NEC TTS 26B User manual

l NSTRUCTION MANUAL
FOR
MODEL TTS 26 B
PULSE SIGNALING TEST SET
ISSUE 2
NORTHEAST ELECTRONICS CORPORATION
P. 0. BOX 649 - CONCORD, N. H. 03301

PROPRIETARY NOTICE
The information contained in this publication is the
of Northeast Electronics Corporation and may not be reproduced
or used for manufacturing purposes or disclosed to third parties
without the written permission of Northeast Electronics Corpor-
ation.
WARRANTY
NEC warrants all products manufactured or sold by NEC to
be free from defects in materials and workmanship, subject to
the following terms and provisions.
NECts obligations under this warranty are limited to repair-.
ing, adjusting, or replacing at our option, with reasonable prompt-
ness, any NEC product which shall
within twelve (12) months after
delivery to the original purchaser, and after normal and proper us
-
age, prove to be defective on NEC inspection, provided that the
purchaser shall have reasonably inspected products when received
and notified NEC of any apparent defects discovered
within fifteen
(15) days of receipt of shipment. NEC shall not be liable for any
manufacturing costs of the buyer, lost profits or good
will of the
buyer, or any other special or consequential damages sustained
or expenses incurred
by the buyer by reason of the ilse or sale
of any defective NEC product.
No products may be returned to NEC except
with our written
permission. After receiving NEC factory authorization, material
requiring repair
or replacement should be sent prepaid to the fac-
tory accompanied by a written statement setting forth as comphte-
ly ae possible the defects and the conditions under which they occur-
red. Material delivered by NEC shall not be considered defective
if it satisfactorily Wills the buyer's performance requirements
and/or is in accordance wi%-approvedsamples. NEC8sobligations
on performance of products delivered shall be limited to comply-
ing with specifications accompanying a purchase order or dth pub-
lished epecifications on standard catalog items. This warranty does
not extend
to any NEC products which have been subject to misuse,
neglect, accidents or improper installation or applications, nor
shall it extend to units which have been repaired or substantially
altered outside the NEC factory, nor to any associated instruments
,
equipment6 or apparatus. This warranty is in lieu of all other war-
ranties, express or implied.

TTS 26B
Section
1
2
3
4
5
6
Figure
3-1
3
-2
3-3
3-3a
3-3b
3-3c
TABLE OF CONTENTS
Title
GENERAL DESCRIPTION
SPECIFICATIONS
OPERATING INSTRUCTIONS
CIRCUIT DESCRIPTION
MAINTENANCE
ELECTRONIC PARTS LIST
LIST OF ILLUSTRATIONS
Title
Front Panel Controls
Send Circuits
Receive Circuits
Meter Circuit
Meter Circuit
Meter Circuit
Supervisor Monitor Circuits
TTS 26B Block Diagram
TTS 26B Schematic Diagram
Component Location
E95075
Component Location E95026
Page
1 - 1
2-1
3-1
4- 1
5-1
6-1
Page
2 -2
3-8
3
- 10
3-12
3
- 16
3-18
3-23

TTS 26B
SECTION 1
Section 1
1.1
GENERAL.
1.2 The Model
TTS 26B is a compact pulse sig-
naling test set designed to send pulses generated
by either a built-in. transistorized oscillator or an
external source, and to measure the
'36 break and
speed of the transmitted pulses, or of pulses
received from external sources. The
70 break of
the pulses transmitted by the instrument can be
varied over a wide range. The speed of these
pulses can be varied in seven discrete steps.
1.
3
Signals can be received or transmitted on a
loopor an
E&M basis. A seriesof jacks isprovided
for the proper connection to the particular circuit
to be tested. Switches and keys permit the test-
man to set up testing circuits for different combin-
ations of sending and receiving on the basis of
loop,
E&M, or a combination of both signaling
sys
terns.
1.4 The Model TTS 26B may be used as a pulse
repeater or converter. Signals from
an external
circuit may be applied to the EXT
DIAL jack or
terminals and used to operate the internal pulsing
relay. The
OJo break of this output signal can be
varied, and it can be retransmitted on a loop or
an %&M basis. It can be used to control external
circuits such as voice-frequency signaling circuits,
polar duplex circuits, etc.
1.
5 Measurements may be made by connecting
the high impedance meter circuit to the circuit
under test either directly or through a low imped-
ance "slave" relay. The meter slave relay
is
particularly useful when testing circuits which
have high capacitance or inductance. Such circuits
might distort the pulse wave shape and thereby
result in erroneous meter readings if the high
impedance meter were used directly on the cir
-
cuit under test.
1.6 The meter has
two scales - one for measur-
ing
OJo break and the other for pulse speed mea-
surements in pulses per second
(PPS).
The
correct scale is obtained
by switching the meter
circuit to correspond to the selected mode of
operation.
1.7 The TTS
26B may be operated from the
48-volt central office battery or from
a suitable
substitute such
as an NEC PSI01 - In emergen-
cies a heavy duty 45-volt dry cell will supply
adequate power to the instrument for a shorttime.
1. 8 The set is contained in an aluminum carrying
case with a removable, hinged cover which inclu-
des
a storage compartment for cords, small
tools, and such items.
1.9 Accessory covers are available to provide
additional functions which increase the versatility
of the Model TTS
26B. These can be substituted
for, or ordered in place of, the removable cover
which normally
is supplied with the set.
A
separate description of each of the cover acces-
sories is supplied as supplementary information.
1.
10 A relay rack mounted version of the TTS 26B
is available in the form of the TTS 26BDR.

