Vega C-6124, Техническое руководство

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49 Vega’s C-
6124
6.3.3 FOUR WIRE MODE
Each TLM comes standard with a jumper selectable 2 or 4 wire option. Note: The TLM is shipped in the 2-
wire mode. 4-wire mode is accomplished by the following jumper positions:
Jumper Position
JP10 B
JP11 B
The RX pair is now on pins 3 and 6 of the line jack and the TX pair is on pins 4 and 5. Once the transmit and
receive paths are separated the impedance of each side must be set.
6.3.3.1 RX SIDE SETTINGS
4-WIRE Operation:
The RX side is jumper selectable for a 600 ohm impedance or 10k ohm impedance. If only one TLM is on the
line (no parallel consoles) then place JP12 in the A position for a 600 ohm line impedance. If more than one
TLM’s are on one line then place JP12 on one console in the A position and all other consoles in the B
position. Each console added to the system will result in line loss. The following chart gives an indication
as to how much loss can be expected. The first console in the system is set for an impedance of 600 ohms
out (approximately). Each console added to the system there after is set with an impedance of 10k ohms. As
the chart shows, the more consoles that are added, the lower the line impedance and the greater the loss in
audio level.
JP12 individual total line line
Console added position impedance impedance loss (db)
1 A 584 584 0
2 B 10k 552 -.48
3 B 10k 523 -.95
4 B 10k 497 -1.4
5 B 10k 473 -1.8
6 B 10k 452 -2.2
See the section on level adjustments to make up for any loss incurred.
2-WIRE Operation:
/In 2-wire operation JP12 should be in the B position for 10K ohm line impedance.
6.3.3.2 TX SIDE SETTINGS
Two jumpers on the transmit pair allow a degree of control over the output impedance. The following chart
lists the jumper positions for each card depending on how many consoles are placed in parallel. All cards
should have the same jumper settings.
Consoles in TLM TLM Individual TLM
Parallel JP8 JP9 Output Impedance
1 B A 600 ohms
2 A A 1200 ohms
3 B B 1800 ohms
4 A B 2400 ohms
6.3.3.3 TRANSMIT MONITOR
In a 4 wire system the transmit line may be monitored by the receive circuits by placing JP1 in the B position.
See section 6.4.24 for information on adjusting the monitor level.