ACCURATE ELECTRONICS 104003C Manual - Page 6

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ACCURATE ELECTRONICS INC

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PO BOX 1654 97075-1654 8687 SW HALL BLVD 97008

FINAL ALIGNMENT VERIFICATION

3.19 In this final alignment verification procedure, the 104003C is placed

into service, signal level measurements are taken, and the front-panel TX

LEVEL and RX LEVEL switches are reset, as required, to meet the levels

specified on the CLR card. Attenuation or gain introduced at this time does

not affect the equalization characteristics that may have been previously

introduced via the equalized gain switches. It is strongly recommended

that no 1000Hz level adjustments be attempted with the equalized gain

switches.

RECEIVE-CHANNEL

3.20 To perform the receive-channel's final alignment verification, proceed

as follows:

Note: If receive-channel equalization is not required, request that the distant

location only send 1000Hz tone at the specified level and omit step B.

Connect a properly terminated TMS (receive) to the RX IN MON

jack and insert an opening plug into the RX IN jack. Request that

the distant location send 1000Hz and 3000Hz tone at the level

specified on the CLR card. Verify that the tone is present and

record these levels.

If receive-channel equalization and gain were determined in the

preliminary alignment procedure (paragraphs 3.13 through 3.15),

omit this step and proceed to step C. If not, determine the type of

cable the module interfaces and, with the 1000Hz and 3000Hz

levels measured in step A, perform the equalization (if required)

and gain procedures in accordance with paragraphs 3.13 through

3.15.

Disconnect the TMS and remove the opening plug. Connect the

TMS (receive) to the RX OUT jack. Request that the distant

location again send 1000Hz tone at the level specified on the CLR

card.

Determine the difference (in dB) between the measured 1000Hz

receive output level (step C) and the receive output level specified

on the CLR. If any difference in levels exist, insert or remove

gain via the front-panel RX LEVEL switches to obtain the

specified receive output level.

To complete receive-channel verification, perform a frequency

run, measuring levels at appropriate intervals from 300to 3000Hz.

If the measured levels meet the desired frequency response

characteristic, the equalizer is properly set.

TRANSMIT CHANNEL

3.21 To perform the transmit-channel's final alignment verification, proceed

as follows:

Note: If transmit-channel equalization is not required, insert 1000Hz tone

into the TX IN jack at the specified level and omit steps B and C.

Connect a properly terminated TMS (transmit) to the TX IN jack.

Send 1000Hz and 3000Hz tones at the specified level. Request

that personnel at the distant facility-side (receive) location

measure and record the level of each tone.

If transmit-channel equalization and gain were determined in the

preliminary alignment procedure (paragraphs 3.16 through 3.18),

omit this step and proceed to step C. If not, determine the type of

cable the module interfaces and, with the 1000Hz and 3000Hz

levels measured in step A, perform the equalization (if required)

and gain procedures in accordance with paragraphs 3.16 through

3.18.

Again send 1000Hz tone at the specified level. Request that

personnel at the distant (facility-side) receive location measure

and record the 1000Hz level.

Determine the difference (in dB) between the distant facility-side

(receive) location's specified 1000Hz input level and the level

measured in step C (or step A if equalization is not required). If

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Practice Section 104003C Rev A

BEAVERTON OR USA 503.641.0118

any difference in levels exists, insert or remove gain via the front-

panel TX LEVEL switches to obtain the required level.

To complete transmit-channel verification, perform a frequency

run, measuring levels at appropriate intervals from 300 to

3000Hz. If the measured levels meet the desired frequency-

response characteristic, the equalizer is properly set.

4. CIRCUIT DESCRIPTION

4.01 This circuit description is designated to familiarize you with the

104003C Line Amplifier with Loopback module for engineering and

application purposes only. Attempts to test or troubleshoot the 104003C

internally are not recommended. Procedures for recommended testing and

troubleshooting in the field are limited to those prescribed in section 7 of this

Practice. Please refer to Figure 1 (see page 10) of this Practice, as an aid in

following the circuit description.

4.02 The power supply in the 104003C is a simple series voltage regulator

that uses a zener diode as a reference source. A series diode in the negative

input lead protects the circuit against reversed input power connections, and

a transorb between input battery and ground limits high-level supply transient

to a safe level.

4.03 The transmit and receive sections of the 104003C are identical. Input

and output transformers are used to interface external circuits.

transformers also derive simplex leads at all four ports (transmit and receive,

input and output). A secondary winding of each transformer is connected to

the channel amplifier.

4.04 Clamping diodes limit the amplifiers' input and output voltages to

internal power potentials and provide surge protection at each of the four

ports. Each channel's amplifier section is controlled by an option switch that

introduces either negative feedback to provide loss or positive feedback to

provide gain. The precise amount of gain or loss selected is via the front-

panel TX and RX level switches. The output of each channel amplifier also

feeds a series connected equalized-gain amplifier that provides up to 7.75dB

of slope equalization via DIP switches on the module's front panel.

TONE-ACTIVATED LOOPBACK

4.05 The input for tone-activated loopback is obtained from the output of the

receive equalizer. The tone is detected by a 2813Hz filter circuit, preceded

by a limiter for signal-to-guard control. The output of the 2813Hz filter, at

resonance, starts the 1.4-second timing cycle. The logic circuitry determines

the status of the LB relay and sets the timer for 1.4 seconds if the LB relay is

released. The LB relay remains activated until a second loopback tone is

placed on the modules' receive pair for longer than 0.7 second.

LOCAL DC LOOPBACK

4.06 Local application of a ground potential to pin 1 operates relay LB

directly, resulting in the activation of loopback. The LB relay will remain

operated (looped) until the ground potential is manually removed from pin 1.

LOOPBACK LEVEL

4.07 A prescription-set amplifier/attenuator circuit is located in the loopback

path between the receive and transmit channels. This circuit provides for the

adjustable +16dB, +9dB, -16dB or –23dB loopback level.

5. MECHANICAL OUTLINE

5.01 See FIGURE 2.

6. SPECIFICATIONS

6.01 Electrical

Note: Transmit-channel and receive-channel specifications are identical.

Facility/Terminal Port Impedances:

Switchable 1200, 600, or 150 ohms, balanced

Flat Gain or Loss: -24 to +24dB in 0.1dB increments, prescription-set

Via front-panel switches (gain or loss determined

by switch option)

January 2014

FAX 503.646.3903

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