TTS 26B
SECTION
2
SPECIFICATIONS
2.1 GENERAL.
Section
2
2. 2 Table 2- 1 Lists the specifications of the TTS 26B
TABLE
2-1
METER
Ranges
70 Break: 070 to 100'70
Speed: 0 to 25 pps
Scales
O/o Break: 170divisions
Speed
: 1 pps divisions
. -
IMPEDANCE OF MEASURING CIRCUITS
Meter Circuit: Approx. 7,50052
Meter Relay: Approx. 40052
FOR SPEED MEASUREMENTS
Approx. 4,30052
SEND SIGNALS
- Internal Oscillator: 4,6,8,10,12,
14,20 ~ulses/~ec.One addi-
tional frequency can
be installed
on special order.
External Dial:
A standarddialor20pps
dial may be used to generate
pulses
.
'% Break Range: At least 12%to 8570
Transit time <1 millisec.
CONTROLS
ADJ
yo BREAK
METER CAL
METER CIRCUIT Switch
FUNCTION Switch
PULSES PER SEC Switch
RECEIVE Switch
SEND Switch
EXT DIAL CIRCUIT Switch
SEND and TEST Key Switch
TWD-L Key Switch
TWD-D Key Switch
SEND Turnbutton Switch
SPARK
SUP Turnbutton Switch
DROP
E =G&O M -B&O
DROP E =G&B M =B&O
Toggle Switch
JACKS
1. EXT DIAL
2. SEND RELAY
3. SEND 1 (LOOP)
4. SEND
2 (LOOP)
5. SEND B&G
6. REG LOOP
7. REC E&M
8. E
9. M
10. LINE
11. DROP
12. 48VoltS(-) T(+)
13. 48 Volt S (t) T (-)
14. EXT ADAPT (FOR ACCESSORIES)
15. DROP
E =G&O M =B&O
DROP E =G&B M =B&O
SUPERVISORY LAMPS
LINE (E)
DROP
(M)
POWER REQUIREMENTS
48 volts
DC, 220mA
Operable from approx. 40V to 55V
Diode protection for polarity reversal.
24 volt DC operation available on
special order.
SIZE
14"w x 10"h x 8"d (includes cover)
WEIGHT
1 5 pounds
RACK MOUNTED EQUIPMENT
The Model TTS 26B is also available
for bay mounting; it is called Model
TTS 26BDR. It includes a telephone
dial as well as all the features of the
portable set.
Any of the accessories available
for the cover of the TTS 26B can be
supplied on panels for bay mounting.
Ordering information will be supplied
on request.

TTS 26B
Section 2
Figure 3-1. Front Panel Controls

TTS 26B Section
3
SECTION 3
OPERATING INSTRUCTIONS
- 3.1 GENERAL.
--
3.2
Table 3-1 lists the functions of all controls and indicators shown indexed on fig. 3-1.
Paragraphs
3.3 through 3. 19 provide the operating instructions.
TABLE 3-1
Index No. Control or
Indicator Function
SEND PPS Switch
- Provides the following functions:
1. Switches the power on or off.
2. Controls the pulse rate of the internal oscillator for
any one of the available seven discrete pulse rates.
ADJ
70 BREAK Provides the means for adjusting the
70 break of the
POTENTIOMETER transmitted pulses from the internal oscillator or from
an external dial.
METER CAL Provides the means for calibrating the meter circuitry.
POTENTIOMETER
FUNCTION SWITCH Provides the following functions in clockwise sequence:
1. SEND a. ON HOOK
b. OFF HOOK
2. SEND AND
REC
L
I
'8
3. CAL a. ADJ 170 BREAK
\
b. CAL METER
RECEIVE Switch Provides the following receive functions in clockwise
sequence:
1. B&G ON LOOP
2. LOOP
3. B&O (M)
5. G&O(E)
6.
The final clockwise position permits the SEND or SENE
AND REC switch to control both sending and receiving
functions, as shown in item
6 following.

