Sine Systems RFC-1/B Instruction Book

/j\ WARNING!
L — - — 4 The dedicated control port, when enabled, is a two way
audio port with a superimposed source of 12 volts DC for applications requiring
"battery," such as telephone sets. However, when the RFC-1 is being used in
the dial-up" mode, this port is connected in parallel with whatever is attached
to the "LINE" j ack, normally a dial-up telephone line . If this is the case,
whatever is connected to the 'TELEPHONE" jack will also be connected to the
telephone line and should be FCC Part 68 registered.
The following is an example of the dedicated control port used with a dedicated line:
To "TELEPHONE" Jack
The line can be any length from a few feet to thousands of feet depending on the application
and tolerable series resistance. Fl and F2 should be 1/4 ampere fast blow fuses. VR1
through VR3 are 150 volt metal-oxide varistors (MOV's). Cl and C2 are 2 pF. 200 volt film
capacitors and are used to block the 12 volt DC "battery" source. If the dedicated line is
connected to a telephone set and the DC voltage source is desired to operate the DTMF
keypad, the capacitors may be eliminated. If the DC blocking capacitors are not used.
however, two conditions must be satisfied: first, no more than about 50 milliamperes DC
should be drawn from this port. This is an equivalent DC load resistance of about 240 ohms.
Second, no DC load, and only a high impedance AC load, should be present across this port
when the RFC-1 is being operated from a dial-up line. Both of these conditions will be
satisfied if an ordinary telephone is connected to this port and the telephone is left "on hook"
when not in use.
To interface the dedicated port to a radio or other "4 wire" communications link, the following
circuit is suggested:
3.00.2
Installation
page 5.13

Sine Systems RFC-1/B Specifications

General

Brand	Sine Systems
Model	RFC-1/B
Category	Remote Control
Language	English