Encoder Installation
025-9567E 35
It is possible to remotely enable or disable the keypad with a SPST switch wired across the
“A” position stakes of the jumper, but the length of the wire used should be kept under 23 cm
(9 inches). If the jumper is changed while power is applied then the RESET key may need to
be pressed to reconfigure the encoder action.
Display Scroll Enable/Disable
The display of the encoder may either be used to scroll the call number being sent or to
display only the last four digits of the call number. The jumper used to select the option is
jumper JP1 on the encoder board (702-0312). If scrolling is desired then jumper JP1must be
placed in the “scroll” or “A” position. If scrolling is not desired then jumper JP1 must be
placed in the “no scroll” or “B” position.
When scroll is enabled, the display of the call number being sent, if over four digits in length,
will marquee across the display at a rate of about three characters per second. Scroll enabled
will cause the encoder to add a considerable delay to its calling sequence and thus add to the
time that the encoder is on the air. When scroll is disabled, only the last four digits of the call
number being sent are displayed and no delay is added to the calling sequence.
Channel Busy Impedance
The impedance of each of the four channel busy inputs is selectable between high impedance
and low impedance using the jumpers, JP7 through JP10 on the encoder board (702-0312).
With a jumper in, the impedance is low and the input is pulled to incoming power (+12V) via
a 10 k resistor. With a jumper out, the impedance is high and the input is in series with a
3.3 k resistor to the base of a NPN transistor. Figure 7 shows a typical channel busy input.
A complete description of channel busy use may be found in the topic “Channel Busy
Monitor” on page 42.
+12 V
Ground
10 k
Jumper
0.001
F
Channel Busy
Input
3.3 k
Figure 7. Channel Busy Input Circuit
Audio Level Adjustment Range
The audio level adjustment range of the encoder is selectable between two ranges by the
presence or absence of the 120k ohm resistor, R23, at the top of the encoder board (702-
To Next Page
Loading...