Section 3
TTS 26B
TABLE 3-1
Index No. Control or Function
SEND or SEND AND Provides the following,sending modes in clockwise sequence,
RECEIVE switch when the receive switch is in final clockwise position:
1. SEND LOOP, REC G&B .
2. SEND LOOP, REC LOOP
3. E&M LINE B &G on M
DROP G&Oon E
4. E&M LINE B&Oon M (See Note 1)
NOTE 1: The
E lead status in this mode is controlled by
the DROP toggle switch.
NOTE: The two SEND LOOP positions provide identical
sending conditions; only the receiving functions
are different in these positfons when this switch
.
is used to control both sending and receiving
functions.
METER CIRCUIT Provides the following measuring functions inclockwise
switch sequence:
1. 0-25 PPS (Pulse Speed)
2. 70 BREAK DIRECT
3. 70 BREAK T-HRUMETER RELAY
EXT DIAL CIRCUIT Provides the following modes of operation of the external
switch dial circuit in clockwise sequence:
1. TALK
2. DIAL RELAY B&G
3. DIAL RELAY a. LOOP
b. M
c. E
FUNCTION key switch Provides the following functions:
1. TEST L&D(operated upward) This position disconnects
the LINE and DROP, and the
E and M jacks from access to
other circuits of the set. The LINE (E) and DROP (M) lamp
relays are bridged on, and the LINE and DROP jacks are
connected together tip to tip and ring.to ring.
2. SEND DIAL (position normal)
3. SEND OSC (operated downward)

TTS 26B
Section 3
TABLE 3-1
Index No. Control or Function
Indicator
10 LINE
(E) key switch Provides for the connection of the following supervisory
and measurement functions toward the line:
1. ON HOOK (operatedupward)
2. MONITOR (norma1 position)
3. OFF HOOK (operated downward)
DROP (M)key switch Provides for the connection of the following supervisory
and measurement functions toward the line:
1. ON HOOK (operatedupward)
2. MONITOR (nor
ma1 position)
3. OFF HOOK (operated downward)
SEND turnbutton switch Provides the following SENDfunctions on the LOOP SIGNAL-
ING jacks SEND 1 and SEND
2:
1. SEND RT ON 1&2(operated clockwise)
2.
SEND SLEEVES (operated counter clockwise)
In normal use this switch should be in the SEND RT
ON 1&2
position. The pricipal use for the SEND SLEEVE position
is for special applications where direct access to the SEN1
relay armature, make, and break contacts is desired
SPARK
SUP turnbutton Inserts an internal spark suppression circuit across the
switch SEND RELAY CONTACTS.
DROP toggle switch Determines the sending status of the
E lead, either ground
and open or ground and battery.
Jacks The following 310-type jacks are provided from left to right:
1.
EXT DIAL (for connecting an external dial, pulsing
source, or a telephone set)
2. SEND RELAY (fordirectconnectionto the relaycontacts)
3. LOOP SIGNALING
- SEND 1
4. LOOP SIGNALING - SEND 2
5. LOOP SIGNALING - SEND B&G
6. LOOP SIGNALING - REC LOOP
7.
EAND M SIGNALING - REC E&M
r

TTS 26B
Section 3
TABLE 3-1
Index No. Control or Function
Indicator
15 (cont) Jacks
TERMINALS
LAMPS
18 METER
8.
E AND M SIGNALING - E (for connection to the E lead)
9.
E AND M SIGNALING - M (for connection to the M lead)
10. E AND M SIGNALING - LINE
11. E
AND M SIGNALING - DROP
12- 48 VOLT, S =BATT, T =GND
The following terminals are provided:
1. EXT ADAPT Connector
- Provides for connection to
accessory covers (Located in upper left of panel).
2.
EXT DIAL Binding Posts (2) - Provides for connection
of an external dial, source of pulses, or of a telephone
set (located in upper left of panel).
3.
GND Binding Posts - Provides access to the TTS 26B
ground.
Two supervisory lamps, designated
LINE (E) and DROP (M)
are provided to indicate a busy (lampdark) or
idle condition
(lamps lighted) an the line and drop circuits to which the
'
set is connected, when E and M supervision is present on
the circuits.
Provides a display for all measurements.

