ACCURATE ELECTRONICS INC
Practice Section 104003C Rev A January 2014
PO BOX 1654 97075-1654 8687 SW HALL BLVD 97008 BEAVERTON OR USA 503.641.0118 FAX 503.646.3903
This document contains proprietary information and is supplied for identification, maintenance, engineering evaluation or inspection purposes only and shall not be duplicated or disclosed without written
permission of: ACCURATE ELECTRONICS INC By accepting this document the recipient agrees to make every effort to prevent unauthorized use of this information.
6
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.
A.
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.
B.
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.
C.
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.
D.
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.
E.
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.
A.
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.
B.
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.
C.
Again send 1000Hz tone at the specified level. Request that
personnel at the distant (facility-side) receive location measure
and record the 1000Hz level.
D.
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
any difference in levels exists, insert or remove gain via the front-
panel TX LEVEL switches to obtain the required level.
E.
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. These
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
adju16dB, +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)