EF-1
INTERFACE
INSTRUCTION MANUAL
2000 Clear-Com Intercom Systems
All Rights Reserved
Part Number 710540
Clear-Com Intercom Systems
4065 Hollis Street
Emeryville, CA 94608-3505
U.S.A
Clear-Com is a registered trademark of Clear-Com Intercom Systems.
The Clear-Com Logo is a registered trademark of Clear-Com Intercom Systems.
Matrix Plus is a registered trademark of Clear-Com Intercom Systems.
RTS is a registered trademark of Telex Communications, Inc.
Fiber Options is a registered trademark of Fiber Options, Inc.
CONTENTS
QUICK START
OPERATION
Description
Front Panel
Rear Panel
INSTALLATION
Connecting the EF-1 to a Modem
Applications
Levels
Nulling
Adjusting the Null
Troubleshooting Tips for Nulling
Internal Adjustments
EF-1 INTERFACE
1-1
2-1
2-1
2-7
2-9
3-1
3-1
3-3
3-4
3-5
3-6
3-7
3-8
i
TRANSMISSION METHODS
4-1
Direct Connection
Fiber-optic
Other Methods
4-1
4-2
4-4
MAINTENANCE
Troubleshooting Tips
Block Diagram
Component Layout
Bill of Materials
GLOSSARY
6-1
SPECIFICATIONS
7-1
CLEAR-COM LIMITED WARRANTY
8-1
Factory Service
Warranty Repair
Non-Warranty Repair
ii
5-1
5-1
5-6
5-7
5-8
8-2
8-3
8-3
EF-1 INTERFACE
1 QUICK START
• Follow these
instructions to quickly
get the system up
and running.
EF-1 INTERFACE
1. Unpack the unit(s) and inspect for any damage that may have occurred during
shipping.
2. Attach the connection diagram label to a convenient surface, such as the bottom of the
EF-1 unit.
3. Wire the included DB-15 connector to the correct connectors for the additional
interface being used (fiber-optic, direct connection to another EF-1, etc.). Take care to
wire to the correct pin assignments, including selection of Clear-Com or RTS-type
operation. Follow the manufacturer’s recommendations for cable type.
4. Repeat for each location.
5. Connect the respective party-line systems at each location to an EF-1 unit.
6. If there is a proper RS-422 data connection, the amber LED will illuminate steadily.
7. Plug in the test earpiece and set the null for each location using the procedure on page
3-6 of Chapter 3, “Installation.” Adjust the null on other stations and beltpacks if
required.
8. Adjust send and receive levels at each location as described on pages 3-4 of Chapter 3,
“Installation.”
1-1
2 OPERATION
Thank you for choosing this Clear-Com Intercom Systems product.
• EF-1 units connect
two-wire intercom
stations or systems
together over various
transmission media.
The EF-1 four-wire interface is a flexible and powerful tool for connecting two-wire
intercom systems or stations together over various transmission media other than typical
shielded-pair microphone cable.
Please read this manual completely to better understand the functions of this product. For
questions not addressed in this manual, you can contact your dealer or distributor, or you
can contact the Clear-Com service department directly. Our applications support and
service people are ready to help.
DESCRIPTION
The EF-1 converts a channel of standard or TW party line to four-wire audio and, at the
same time, converts a DC-voltage call signal or 20-kHz call signal to RS-422 data. This
four-wire audio and RS-422 data can then be sent to a fiber-optic converter (modem);
over copper, unshielded twisted-pair (UTP) cable such as Category 3 or 5; or it can
2-1
EF-1 INTERFACE
simply be used as an excellent stand alone two-wire to four-wire converter. In most cases
though, EF-1 units will typically be used in pairs, because once the signal is converted to
go over the chosen transmission medium, it must be reconverted to two-wire mode to
properly connect to the party-line system or station at the other end of the line. The EF-1
obtains its DC operating current from the local party-line connection on pin 2 of the
XLR connector. This current is not conducted between EF-1 units, so each EF-1 must be
powered by an intercom line as shown in Figure 1.
Party-Line Intercom
3
3
3
EF-1
3
Fiber Modems
DB15
EF-1
DB15
3
Party-Line Intercom
3 3
Cat 3 or Cat 5
Twisted Pair
3 = Male 3-Pin XLR
3 = Female 3-Pin XLR
Figure 1: Example Configuration
EF-1 INTERFACE
2-2
Call signaling can serve as more than simply a visual indicator. A call signal can be used to
activate relays and trigger functions in other connected Clear-Com equipment. The
Clear-Com TW-40 two-way radio interface and KB-212 speaker station use this feature.
Imagine a party-line (PL) system connected to a fiber-optic system over a 1-kilometer
fiber as shown in Figure 2. At the other end of the fiber there is another EF-1 unit and PL
system with walkie-talkies interfaced through a TW-40. The EF-1 allows the people on
the first PL system to communicate with the people on the walkie-talkies over a kilometer
of fiber, with the call signal determining transmit or receive operation.
Party-Line Intercom
3
3
EF-1
3 DB15
Fiber Modems
EF-1
DB15
3
PK-5
3 3
Base
Walkie
TW-40 Talkie
Remote
Walkie
Talkies
3 DB9
3
3 = Male 3-Pin XLR
3 = Female 3-Pin XLR
Figure 2: Example Configuration
2-3
EF-1 INTERFACE
NOTE: The terms modem, codec, and interface all refer to devices that convert one
type of signal for transmission or reception to a different type of signal.