TTS 26B Section 3
3. 3 The different circuits which can be set up
under the control of the RECEIVE, and the SEND
or SEND AND REC switches are shown in simpli-
fied form in figs. 3-2, 3-3 and 3-4. These illus-
trate the circuits connected to the various jacks
for different positions of these switches when the
FUNCTION switch is in the SEND AND REC posi-
tion. These diagrams serve as
a quick reference
to determine what test connections are being used.
3.4 When the cover of the set has been unlatched
and opened it can e3sily be detached by sliding it
to the right. If cords or other items stored in the
cover are needed the hinged lid within the cover
may be opened by first turning the thumbscrew
which serves as the latch.
3.5 CORDS
3.6 Power supply cord
- This cord should provide
tip and sleeveconnections fromthe setto
48 volts dc
(40to
55 volts). It should have a 310-type plug on the
end toward the set. It shouldbe insertedintothe set
FIRST
, and thenconnected to the power sourcein
order to avoid blowing afusewhenconnectionis
made to the set. For the samereasonit shouldbe
disconnected fromthe power sourceFIRST before
itisremoved fromthe set. Power maybe obtained
fromthe centraloffice battery orfrom
aNECPSI01
power supplyunit or equivalent.
3.
7 Sending and receiving test cords - Two -
conductor cords (tip and ring) are sufficient for
dl tests except those special tests requiring
direct access to the contacts of the SEND relay,
and tests involving sending on the sleeves. For
these special tests a 3-conductor cord (tip,ring
and sleeve) is needed. All cords should be equip-
ped with a 310-type plug on the end toward the
signaling test set.
3.8 Monitoring and Supervisory Lamps. The tip
of the E AND
M SIGNALING LINE jack in the set
is connected to the tip of the DROP jack, and
similarly the ring of the LINE jack to the ring of
the DROP jack. Hence, when the line and drop
jacks of
a trunk, on the line side of E and M sig-
naling equipment, are patched to these, the con-
tinuity of the trunk is completed through the set.
However, it should .be noted that during the patch-
ing operation an interruption in the continuity of
the trunk is caused. This would result in-
1 hit
that would be detrimental to any data being trans-
mitted over the trunk, no matter how rapidly the
patching oper
ations are made.
3. 9 After completion of this patching, when the
FUNCTION key is in the TEST L&Dposition and
the LINE
(E) and DROP (M) keys are normal (at
MONITOR), relays bridging on the tip and ring
con.trol the LINE (E)and DROP (M) lamps to
indicate whether or not an idle or busy trunk is
connected through the LINE and DROP jacks. Thus
these lamps will be lighted to indicate idle trunk
conditions, or dark to indicate busy conditions.
3. 10
A bridging test of O/o break may be made on
an E or
M lead. The FUNCTION switch is turned
to SEND AND REC, the METER CIRCUIT switch to
70 BREAK DIRECT (do not use the low impedance
THRU METER RLY position), the TEST SEND key
is restored to SEND DIAL, and the RECEIVE switch
is turned to the appropriate E or
M position.
When the appropriate E and M SIGNALING
- E or
M jack in the set is used, and if the trunk under
test
is in service it is important that the patch to
its E or
M lead should be bridged only (i.e. should
not open the E or
M lead of the trunk).
3. 11 A further application of this meter monitor
-
ing discussed in the preceding paragraph permits
an observation of the received 70 break to be made
on the
E or M lead while the set is sending on the
other of these leads. For this use theFUNCTION
key must be in either the SEND DIAL or the SEND
OSC position, with the switches involved in send-
ing set at their required positions.
3.12 SENDING SIGNALS WITH A PREDETERMINED
% BREAK.
3. 13 Fig. 3-3,3-3a,3-3b show in simplified
schematic form the circuit for sending in each of
the sendingpositions of the SEND ok SEND AND
REC switch.
3.14 CALIBRATION FOR SENDING
Oj6 BREAK
PULSES. The meter of the TTS 26B must be cali-
---
brated for the supply voltage used. When properly
calibrated
, the set will operate satisfactorily
from a stable voltage supply, and the METER CAL
control permits calibration of the meter if the
supply voltage does not lie outside limits extending
from 40 volts to
55 volts.

