DE
DANIELS
ELECTRONICS
2-8
MT-3 AM Transmitter Main Board Instruction Manual
2 . 3 . 4
PTT Time-Out-Timer
The PTT time-out-timer (TOT) is a relatively independent circuitry located on the Transmitter
Board. The TOT is powered from the cont9.5 Vdc supply (J34) and is programmable for
various time-out periods. The TOT input is normally high and in this state the timer is disabled.
When the input trigger level falls below +2.0 Vdc, the timer is activated, and the transmitter is
keyed. If the input trigger rises above +2.4 Vdc or if the time-out period is exceeded, the output
trigger will go high, disabling the transmitter. If the time-out period is exceeded, the TOT input
trigger must go high and then low again in order to rekey the transmitter.
The time-out duration is jumper selectable from 1 second to 8 hours. The table below shows the
time-out duration in minutes for the various jumper settings which are listed as enabled (E: jumper
shorted - in) or disabled (D: jumper left open - out). The standard factory setting of 5 minutes is
shown in bold type in the table below.
D = DISABLED (no solder jumper installed), E = ENABLED (solder jumper installed). Bold text
represents default settings.
TIME-OUT DURATION
(MINUTES)
JU26= E
JU26= D
JU26= E
J U 3 2
J U 3 1
J U 2 9
J U 2 8
JU27= D
JU27= E
JU27= E
E
E
E
E
0.01
0.01
0.01
E
E
E
D
0.02
0.03
0.01
E
E
D
E
0.04
0.06
0.02
E
E
D
D
0.08
0.12
0.05
E
D
E
E
0.15
0.23
0.10
E
D
E
D
0.31
0.47
0.19
E
D
D
E
0.62
0.94
0.38
E
D
D
D
1.25
1.88
0.75
D
E
E
E
2.5
3.75
1.5
D
E
E
D
5 . 0
7.5
3.0
D
E
D
E
10
15
6.0
D
E
D
D
20
30
12
D
D
E
E
40
60
24
D
D
E
D
80
120
48
D
D
D
E
160
240
96
D
D
D
D
320
480
192