• The ES-1 can be a
stand-alone device or
it can be mounted on
utility rack shelves.
Because of the EF-1’s low profile and compact size, it can be used either as a stand-alone
device or it can be mounted on utility rack shelves. Up to three units will fit
horizontally in one-rack unit (1RU) of space and will offer sufficient vertical clearance
to accommodate a variety of mounting methods. While the EF-1 may be used as a
single ended four-wire-to-party-line interface with excellent results, it is uniquely
equipped to work in point-to-point pairs. Much of the discussion in this manual
address the issues of operation in this latter mode.
Due to the superior nulling capability of the EF-1, more than a single pair of EF-1 units
can be used to link various locations to a single channel.
As an example consider the following scenario: The three Channel A ports of an
MS-232 main station are each connected to an EF-1. (For an illustration, see Figure 3.)
Each of those three is in turn connected to a fiber-optic modem and sent through fiber
to another fiber-optic modem, EF-1 unit, and party-line system at the three remote
destinations. All four locations are now sharing the same channel, linked through fiber,
with a total of six “nulls” on the channel. While the nature of two-wire to four-wire
hybrids may limit the maximum number of external two-wire party lines that can be
EF-1 INTERFACE
2-4
Configuration Example
Party-Line Intercom
3 3 3
EF-1
3 DB15
EF-1
3 DB15
Fiber Modems
Party-Line Intercom
EF-1
DB15
3
EF-1
DB15
3
3
PK-5
3 3
3
EF-1
3 DB15
EF-1
DB15
3
PK-5
3 3
3
3 = Male 3-Pin XLR
3 = Female 3-Pin XLR
Figure 3: Example Configuration
2-5
EF-1 INTERFACE
combined, six EF-1 units on a common channel, properly nulled, should generally
provide a stable system.
Because the EF-1 will be used with a wide variety of third-party systems and devices, it is
not possible to address all the variables of setups and transmission methods. The key
point is that the modem, multiplexer, or converter for the transmission medium (the
system that the EF-1 connects to via the DB-15) must accept line-level (-15dBV to
+4dBV) four-wire audio and, if call signal is desired, RS-422 data.
EF-1 INTERFACE
2-6
FRONT PANEL
• Front panel controls
include: send,
receive, and sidetone
null adjustments.
• Do not force the level
control and nulling
trimpots past their
stop points as this
will damage them.
Figure 4: Front Panel
Local Send controls the audio signal level from the local two-wire intercom (the system
connected to this EF-1) to the audio out of the four-wire I/O. This control has a range of
±12 dB.
Local Receive controls the audio signal level from the audio in of the four-wire I/O to the
local two-wire intercom. This control has a range of ±12 dB.
2-7
EF-1 INTERFACE
• The Data LED has
four modes.
Sidetone Null Adjustment This set of three trimpots includes R=Resistance,
L=Inductance, and C=Capacitance. These compensate for each component of the line
impedance, providing the best null possible. To prevent damage to the level control and
nulling trimpots, do not force them past their stop points.
Power LED This green LED will illuminate when the EF-1 is receiving power from pin 2
of the party-line XLR connection.
• A slow blink on the
Data LED means
that a test earphone
has been plugged
into the test tone
jack and the nulling
test tone is on.
EF-1 INTERFACE
Data LED This amber LED has four modes. The first three relate to call signal data:
1. ON- A successful data link has been established with the other EF-1.
2. OFF- There is no data connection at this unit.
3. RAPID BLINK- There is data connection at this unit, but a “break” condition is
present. Depending on the modems used, this can indicate a problem at the far end.
4. SLOW BLINK- A test earbud or headphone has been plugged into the test tone jack
and the nulling test tone is on.
Call signals will not be passed unless the LED is steadily illuminated. Audio is still
transceived by a connected unit.
2-8
REAR PANEL
• Either or both
intercom jacks may
be used for
connection to the
local system.
• The EF-1 connects to
additional interfaces
or converters through
the DB-15 connector.
Intercom
Figure 5: Rear Panel
• There is one male and one female three-pin XLR jack for connection to the party line.
• Either or both jacks may be used for connection to the local system. The EF-1
may also be inserted “in-line” on a channel: the party-line signal comes in the first jack,
continues out the second, and proceeds to the next device in the party-line chain.
NOTE: Each (local) party-line channel must have one, but only one, termination. (See
Figure 6 on page 3-2.)
2-9
EF-1 INTERFACE
Data/Audio
• The EF-1 connects to additional interfaces or converters (or directly to another EF-1)
through the DB-15 connector. Two pins each are dedicated to audio in, audio out, data
in, and data out.
• There are also connections for audio and data shields if present in the wiring.
• Shorting pins 8 and 15 together options the unit to respond to 20-kHz call signal
instead of DC voltage and adjusts audio levels for connection to RTS-TW lines.
EF-1 INTERFACE
2-10
3 INSTALLATION
CONNECTING THE EF-1 TO A MODEM
• To connect the EF-1
to a modem, wire the
DB-15 plug to the
modem’s audio and
data connectors.
• A stick-on label with
pin-out assignments
is included.
3-1
The first step in connecting the EF-1 to a fiber-optic modem is to wire the DB-15 plug to
the appropriate connector(s) for that modem.
