Charles 7305-14 4W-2W, Руководство пользователя

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Section 730-514-202
3
1.5.3. Loopback (7305–19 Only)
2713Hz tone-activated loopback
Equal level loopback with gain of 0 to +/–24dB in 0.1dB steps
Loops back SF signaling and busies the E&M leads
Manual Loopback (MLB) switch
Tone Loopback Disable (DTD) switch
Front-panel-mounted LB LED that indicates loopback status
4/20 minute loopback time–out switch
Full 5-year warranty
2. INSPECTION
2.1 Inspect for Damages
Inspect the equipment thoroughly upon delivery. If the equipment has been damaged in transit, immediately re-
port the extent of damage to the transportation company.
2.2 Equipment Identification
Charles Industries’ equipment is identified by a model and issue number imprinted on the front panel or located
elsewhere on the equipment. Each time a major engineering design change is made on the equipment, the issue
number is advanced by 1 and imprinted on subsequent units manufactured. Therefore, be sure to include both
the model number and its issue number when making inquiries about the equipment.
3. APPLICATION GUIDELINES
The CFMs can be applied as Network Channel Terminating Equipment (NCTE) on special service circuits de-
scribed by any one of the following FCC Facility Interface Codes: (4W–4W) TL31M, TL31E, TC31M, TC31E,
TL32M, TL32E, TC32M, TC32E; and (4W–2W) TL11M, TL11E, TL12M and TL12E. The CFMs can be used in
central office or station applications and provides all necessary circuit functions to interface a 4-wire SF facility to
a PBX trunk circuit. See Figure 2, Figure 3 and Figure 4.
Figure 5 and Figure 6 illustrate typical 7305–14 and 7305–19 station and central office applications.
4. CIRCUIT DESCRIPTION
The CFMs provide signaling and transmission Interface between a 4-wire facility and a 2-wire or 4-wire circuit.
They also provide level control in both the transmit and receive paths. Refer to Figure 7 and Figure 8, the
7305–14 (Issue 2) and 7305–19 (Issue 2) block diagrams, while reading the following circuit description.
4.1 Transmit Voice Path
The transmit voice path of the CFMs is connected to the 4W/2W XMT STA at a fixed impedance of 600 ohms
(600 ohms in series with 2.15uF for 2W). The transmit voice path contains an attenuator stage (XMT ATN) pro-
viding up to 24dB of attenuation in 0.1dB steps. The XMT ATN stage is used to set the internal –16TLP (trans-
mission level point) from the 4W/2W XMT STA level.
The –16TLP output of the XMT ATN stage is routed through the XMT FET SWITCH to the XMT GN (transmit
gain) stage. The XMT GN stage provides up to 24dB of gain in 0.1dB steps. This allows the transmit line level to
be set from the internal –16TLP. The output of the XMT GN stage is transformer coupled to the XMT LINE and
provides 150, 600 or 1200 ohm impedance matching toward the cable facility. The net result of the XMT ATN and
XMT GN stages is to allow the CFMs to accommodate both line and station equipment levels b 7 and
–16dBm.