
8172099036
DX-25U
Q-14 888-2297-002 Rev. R: 11-11-96
WARNING: Disconnect primary power prior to servicing.
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