This may be terminal blocks, XLR jacks, or co-axial connectors. Four-pair twisted cable
or shielded-pair cable may be required. Check the operations manual for the modem. For
unshielded, twisted-pair cable (UTP), Category 3, 5, or higher is acceptable if used within
the distance limitations specified by the modem’s manufacturer for this application.
The four pairs of cable used for full operation include one each for audio in and out and
one each for RS-422 data in and out.
Take care to wire the DB-15 pins correctly. For added reference, the illustration on page
3-2 (Figure 5) shows the pin-out configuration. A stick-on label with the pin-out
assignments has been included for the user’s convenience. Attach this in a convenient
location.
EF-1 INTERFACE
Intercom Line
4-Wire Audio / Data
8
XLR-F
XLR-M
7
15
1
2
2
1
3
3
+ 30 VDC Power
Intercom Line
Intercom Ground
6
14
5
13
4
12
3
11
2
10
1
9
Jump for TW
Open for C-C
(Not Used)
- RS-422 Local Receive
- RS-422 Local Transmit
+ RS-422 Local Receive
+ RS-422 Local Transmit
RS-422 Receive Shield
RS-422 Transmit Shield
4-Wire Audio Input Shield
4-Wire Audio Output Shield
- 4-Wire Audio Input to PL
- 4-Wire Audio Output from PL
+ 4-Wire Audio Input to PL
+ 4-Wire Audio Output from PL
Figure 6: EF-1 Pinout Configuration
EF-1 INTERFACE
3-2
• To confirm the
proper data
“handshake,” you
can send a call
signal.
After wiring the DB-15 to the appropriate connectors, follow these steps to connect the
EF-1 to a modem:
1. Connect the local party-line channel to the EF-1.
2. Check to see that the EF-1 is receiving power by checking the green Power LED (the
“on” light). If there is a powered EF-1 properly connected at the other end of the
transmission line, the amber Data LED should also illuminate within a second or two.
This confirms a proper data “handshake” between the two units.
3. Send a call signal and check that it is received at the distant intercom system.
4. Adjust nulls, and then check audio levels as required.
5. Repeat as necessary for each EF-1 in the system.
Applications
An EF-1 may be used in a wide variety of interface situations. Even if the call signal
translation is not required, it is an excellent four-wire to party-line interface for use with
many types of intercom and audio equipment in the following situations:
• Any four-wire audio source and destination to party line.
• Four-wire matrix port to party line (no call signal).
• PL system direct to PL system. Requires two EF-1 units (could be different types of PL
on each end).
• PL system to PC sound card.
3-3
EF-1 INTERFACE
For use with a Clear-Com Matrix Plus 3 system, connect the four-wire audio directly to a
port. Configure that port for “four-wire” operation. Operation with Clear-Com Matrix
Plus 2 systems will be similar.
• Connect the four-wire
audio directly to a
port when you use a
Clear-Com Matrix
system.
For use with RTS-TW equipment, the DB-15 must be wired differently. When used with
all but the very early RTS-TW equipment, whichever audio channel is wired to pin 3 of
the EF-1’s XLR connector will connect through the DB-15. (Older units do not offer
power on both channels; therefore a pin/channel reversal would result in no power
supplied to the EF-1). The audio channel carried on pin 2 of a TW line (Clear-Com or
RTS) will not be connected through the EF-1; however, it will not be negatively affected.
LEVELS
• A combination of
controls affects the
listen levels.
EF-1 INTERFACE
A combination of controls affects the listen levels at any station: the sidetone and volume
at the users’ stations or beltpacks; the receive level of the local EF-1; and the send level of
the remote EF-1.
Adjust the PL send and receive levels as appropriate for the external PL system and
listening conditions. The controls will typically be between 10 o’clock and 2 o’clock,
roughly in the 0-dBV range at the four-wire interface. If different intercom brands are
used on opposite ends of a pair of EF-1 units (RTS and Clear-Com for example), the
controls may need to be adjusted outside of the normal range. Otherwise, more extreme
settings could indicate a problem elsewhere in the system.
3-4
• Null is affected by
the local party-line
system.
Level settings will differ slightly if the EF-1 is used with RTS-TW intercoms, as the
nominal audio levels for that system are slightly higher than Clear-Com or compatible
systems (about 4-8 dB). RTS and Clear-Com may be freely mixed on a channel,
including call signaling, though the maximum number of EF-1 units able to share a
channel may be reduced. RTS levels and call signals are selected by jumpering together
pins 8 and 15 of the DB-15 connector.
NULLING
• The test tone will
activate when you
plug the earphone
into the 1/8 in. jack
on the front panel.
“Sidetone” is the sound of the operator’s own voice in his or her headset or speaker. With
interfaces, it is necessary to “null” (minimize) the sidetone when external party lines are
connected over the secondary transmission media. Ideally, there should be no portion of
the talk signal in the listen signal. Every EF-1 sharing a channel in a system should be
nulled consecutively. Null is also referred to as “hybrid null.”
Null is affected by the local party-line system connected to the EF-1, not the secondary
interface. The null circuit is effective on line lengths between 2 feet and 4,000 feet
(1.64 m–1220 m) with impedances in the range of 120 to 350 Ohms and can reduce
local audio in the received signal by more than 30 dB over the frequency range of 200 Hz
to 8 kHz.
The EF-1 includes built-in nulling circuitry with a test-tone generator and is shipped
from the factory with an accessory earphone. Plug the earphone into the 1/8 in. (3.5 mm)
3-5
EF-1 INTERFACE
• You may need to
re-null the EF-1 if the
configuration of the
local party-line
changes substantially.