TTS 26B
Section
3
3.15 SENDING LOOP SIGNALS. The following provides the Procedure for Sending Loop Signals on
a
Loop Circuit (See fig. 3-3a):
ACTION RESULT
a. With no power applied to the set, check the It should be on the
100 line of the % break scale
position of the meter pointer. (meter electrical
0).
If it is off adjust the screw
on the front of the meter case to bring it to this
line.
b. After adjustment, back off the adjustment
screw slightly to remove mechanic
dl contact
between the adjustment screw and the meter
mechanism.
c. FIRST insert the 310-type plug of the power
supply patch cord into the 48 VOLT jack of the set
observing that the proper tip and sleeve polarity,
and then connect it to the 48-volt dc supply.
d. Turn the SEND
PPS switch to the desired
pulse rate
if the internal oscillator is to be used
as the source of signals.
If a dial or other exter -
nal source is to be used turn the switch to any
position except
PWR OFF.
e. If the LINE (E)and DROP
(M) lamps do not
light remove the dc power supply first, then
change the 310-type plug to the other 48 VOLT
jack, and reconnect the 48-volt dc power supply.
f.
If the internal oscillator is to be used as the
source of pulses, operate the FUNCTION key to
SEND OSC. If
a dial or other external source or
pulses is to be used, restore the FUNCTION key
to the SEND
DIAL, turn the EXT DIAL CIRCUIT
to
DIAL RLY -B&G, and connect the externaldial
or other source of pulsing to the EXT
DIAL jack
or terminals.
g. Turn the FUNCTION switch to CAL METER.
h. Turn the FUNCTION switch to CAL VoBREAK.
i. Turn the FUNCTION switch to SEND AND REC.
CAUTION
When the
TTS 26B is used to pulse
repeaters, carrier pulsing units, etc.
,
care should be exercised to simulate
the pulsing source in the system under
test. In many cases the pulsing source
This completes the mechanic
a1 adjustment' of
the meter electrical
0.
If connection is not made in this sequence a
battery supply fuse may blow. If the wrong
48-volt jack
is used diode protection within the
setwill protect the set from damage, but the
set will be inoperative in succeeding steps.
This turns the set on. The LINE (E)
and DROP
(M) lamps should light. If they do light proceed
to step
f. If they do not light proceed to step e.
The lamps should light.
If they still do not, the
set is probably not receiving power.
The internal oscillator pulses at the rate deter-
mined in step d. If
a dial or other external
sour.ce is to be used a series of zeros must be
dialed during the calibration procedure.
Adjust the METER
CAL control to obtain 0 on
the
70 BREAK scale of the meter.
Adjust the
ADJ 70 BREAK control to the desired
% break as indicated on the meter. If the dial
is used to generate the signal, dial a series of
zeros when adjusting
70 break.
The set is now ready to send pulses at the
required speed and
70 break. Except for the
SEND or SEND AND REC switch, the positions
of other-switches and keys in the set are imma-
terial.
If the pulse speed is changed the $ break
calibration should check. The procedure up to
this point applies to sending dry pulses on
a wet
loop, or wet pulses on
a dry loop. To send dry
pulses on a wet loop proceed with the remaining
S~DS of this ~ara~ra~h and fnllnw Nfib~ 1

ACTION
TTS
26B
Section 3
RESULT
will have a spark suppression circuit
across the pulsing contacts. Under these
conditions,
if the spark suppression in the
TTS
26B is not used erroneous results will
be obtained. If required, turn the
SPARK
SUP turnbutton to ON, otherwise use it in
the
OFF position .
j. Turn the SEND or SEND AND REC switch to
either of the SEND LOOP positions. If the SEND
LOOP-REC LOOP is used the turnbutton switch
in the lower left corner MUST be turned to SEND
RT
ON 1&2(its normal position).
k. It is assumed that the loop circuit involved
has been turned down to traffic. If-it
is necessary
to dial and talk on the circuit over which pulses
are to be sent, connect a telephone setwith
a
dial to the EXT DIAL jack (or terminals) tip and
ring with a 310-type plug on the cord.
1.
Turn the EXT DIAL CIRCUIT switch to DIAL
RLY - B&G.
m. Restore the FUNCTION key to
SEND DIAL.
n. Patch the circuit on which dial pulses are to
be transmitted to either of the LOOP SIGNALING-
SEND 1 or
2 jacks with a 2-or3-conductor cord
having a
3 10- type plug on the end toward the set,
using tip and ring conductors.
0.
After dialing on the circuit, it is possible to
listen to the ringing and to talk on the circuit by
turning the EXT DIA-L CIRCUIT switch to TALK
EM.
p.
When the circuit is prepared to receive dry
contact pulses they may be sent on the circuit
from the internal oscillator by operating the
FUNCTION key to SEND OSC. To send with the
dial of the telephone set or with the dial connected
to the EXT DIAL jack or terminals, restore the
FUNCTION key to SEND DIAL and turn the
EXT
DIAL CIRCUIT switch to DIAL RELAY - B &G.
This also applies to a dry contact external source
connected to the EXT DIAL jack or terminals.
If the external source supplieswet contact pulses,
the EXT DIAL CIRCUIT switch should
be turned
to DIAL RELAY-LOOP.
steps of this paragraph. If it is desired to send
battery and ground, or battery and open on
a
dry loop, such as into the dry winding of a relay,
omit the remaining steps of this paragraph and
follow Note
1.
It is immaterial which SEND or SEND AND REC
position is used unless conditions for receiving
measurements also must be controlled. The
type of receiving measurements would be con-
trolled if this switch is used to establish both
sending and receiving conditions.

