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| What is used to isolate a frame relay circuit? |
| Frame relay is a communication service from an end user to the network. The isolation card used depends on the physical layer circuit provided by the network. This could be an HDSL circuit (751339R2), a T1 circuit (751329), a fractional T1 circuit (751329) or 56k DDS circuit (7501-24). |
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| What should be used to isolate a 911 2-wire CAMA circuit? |
| A 7501-16 must be used. The CO might be looking for a negative voltage referenced to the ground. If this is the case, a proper Modification Bulletin must be implemented: #7501-15-40 (7501-16A), #7501-15-41 (7501-16B) or #7501-15-42 (7501-16C). |
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| What should be used to isolate an E&M line? |
If it uses a FX line, a 751317, a 7501-16 or a 751321 should be used. If it is a 4-wire E&M line, the following will be required: •One 7501-24 card to isolate the TX and RX line
•One 7501-16 card connected between GND and E lead
•One 7501-16 card connected between GND and M lead
A Positron technician should be contacted for further information.
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| What should be used to isolate a payphone? |
It depends if the phone uses battery reversal or not, and if it uses tones or ground signaling.
If it is an older phone using ground signaling, the only way to isolate it is by using a setup made of two 7501-16 cards called “the coin telephone setup”. For further information on this setup, a Positron technician should be contacted.
If it is a phone using tones and no battery reversal, the 751317, 751321 or 7501-16 cards may be used. The 751321 cards are the least expensive.
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| What card should be used to isolate an RS-485? |
| There is no Teleline for an RS-485. The only way to isolate such a link is to first transform it into a POTS line using a modem at both ends, and then using a 751317, 751321 or 7501-16 to isolate the line between the modems. |
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| What card should be used to isolate an AC pilot wire? |
A 7501-15 card should be used. There are three different models that are powered from different voltages: 7501-15A, 7501-15B and 7501-15C.
•7501-15A is powered from a floating 130 Vdc source, usually station batteries.
•7501-15B is powered from a grounded -24 Vdc source.
•7501-15C is powered from a floating -48 Vdc source, usually station batteries.
All cards can accept line voltages up to 150 Vdc and line currents up to 100 mA with a maximum of 5W (current times voltage).
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| Does Positron make power supply cards that fit the full size slots of the shelves? |
| Positron used to make a 7501-35 card that would power circuit cards within the older and the newer version of the 3, 5 and 8-card shelves. In order not to waste a circuit slot, in the 5 and 8-card shelves, the 751313, 751316 and 751324 power supplies should be used in the dedicated slots of the shelves, which do not waste a full size circuit slot. Because the 3-card shelf does not have the dedicated power supply slot, an external power supply to the shelf should be used. |
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| Does Positron make 130 Vdc to 48 Vdc power supplies to power station side loop-back equipment? |
With the older shelves, the physical makeup of the station motherboard of the shelf does not allow a 48 Vdc to originate on the shelf and be routed outside the shelf. In addition, there is no connection on the back plane of the shelf to allow an output of 48 Vdc from a supply to be connected to the motherboard. With the new version of the 5 and 8-card shelves, it is possible to supply a 48 Vdc power to power the station side loop back equipment. For the 5-card shelf, refer to figure 4 of the 751112/1 installation guide. For the 8-card shelf, refer to figure 4 of the 751109/13 installation guide.
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| Does ADC make HV isolation jacks that allow bridging? |
| No. Bridging is a severe safety issue. It would require special protection equipment at both locations, and would create confusion during installation. In addition to that, I.E.E.E. standard 487 strictly disallows bridging of any circuit using any means. |
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| Can the clear plastic cover covering the HV jacks be ordered so that one doesn't have to pull all the plugs in order to get the plastic off? |
| No, the wiring of the CO cable to the shelf cable via the isolation jacks should be done once. Then, all future changes should be done at a cross connect box or at the 300 V point splice. This is a safety item and a maintenance item. This is part of the design of the isolation. If constant rewiring on the jacks is being done, the cable pairs will become brittle and break. In addition, it is far safer to wire the jacks than make the 300 V point connection. That way one can work the isolation jack connection barehanded, assuming the dedicated cable is open and the pairs are cleared at the 300 V point splice. |
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