• Continue the
adjustments until the
test tone is virtually
inaudible.
EF-1 INTERFACE
jack on the front panel. This will automatically activate the test tone (and the amber data
LED will blink slowly). The earphone monitors the output of the nulling circuit. The test
tone will be sent to any active stations and other EF-1 units on the channel, so remove
headsets, adjust volumes, and turn off speakers as appropriate.
Adjusting the Null
Normally, the following adjustment is made once during installation. (If the
configuration of the local party-line system changes substantially, it may be necessary to
re-null the system for optimum performance.)
1. Connect all the local party-line devices for that channel together and to the EF-1.
2. Plug into the front-panel earphone jack labeled “test.” You will now hear a steady
200-Hz tone through the earphone.
3. Adjust the “R” control until the tone is at its minimum.
4. Adjust the “L” control until the tone is at its minimum.
5. Adjust the “C” control until the tone is at its minimum.
6. Because these controls interact with each other, you will need to repeat steps 3, 4, and 5
several times before fully minimizing the test tone.
7. Continue these adjustments until the test tone is virtually inaudible.
3-6
• The transmit level at
the local EF-1 will
affect the listen level
at the remote EF-1.
If a complete or almost complete null cannot be obtained, is likely that there is a problem
with either the wiring of the external party line or with one of the other devices attached
to the external party line. The next section provides troubleshooting tips.
8. Unplug the earphone when the nulling operation is complete.
Troubleshooting Tips for Nulling
• If the “R” control is turned fully counterclockwise, the line has multiple terminations
or a resistive load.
• If the “R” control is fully clockwise, then the line is unterminated.
• The “C” control
compensates for
cable capacitance
and is line-length
dependent.
• The “L” control compensates for the low frequency inductive and capacitive elements
of the external party line. If the “L” control is fully turned in either direction, it is likely
that there is a problem in the external party line. With a Clear-Com party line
connected, the “L” should be slightly to either side of the mid-pot position.
• The “C” control compensates for cable capacitance and is line-length dependent. If
fully counterclockwise, this indicates a very short line (<10 feet or < 3 m). This is a
valid setting for a short line.
• If “C” if fully clockwise, this indicates an excessively long line (>4000 feet or >1200 m).
• Remember, you are adjusting the null to/from the local party-line system. Only the
transmit send level at the local EF-1 will affect the listen receive level at the remote
EF-1.
3-7
EF-1 INTERFACE
INTERNAL ADJUSTMENTS
The only user-performable internal adjustment is selection of the baud rate for the
RS-422 data.
The factory-set baud rate for the RS-422 data is 19.2 kilobits per second (19.2 kbps). For
certain transmission schemes, the baud rate is internally selectable for 2400, 4800, or
9600 bits per second. Additional fixed settings are: 8 data bits; 1 stop bit; no parity.
• The only internal
adjustment is baud
rate for RS-422 data.
NOTE: Accessing the baud rate jumpers inside the EF-1 requires removal of the cover.
Use the following procedure:
Removing the cover of the EF-1
Three tools are required for this procedure: a #2 Phillips screwdriver, a 3/16 in. nut driver,
and a flat-bladed screwdriver with a blade width of approximately .075 in. (1.9 mm).
Follow these steps:
1. Disconnect all cables.
2. Remove the four sheet metal screws on the back and sides.
3. The XLR jacks have special locking tabs to secure them to the housing. These must be
released before the cover can be removed. Use a very narrow-tipped screwdriver, like a
“greenie.” Insert it into the slot inside the XLR jack and twist the release lock
counterclockwise for approximately 1/4 turn. Repeat for each jack.
4. Remove the two 3/16 in. (4.76 mm) hex-head jack screws on the DB-15.
EF-1 INTERFACE
3-8
• To set a jumper to
the closed position,
plug it onto both
pins.
• To set a jumper to
the open position,
plug it onto only one
of the pins.
5. Slide the cover back until the DB-15 and XLR jacks are clear.
6. Lift off the cover.
7. Make the necessary adjustments of jumpers P3 and P4 (shown in the following table).
To set a jumper to the closed position, plug it onto both pins. To set a jumper to the
open position, plug it onto only one of the pins.
Baud 1
Baud 2
Rate
Open
Open
19.2 kBaud
Closed
Open
9.6 kBaud
Open
Closed
4.8 kBaud
Closed
Closed
2.4 kBaud
8. Reverse steps 1 through 6 for reassembly.
NOTE: The potentiometer (R13) is used to factory tune the 20-kHz call-signal detection
circuitry. It should be adjusted only by qualified service personnel.
3-9
EF-1 INTERFACE
4 TRANSMISSION METHODS
DIRECT CONNECTION
There are many instances where twisted-pair cable is available for audio connections. This
wiring is typically found in unused telephone cable in or between buildings. Figure 9
illustrates twisted-pair wiring connections.