TTS 26B
Section 3
SEm CUZCUfTs
Thesireuik rharn ba(arore Weetedbyttm
SEN0 OR SEM) AN0 REEM switch.
Contacts are shown in tha make or off
hook position.
SarO
LOOP
REC
UXR
NOTE; In Ms pdtiar d Wia switch
The E led stofaha fs aka
controlled by the DROP toggls switch
Figure 3-2 SEND CIRCUITS

TTS 26B Section 3
NOTE 1: To send battery and ground, or battery and open on
a dry loop, as into the drywinding of
a relay, the preceeding
is followed through step h. Then (the FUNCTION key being restored
to SEND DIAL and the external source being patched to the EXT DIAL jack or terminals)
the EXT DIAL CIRCUIT switch should be turned to DIAL RELAY-LOOP, and the SEND or
SEND AND REC switch to the E&M
- LINE (E =G&O, M =B&G)position for sending battery
and ground, or the E&M-LINE (E=G&O,M =B&O)position for sending battery and open.
The circuit over which the pulses are to be sent
is patched to the LOOP SIGNALING-SEND
B&G jack, tip and ring, with a 2- or 3-conductor cord having a 310-type plug on the end
toward the set.
3.16 SENDING ON THE E OR
M LEAD. The following provides the procedure for Sending Signals on
either the E lead or the
M lead.
ACTION RESULT
a. With no power applied to the set, check the It should be on the 100 line of the
70 BREAK scale
position of the meter pointer. (meter electrical 0). If it is off adjust the screw
on the front of the meter case to bring it to this
-
line.
b. After adjustment, back off the adjustment This completes the mechanical adjustment of
screw slightlyto remove mechanical contact the meter electrical 0.
between the adjustment screw and the meter
mechanism.
c. FIRST insert the 310-type plug of the power If connection is not made in this sequence
a
supply patch cord into the 48 VOLT jack of the set battery supply fuse may blow. If the wrong
48-
observing the proper tip and sleeve polarity, and volt jack is used diode protection within the set
then connect it to the 48-volt dc supply. will protect the set from damage, but the set
will be inoperative in succeeding steps
.
d. Turn the
SEND PPS switch to the desired This turns the set on. The LINE (E)and DROP
pulse rate if the internal oscillator
is to be used
(M) lamps should light. If they do light proceed
as the source of signals. If
a dial or other external to step f. If they do not light proceed with step e.
source is to be used, turn the switch to any
position except PWR OFF.
e. If the LINE (E)and DROP (M)lamps did not
light remove the dc power supply firsi,then
change the 310-type plug to the other
48 VOLT
jack and then reconnect the 48-volt dc power supply.
f. If the internal oscillator
is to be used as the
source of pulses, operate the FUNCTION key to
SEND OSC. If
a dial or other external source of
pulses is to be used, restore the FUNCTION key
to SEND DIAL. Turn the EXT DIAL switch to
DIAL RELAY-B&G, and connect the external dial
or other source of pulsing to the EXT DIAL jack
or terminals, tip and ring.
g.
Turn the FUNCTION switch to CAL METER.
h.
Turn the FUNCTION switch to CAL $% BREAK.
The lamps should light. If they still do not the
set probably
is not receiving power.
The internal oscillator pulses at the rate deter-
mined instepd. If adialorother externalsource
is
used, a series
of zeros must be dialed or the
external source must be operated during the
calibration procedure.
Adjust the METER CAL control to obtain 0 on
the
70 BREAK scale of the meter.
Adjust the
ADJ 70 BREAK control to the desired
70 break as indicated on the meter, If a dial is
used to generate the signal, dial a series of
zeros when adjusting to the desired
O/o break.

