USKI-5 Universal Sequencer & Keying Interface
© Copyright 2015 QSK, llc
www.qskllc.com
Page 8
the last sequence has completed thereby missing the beginning of the next symbol. The time
duration of one “unit” in milliseconds (length of one “dit” or space between symbols within a
letter for normal weighting) is given by the formula
T
unit
=
1200
𝑊𝑃𝑀
ms
where WPM is the code speed in Words Per Minute. Since the time between two sequential
symbols within a letter is one unit, it is necessary for the sum of all START and END delays to
be less than the duration of one unit. As an example, for operation up to 50 WPM, the sum of
START and END delays must be less than 24 ms.
USKI-5 PREPARATION FOR USE
The USKI-5 is shipped without the output relays installed. Remove the four #1 Pozidriv screws
(a number #1 Phillips driver can be used with care) from either the front or rear panel and slide
out the circuit board. Install the desired relays into the sockets labeled RY1 through RY5. Make
sure of the relay orientation is as shown in figure 5. Pin #1 of each relay is indicated by a dot. If
relays are being used of different voltage/current ratings, make sure they are installed in the
correct channel positions.
FIGURE 5
It is a good idea to make note of what relay types are used and in which channels they are
installed. When all relays are in place, reassemble the sequencer.