EF-1
EF-1
DB-15 Pins
Twisted Pair Wiring
DB-15 Pins
- RS-422 Transmit
6
14
- RS-422 Receive
+ RS-422 Transmit
5
13
+ RS-422 Receive
- RS-422 Receive
14
6
- RS-422 Transmit
+ RS-422 Receive
13
5
+ RS-422 Transmit
2
10
- 4-Wire Audio Input to PL
- 4-Wire Audio Output from PL
1
9
+ 4-Wire Audio Input to PL
- 4-Wire Audio Input to PL
10
2
- 4-Wire Audio Output from PL
+ 4-Wire Audio Input to PL
9
1
+ 4-Wire Audio Output from PL
+ 4-Wire Audio Output from PL
Figure 9: Twisted Pair Wiring
EF-1 INTERFACE
4-1
• Warning: Never
look directly into the
fiber-optic light port
or into a connected
cable with the unit
powered up.
Simply connect the four-wire audio and four-wire data between EF-1 units utilizing this
cable. This will form a direct connection between the DB-15 connectors on a pair of
EF-1 units. The PL systems at each end of the cable will require their own power and
termination for their local channel.
Up to 5000 ft. (1.52 km) of CAT 3 or better cable, and possibly more, may be used to
connect between EF-1 units in this manner.
FIBER-OPTIC
Fiber optic transmission offers a number of advantages over copper:
• There is no susceptibility to electromagnetic interference.
• Fiber-optic cable is much lighter and more space efficient than copper, even for a single
channel.
• Fiber-optic converters
are available in many
models.
4-2
• Transmission distance, in many cases, can be substantially longer.
• It is more difficult to eavesdrop on a fiber transmission.
WARNING: Always use extreme caution with fiber-optic equipment. Never look directly
into the light port or into a connected cable with a unit powered up. Even if you don’t see
visible light, you could be exposing your eyes to invisible light from an infrared laser. This
can cause damage to your vision. Always observe all manufacturer’s recommendations and
warnings.
EF-1 INTERFACE
There are two basic modes of fiber-optic transmission. In a multimode fiber, the light
travels through the fiber via multiple paths. In a single-mode fiber, the light travels in a
single path. Depending on the equipment, single or multiple channels of audio, video,
data, or a mix thereof can be multiplexed and carried in either one or both directions.
Figure 10 illustrates wiring connections to a popular type of multimode fiber-optic
modem over shielded-pair cable.
Fiber Options
249B-T/1B44
or
249B-R/1B44
J1B
J1A
Pin 1
J1A
- Data Out
6
+ Data Out
Ground
Shielded Wiring
EF-1
14
- RS-422 Receive
5
13
+ RS-422 Receive
4
12
RS-422 Receive Shield
Audio Shield
3
11
4-Wire Audio Input Shield
- Audio Out
2
10
- 4-Wire Audio Input to Party Line
+ Audio Out
1
9
+ 4-Wire Audio Input to Party Line
J1B
- Data In 6
6
- RS-422 Transmit
+ Data In
5
5
+ RS-422 Transmit
Ground
4
4
RS-422 Transmit Shield
Audio Shield
3
3
4-Wire Audio Output Shield
- Audio In
2
2
- 4-Wire Audio Output from PL
+ Audio In
1
1
+4-Wire Audio Output from PL
Figure 10: Shielded Wiring
EF-1 INTERFACE
4-3
Just as with analog cable, the longer the length, the more signal degradation occurs. Cable
splices and connectors also contribute to overall path loss. Performance is dependent on
the modem, the cable, and the wavelength used. Single-mode fibers can carry signals over
much longer lengths, though the equipment is more costly, in part due to the use of lasers
rather than LEDs as the light source.
• Transmission
methods include
direct connection,
fiber-optic, and
ISDN.
4-4
For dedicated use, Clear-Com has found that the FiberOptions 249B series (multimode,
single-channel) works well for most single channel applications. Range is up to 2.5 km
(1.55 miles) with negligible signal loss at 1 km (0.62 mile) or less.
OTHER METHODS
Any device that can accept four-wire audio and RS-422 data and convert them in either
direction could be considered ideal for use with EF-1 units. There are a number of
choices for fiber-optic “modems” that meet this criteria. Selection is much more limited
among computer networking devices and audio codecs typically used with ISDN.
EF-1 INTERFACE
5
MAINTENANCE
TROUBLESHOOTING TIPS
Listed below are symptoms, causes, and solutions for some of the more common problems that may occur.
AUDIO TROUBLESHOOTING TIPS
Symptom
Cause
Solution
Squealing feedback, levels
too high, distortion, call
signal stays on.
The local PL channel is not terminated.
Check termination switches on PL
equipment and set appropriately. (One
termination per channel).
Levels seem low even after
adjustment.
The local PL channel has multiple
terminations.
Check termination switches on PL
equipment and set appropriately.
EF-1 INTERFACE
5-1
Symptom
Cause
Solution
Echoes, hollow sound,
resonance.
Improper nulls and/or delays
introduced by digital signal processing,
A-to-D and D-to-A conversion and
other network-related processing.
Adjust the unit(s) for the best possible null.
This will help to minimize the effects.
1. Additional level adjustments may be
available on the modems.
1. Always begin a setup with these set to
their nominal levels.
2. Clear-Com/RTS jumper set wrong.
2. Reset jumper.
Excessive noise or poor
frequency response.
Various causes related to modems and
the network rather than to the
party-line equipment.
Know the performance parameters of the
transmission system.
Level adjustment controls
seem to work backwards.
DB-15 is not wired correctly.
Check and correct wiring.
Levels don’t match from
one end to the other.
5-2
Adjust the sidetone nulls on the party-line
stations and beltpacks.