Section 3
The RECEIVE CIRCUITS hown at loft
or* selacted either by )ha first clockwise
positions of th. RECEIVE switch aby
tb SEND OR SEND 'WD RECEIVEswitch
when thr RECEIVE nltch is h itsfhl
Clockwise po8lt(On&
RECEIVE C IRCLJITS
SEND OR SEND AND
RECEIVEswltch
position.
0-25PPS 7HR.I METER RELAY
LOOP L
SEND OR SEND
AND RECEIVE
smnn
0-25 pps THRU METER RELAY
REC. LOOP
rC'" Lm
SEND OR SEND
AND RECEIVE
swm
RECEIVE SWITCH
V ' I
SNOORSEND
AND RECEIVE
Svrm
v-: in ttis posit-
the rtakuotnwEkod
is dro amtrolled Wthe
oRap Rlg* switch.
RECEIVE WITCH
d
RECEIVE Swm
d
SEND OR SEND
AM0 RECEIM
swnw4.
UNE
I4
d
RECEIVE SWlC?i
SENDORSEN0
AND RECEIVE
mn
d
SEND OR SEWD
AND RECEIVE
SWITCH.
Figure 3-3 RECEIVE CIRCUITS

TTS 26B
Section 3
ACTION RESULT
o. To send pulses from the internal oscillator
operate the FUNCTION key to SEND OSC.
To
send with the dial of a telephone set, or with a
dial connection to the
EXT DIAL jack or terminals
restore the FUNCTION key to SEND DIAL and
turn the
EXT DIAL CIRCUIT switch to DIAL
RELAY-
B&G.
This also applies to a dry contact
external source connected to the EXT DIAL jack
or terminals. If the external source supplies wet
contact pulses, the EXT DIAL CIRCUIT switch
should be turned to DIAL RELAY-LOOP. (See
Note
3).
NOTE 2: If it is desired to send ground and battery the SEND or SEND AND REC switch must be in
the extreme clockwise position and the
DROP toggle switch must be operated to DROP -
E =G&B.
NOTE 3: If the trunk test is patched through the LINE and DROP jacks of the TTS 26B and the set
is sending on the
M lead, the trunk may be made busy toward the dropby operating the
DROP
(M) key to OFF HOOK Similarly, sending on the
E lead the trunk may be made busy
toward the line by operating the LINE
(E) key to OFF HOOK. This
is shown in schematic
form infig.
3 -2.
3.17 MEASURING O/o BREAK OF A RECEIVED SIGNAL.
In all these measurements it is important to
----
adjust the METER CAL control to take into account the voltage drop across any resistance between the
source of the signals and
the measuring set. This
is accomplished while the METER CAL control is
being adjusted, by having a short circuit or off hook present at the source of signals. It also
is import-
ant that this adjustment should be made AFTER the receiving mode of the measuring set has been estab-
lished by the RECEIVE switch
( or the SEND or SEND AND REG switch if this switch controls the
receiving
as well as the sending modes). If another
TTS 26B is being used as the source of signals, the
off hook may be applied to the trunk by opening its
FUNCTION switch to SEND-OFF HOOK.
3.18 MEASURING
% BREAK ON LOOP CIRCUITS. The following provides the procedure for Measuring
% Break on Loop Circuits (See fig. 3-3a):
ACTION RESULT
a. With no power applied to the set, check the It should be on the 100 line of the
(70 BREAK
position of the meter pointer. scale (meter electrical
0). If it is off adjust the
screw on the front of the meter case to bring it
to this line.
b.
After adjustment, back off the adjustment
screw slightly to remove mechanical contact
between the adjustment screw and the meter
mechanism.
c.
FIRST insert the 310-type plug of the power
supply patch cord into the
48 VOLT jack of the
setobserving the proper tip and sleeve polarity,
and then connect it to
the 48-volt dc supply.
This completes the mechanical adjustment of the
meter electrical
0.
If connection is not made in this sequence a
battery supply fuse may blow.
If the wrong 48-
volt jack is used diode protectipn within the set
will protect the setfrom damage, but the set
will be inoperative in succeeding steps.

