USKI-5 Universal Sequencer & Keying Interface
© Copyright 2015 QSK, llc
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Page 5
(PTT, VOX, or use of internal CW keyer) must be prevented since there would be no
way for the sequencer to properly coordinate switching of the system components.
Transmitter external amplifier control output is however monitored in case of accidental
activation of the transmitter directly. In such an event, outputs for the transverter and
TMA are immediately switched into a safe transmit mode. Although this does not
guarantee that there will not be damage to the transverter or TMA, it can hopefully
provide some degree of protection.
Program (A) provides a transmit inhibit function. If initiated, sequencing will not start
regardless of the states of other inputs. If inhibit occurs after a start sequence has
begun, the program will immediately begin the end sequence from the last started output
channel. For example, if inhibit occurs during the delay TX_START_DEL_3, the program
will immediately switch off OUTPUT #3 (disregarding the time remaining of
TX_START_DEL_3) and will continue by switching off OUTPUT #2 and #1 in sequence
with delays TX_END_DEL_2 and TX_END_DEL_1 respectively as it would during a
normal
“key up” (or release of PTT) event. If transverter or remote TMA switching is
controlled by the sequencer, this provides the same necessary timing delays to protect
these devices during an inhibit condition just as in normal operation.
A station configuration suitable for control with Program (A) is shown in figure 2 (some
components shown are optional and may not actually be used). In this case, PTT and
CW keying is connected to inputs of the sequencer. Switching of all devices is thereby
controlled by the sequencer. Note the output numbers and the functions or devices they
control. The order is again chosen so that the TMA and transverter are first switched into
a safe transmit condition before the transmitter/transceiver is keyed and the reverse
order is followed when returning to receive. The actual order of output connections may
be different if other types of devices are being controlled.
FIGURE 2