EF-1 INTERFACE
DATA TROUBLESHOOTING TIPS
Symptom
Cause
Solution
Data LED is off even
though units are
connected at each end.
1. Problem in the wiring from the
DB-15 to the modem or problem with
the transmission medium.
2. Baud rate or other modem
requirements not compatible with
EF-1.
3. The EF-1 units are set to different
baud rates.
1. Adjust wiring.
EF-1 is receiving a "break" signal from
the RS-422. Typically a power loss on
the modem at the far end causes this.
Check modem power connections.
Data LED blinks rapidly.
EF-1 INTERFACE
2. Adjust EF-1 units to match.
3. Adjust EF-1 units to match.
5-3
Symptom
Cause
Solution
Call signal is locked on at
one end.
1. Local PL problem.
1.Check PL.
2. DB-15 is wired incorrectly at other
end. This will happen if an RTS-TW
channel is connected at one EF-1 and a
Clear-Com is connected at the other,
but the DB-15 on the RTS end has not
been wired properly.
2. Check wiring.
5-4
EF-1 INTERFACE
NULLING TROUBLESHOOTING TIPS
Symptom
Cause
Solution
No audio; green LED is
off.
EF-1 is not receiving power.
EF-1 units at both ends of the connection
must receive power from a local PL system.
Unsatisfactory null.
1. Unstable PL system due to excessive
cabling, a high number of stations,
transformers connected across the
intercom channel, or other PL
equipment issues such as termination.
1. Verify operational status of PL
equipment.
2. Too many nulls on channel.
2. Remove EF-1 units from the network. If
nulls on the remaining units improve, the
problem was too many EF-1 units. This
should not occur until approximately seven
or more units are sharing a channel.
However, as systems vary in size and
complexity, a user could experience
difficulty nulling as few as two EF-1 units,
each connected to a very large system.
EF-1 INTERFACE
5-5
BLOCK DIAGRAM
TW Power
Splitter
Power
Intercom
Line
Power
Hybrid Null
Receive
Send
4-Wire
Output
4-Wire
Input
Gain
Adj.
Gain
Adj.
20 kHz
Call
200 Hz
Null
C-C Call
Send &
Receive
Nulling
Earphone
20 kHz Call
Receive
Phone
Det.
Microprocessor
C-C / TW
Mode
Baud Rate
Select
Data
RS-422
Send
RS-422
Receive
Figure 7: Block Diagram
5-6
EF-1 INTERFACE
C25
R95
P2
Baud 1
C53
Q8
D8
Q6
19.2 kBaud
9.6 kBaud
4.8 kBaud
2.4 kBaud
Baud 2
Open
Open
Closed
Closed
Open
Open
Closed
C63
R39
Closed
R45
R61
C55
R52
C32
R34
IC3
R51
R3
C64
IC2
R29
R27
R26
C65
D9
Q9
D6
IC1
C54
R78
R65
C40
R46
C47
R41
R58
R62
C20
C35
C24 R49
C31
D11
R20
C19
C14
C16
C13
C48
IC9
C52
R6
J1
R10
ASSY #710540
C7
C12
C11
R13
Q5
C45
R80
R73
C46
C8
R14
R8
C9
CLEAR-COM
R22
C44
R33
Q7
D7
R30
R92
R94
Made in USA
IC4 C34
C60
IC7
R37
COPYRIGHT (C) 2000
D1
Rate
P4
Baud 2
R28
R31
C6
R85
Baud 1
P3
R44
C28
R64
C68
C21
R35
R47
R32
R4
C67
R87 R25
C23
R38
C62
R69 R63
C26
D1
0
1
R48
R90
R40 C22
R82
R86
R89
R36
R18
R91
R68
R23
R93
C36
R74
R24
C37
R76
R70
R59
C38
IC5
C41
R19
R79
R2
C30
Q4
R5
Q3
R9
P1
IC6
C56
C10
D4
IC8
R60
C27
R42
C33
C18
R17
R57
R11
C39
C29
R43
C66
R75
R56
R72
R71
R7
C15
R15
R50
R12
C51
R16
C42
C43
R81
R1
R2
R66
R67
R54
C61
T1
C50
C58
C49
R83
R88
R53
C17
R84
R55
R77
C57
EF-1 INTERFACE
C59
J3
COMPONENT LAYOUT
J2
Figure 8: Component Layout
5-7
BILL OF MATERIALS
EF-1 PCB
CAPACITORS
Value
Type
Volts
Tol.
Part#
Designator
1
.01
220
2700
4.7
22
39
47
100
150
220
470
820
.0047
.01
.047
.1
uF
uF
uF
pF
uF
pF
pF
pF
pF
pF
pF
pF
pF
uF
uF
uF
uF
Aluminum NP
Ceramic Disc
Aluminum
2700PF PLY
Aluminum NP
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
Ceramic Disc SMD
50V
1.4KV
50V
50V
50V
50V
5OV
50V
50V
50V
50V
50V
50V
50V
50V
50V
50V
10%
20%
5%
5%
5%
5%
5%
5%
5%
5%
10%
10%
10%
10%
150002
150029
150037
150086
150087
151116
151119
151120
151124
151126
151128
151132
151135
151156
151160
151168
151172
.22
.33
.47
uF
uF
uF
Ceramic Disc SMD
Ceramic Disc SMD
Tantalum SMD
50V
25V
35V
10%
10%
10%
151176
151178
151184
C35
C61
C48 C52
C14
C31
C36
C39
C21 C22 C43 C63
C32 C62
C34
C15 C40 C64-C67
C9 C24 C26
C7 C33 C45
C8 C10 C29
C19 C23 C30 C42 C47
C12 C27 C37
C11 C13 C17 C18 C20
C68
C38 C44 C46
C25 C28
C6 C16 C50 C54 C55
5-8
2.5%
EF-1 INTERFACE
10
22
uF
uF
Tantalum SMD
Aluminum SMD
25V
50V
RESISTORS AND RESISTOR PACKS
Value
Power Type
10
4.7K
330
10
0
22.1
56.2
100
150
332
432
475
604
1.00K
1.50K
2.21K
3.32K
4.32K
4.75K
5.62K
6.81K
10.0K
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
1/4
1/4
1/4
1/2
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
EF-1 INTERFACE
Carbon Film
Carbon Film
Carbon Film
Carbon Film
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
10%
20%
151192
151200
C56 C57
C49 C51 C53 C59
C60 C58
Tol.