TTS 26B
Section
3
ACTION RESULT
d. Turn the SEND PPS switch to any position This turns the set on. The LINE (E) and DROP
except PWR
OFF. (M)lamps should light. If they do light proceed
to step
f. If they do not light proceed to step e.
e. If the lamps did not light remove the dcpower The lamps should light. If they still do not the
supply
fir st, then change the 31 0-type piug to the set probably is not receiving power.
other 480~~jack, and then reconnect the
48-
volt dc power supply.
f. For wet loop circuits turn the RECEIVE switch
to B&G ON LOOP, or
if this switch is used in
the fully clockwise position to transfer control to
the SEND or SEND AND REC switch, turn the
(latter)switch to SEND LOOP-REC
B&G. For dry
loop circuits turn the RECEIVE switch to REC
LOOP, or if this isused in the fully clockwise
position to transfer control to the SEND or SEND
- ANDRECswitch, turnthat(1atter)switchto
SEND LOOP-REC LOOP. If the set is being used
for simultaneous sending with this switch in the
SEND LOOP-REC LOOP position, the turnbutton
in the lower left corner of
the panel MUST be
turned to SEND RT ON
1&2.
g.
Turn the METER CIRCUIT switch to 70 BREAK If the circuit has high inductance or capacitance
DIRECT
. that may distort the pulse wave shape, the
METER CIRCUIT switch should be turned to
% BREAK THRU METER RELAY instead or
erroneous readings may be obtained.
h.
The FUNCTION, LINE (E) AND DROP (M)
keys should be normal unless required for simul-
taneous sending. The EXT DIAL CIRCUIT switch
is not in the measuring circuit. The
SPARK SUP.
turnbutton is not involved.
i.
It is assumed that the loop circuit involved
has been turned down to traffic. At the measuring
TTS 26B patch the circuit to the LOOP SIGNAL-
ING-REC LOOP jack, with a cord having
a 310
type plug on the end toward the set. If a wet loop
is involved the battery
(-) should be on the tip and
ground
(t) on the ring.
j. Request an off hook or short circuit at the
point where the signals are to
be applied.
k. Turn the FUNCTION switch to CAL METER. Adjust the METER CAL control to obtain 0 on
the
70 BREAK scale of the meter.
1.
Turn the FUNCTION switch to SEND AND-REC, Read the
70 BREAK on the 70 BREAK scale of the
and request the distant end to send the signal to meter of the set at the measuring end.
be measured instead of the off hook or short cir-
cuit.

TTS 26B
Section 3
3.19 MEASURINCI 70 BREAK ON THE M LEAD. The following provides for Measuring
Ole Break on an
M lead (See fig. 3-3b):
ACTION
a. With no power applied to the set, check the
position of the meter pointer.
b.
After adjustment back off the adjustment screw
slightly to remove mechanical contact between the
adjustment screw and the meter mechanism.
c. FIRST insert the 310-type plug of the power
supply patch cord into the 48 VOLT jack of the
set observing the proper tip and sleeve polarity,
and then connect it to the 48-volt dc supply.
d. Turn the SEND PPS switch to any position
except PWR OFF.
e.
If the lamps did not light remove the dc power
supply first, then change the 310-type plug to the
other
48 VOLT jack, and then reconnect the 48-
volt dc power supply.
f. To measure
7'0 break of battery and open pulses
on the
M lead turn the RECEIVE switch to
REC
B&O, (Id) or if this switch isused in the fully
clockwise position to transfer control to the
SEND
or SEND AND REC switch turn that (latter)
switch to
E&M - DROP, E =G&O, M =B&O. To
measure
'$0 break of battery and ground pulses
on the
M lead turn theRECEIVE switch to REG
B&G (M) or if this switch is used fully clockwise
to transfer control to the SEND or SEND ANDREC
switch turn the (latter)switch to E&M-DROP
E =G&O, M =B&G.
g.
Turn the METER CIRCUIT switch to O/o
BREAK DIRECT.
RESULT
It should be on the 100 line of the
70 BREAK scale
(meter electrical
0. )
If it is off adjust the screw
on the front of the meter case to bring it to
this line.
This completes the mechanical adjustment of
the meter electrical
0.
If connection is not made in this sequence a
battery supply fuse may blow. If the wrong 48-
volt jack is used diode prote-ction within the set
will protect the set from damage, but the set
will be inoperative in succeeding steps .
This turns the set on. The LINE
(E) and DROP
(M) lamps should light. If they do light proceed
to step
f.
If they do not light proceed to step e.
The light should light. If they still do not the
set probably is
not receiving power.
~f the circuit has high inductance or capacitance
which may distort the pulse wave shape the
METER CIRCUIT switch should be turned to
70 BREAK THRU METER RELAY or erroneous
readings may be obtained.
h. The FUNCTION, LINE
(E) and DROP (M)
keys should be normal unless required for
simultaneous sending. The LINE (E)key may
be operated to OFF
HOOK to make the trunk
busy toward the line. The
EXT DIAL CIRCUIT
switch is not in the measuring circuit. The
SPARK SUP turnbutton is not involved.

TTS 26B
Section 3
SELECTED BY AECEIM
SWITCH ONLY FOR ALL
POSlrlONS OF THIS SWTCH
U(CEPT EXTREME CLOWISE
POSmONS
LOOP
SRiNALW
0- 25 PPS
METER CIRCUIT
SWITCH
0-25 PPS
X BREM DIRECT
%BREAK THW METER RLY
METER CIRCUIT
SWITCH
'Figure 3-3b METER CIRCUIT