Part#
Designator
5%
5%
5%
5%
410002
410013
410061
410066
411100
411230
411269
411293
411310
411343
411354
411358
411368
411389
411406
411422
411439
411450
411454
411461
411469
411485
R88
R4
R2
R1
R79
R7
R12
R10
R77 R83 R91 R92 R93 R94
R24 R17
R49
R69 R72
R95
R16 R5
R20 R42 R50 R59
R61 R84
R70 R54
R53
R8 R14 R19 R30 R87
R60
R64
R6 R21 R22 R28 R29
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
5-9
14.3K
15.0K
19.1K
20.0K
22.1K
27.4K
33.2K
47.5K
OHM
OHM
OHM
OHM
OHM
OHM
OHM
OHM
1/10
1/10
1/10
1/10
1/10
1/10
1/10
1/10
SMD
SMD
SMD
SMD
SMD
SMD
SMD
SMD
1%
1%
1%
1%
1%
1%
1%
1%
411500
411502
411512
411514
411518
411527
411535
411550
56.2K
100K
OHM
OHM
1/10
1/10
SMD
SMD
1%
1%
411557
411581
221K
475K
562K
OHM
OHM
OHM
1/10
1/10
1/10
SMD
SMD
SMD
1%
1%
1%
411614
411646
411653
R81
R85 R68
R11
R46 R41
R52 R74
R51
R34 R37 R73 R80 R89
R15 R25 R36 R40
R56 R58 R65 R66
R67 R82 R86
R57
R18 R23 R27 R31
R32 R33 R35 R39
R44 R47 R48
R3 R26 R43 R76
R9 R62 R63 R90
R38
DIODES AND TRANSISTORS
Device
Description
Part#
Designator
Transistor
IC
IC
Diode
Diode
IC
Transistor
Transistor
480051
480083
480231
481019
481020
481023
481026
481027
Q5
IC8
IC1
D1 D8
D4
IC3 IC4 IC5 IC6
Q4 Q6 Q9
Q3
5-10
TIP30B PNP 80V 1A TO-220 PKG
7805T POS 5V REGULATOR
488E RS-422 XCVR
BAV70 DUAL DIODE
BAW56 DUAL DIODE
833 DUAL OPAMP... SMD
2222A NPN 40V 600MA... SMD
2907A PNP 60V 600MA... SMD
EF-1 INTERFACE
Diode
Transistor
IC
Diode
Transistor
IC
Transformer
IC
BAV99 DUAL DIODE... SMD
MPSA14 DNPN 30V 300MA... SMD
DG444 QUAD
ANALOG SW
5.1V 5% ZENER 1/4W... SMD
MPSA64 DPNP 30V 500MA SMD
567 PLL SMD
600CT/600CT
ASSY, EF-1 FIRMWARE
MISCELLANEOUS
Device
Description
Pot
LED
Pot
Pot
481033
481038
481050
D7 D9 D10
Q8
IC7
481061
481075
481081
560018
710541
D6
Q7
IC
T1
IC2
Part#
Designator
JUMP JACK.1IN WITH HANDLE
SHAFT FOR PT-10,
210226
240103
T1 RT ANG PC MTG
GREEN/YELLOW
50K TRIMPOT PIHER#PT10WH-50K
390063
5K TRIMPOT
EF-1 INTERFACE
R13 R45 R55 R71
R75 R78
D11
470059
R45 R55 R71 R75
470063
R78
R13
5-11
6 GLOSSARY
Category 3 (Cat 3) or Category 5 (Cat 5): EIA/TIA 568 category specification
relating to the performance of network cabling. Both are adequate for EF-1 wiring.
CODEC: a device that enCODes and DECodes data.
• The glossary gives
definitions of
technical terms
found throughout this
manual.
Drop(s): a point or points in the party-line system where a beltpack or station is present.
For purposes of this discussion, any point on a common channel where an EF-1 or other
four-wire to two-wire interface is present.
Four-wire audio: a single shielded-pair or twisted-pair cable carries audio in one
direction only.
Hybrid: a circuit that converts between four-wire audio and two-wire audio and contains
a nulling circuit.
Local PL: the party-line system connected to an EF-1 through a standard mic cable.
Also powers the EF-1.
6-1
EF-1 INTERFACE
Metric Conversions: The following table gives common metric conversions.
U.S. to Metric Measurement
1 inch = 2.54 centimeters
1 foot = 0.30 meter
1 mile = 1.6 kilometers (1.6093 kilometers)
Metric to U.S. Measurement
1centimeter = 0.39 inch (0.3937 inch)
1 meter = 3.3 feet (3.2808 feet)
1 kilometer = 0.62 miles (0.62137 miles)
Modem: MODulator/DEModulator. A device for converting an analog signal to/from a
digital or optical signal for transmission and distribution over various media and
networks.
Null or Nulling: cancellation of the audio returning to the source from which it
originated (see: Sidetone).
PL: party line.
RS-422: a balanced asynchronous data connection.
Sidetone: the level of one’s own voice in one’s headset or speaker.
Termination: a fixed load placed upon the Clear-Com party line to maintain stability.
Two-wire audio: a single shielded-pair cable carries a single (or two) channel(s) of audio
in both directions simultaneously.
TW: two channels of bidirectional audio are carried on a single shielded-pair cable.
EF-1 INTERFACE
6-2
7 SPECIFICATIONS
Call Signal (Clear-Com Mode)
Input Threshold:
Output Level:
4 Volts DC on audio line
11 Volts minimum on audio line
Call Signal (RTS Mode)
0 dBv is referenced to 0.775 V RMS
Input/Output:
Party Line Characteristics (Clear-Com Mode)
Nulling Capability
Frequency Response:
Audio Level:
Clipping Level:
Impedance:
200-10 kHz ± 3 dB
-15 dBv nominal
+3 dBv minimum
Greater than 10k Ohms (bridging)
Party Line Characteristics (RTS Mode)
Frequency Response:
Audio Level:
Clipping Level:
Impedance:
7-1
200-10 kHz ± 3dB
-10 dBv nominal
+3 dBv minimum
Greater than 10k Ohms (bridging)
Depth of Null:
Line Length:
Line Impedance:
Distortion:
20 kHz
>30 dB, 200 Hz–8 kHz
2 ft.– 4,000 ft. (1.64 m–1,220 m)
120 Ohms–350 Ohms
0.5% THD
Four Wire Audio
Transmit Level:
Impedance:
Receive Level:
Impedance:
Range:
Adjustable -15dBV to + 4dBV
600 Ohms, transformer isolated and
balanced
Adjustable -15 dBV to + 4 dBV
10k Ohms, electronically balanced
Up to 5,000 ft. (152 m)
EF-1 INTERFACE
Data:
Baud rate:
Settings:
Dimensions
19.2 kilobits per second, selectable for
2400, 4800, or 9600 baud
8 data bits; 1 stop bit; no parity
Height:
Width:
Depth:
Weight:
1.62 in. (41 mm) (1 RU, EIA rack)
5.94 in. (151 mm)
4.80 in. (122 mm)
1.75 lbs. (.794 kgs)
Test Tone
200 Hz Sawtooth Wave
Accessories
Connectors
Wiring diagram, adhesive backed
TS-1 testing earphone
(1) XLR male
(1) XLR female
(1) DB-15 1/8 in. (3.17 mm)
(1) phone jack on front panel
Power
DC Voltage:
24-32 VDC powered by intercom line
DC Current Requirement (with Data):
60 mA
DC Current Requirement (without Data): 40 mA
EF-1 INTERFACE
7-2
8 CLEAR-COM LIMITED WARRANTY
• Return authorization
numbers are
required for all
returns.
The Clear-Com Intercom Systems warranty does not cover any defect, malfunction, or
failure caused beyond the control of Clear-Com, including unreasonable or negligent
operation, abuse, accident, failure to follow instructions in the manual, defective or
improperly associated equipment, attempts at modification and repair not authorized by
Clear-Com, and shipping damage. Products with their serial numbers removed or defaced
are not covered by this warranty.
This warranty is the sole and exclusive express warranty given with respect to Clear-Com
products. It is the responsibility of the user to determine before purchase that this product
is suitable for the user's intended purpose.
Any and all implied warranties, including the implied warranty of merchantability, are
limited to the duration of this express limited warranty. Neither Clear-Com nor the dealer
who sells Clear-Com products is liable for incidental or consequential damages of any
kind.
8-1
EF-1 INTERFACE
For your own records fill in the information below:
Model No._________________________ Serial No.__________________________
Date Purchased _______________________________________________________
Purchased from (dealer)_________________________________________________
Address _____________________________________________________________
City ________________________________State _____ZIP ___________________
FACTORY SERVICE
• Warranty and
non-warranty repairs
are available.
Contact the factory.
Do not return any equipment to the factory without first obtaining a return authorization
number.
All equipment returned for repair must be accompanied by documentation stating the
return address, telephone number, date of purchase, and a description of the problem.
Send equipment to be repaired to:
Customer Service Department
Clear-Com Intercom Systems
4065 Hollis Street
Emeryville, CA 94608-3505
Telephone: (510) 496-6666
Fax: (510)496-6610
Web site: www.clearcom.com
EF-1 INTERFACE
8-2
WARRANTY REPAIR
If in warranty, no charge will be made for the repairs. Equipment being returned for
warranty repair must be sent prepaid and will be returned prepaid.
NON-WARRANTY REPAIR
Equipment that is not under warranty must be sent prepaid to Clear-Com. If requested,
an estimate of repair costs will be issued prior to service. Once repair is approved and
repair of equipment is completed, the equipment will be shipped freight collect from the
factory.
8-3
EF-1 INTERFACE
NOTES
NOTES