INSTRUCTION MANUAL
MODEL 710, 711
MILLIVOLT DISCRIMINATOR
MODEL 710/7ll COltTEnTs
TABLE OF coNTm
SECTION
INT~WCTION . . ..*.........*.....*.*......*....*....
SPECIFICATIONS
DESCRIFTIO~
. . . . . . . . . . . . . . . . . . . . . . . . . . ..~......#. II
,.....,...........*..,..,*.*.,.....,.... III
OPERATION . . . . . . . . . . . . . . ..*.....................*...
MAINTENANCE
.,....,..*....,...,......*....,,........
Voltage Chart
Schematic D1aSr.m
Replaceable Parts List
I
IV
V
i
MODEL 710/711
SECTION I - IN'J!ROIlJCTION
A. Models 710 and 7ll MilUvolt Discriminators
These Millivolt Discriminatorn are extremely stable, light-
modulator clc amplifiers operating a thyratron tube end reley.
They are identical except for the method of the trip level
adjustmenta.
Trip level of the 710 and 7l.l is variable from 0.2 to 10 milli-
volts.
resistive divider, or to lo-
justment of the 710 is made with an external reference aad po-
tentiometer located behind the front panel. The 711 is adjusted
by means of a calibrated dial in the front panel.
is accurate within 2200 uv .
The instnuncnts may be made either locking or non-locking.
They are chatter-free on non-locking and locking operation;
modification for locking action is easily made by adding a nor-
mally open switch.
The range may be extended to 1000 volts with au internal
ampere with a current shunt.
INTROLWCTION
Ad-
Dial setting
Long term repeatability of the 710 and 711 is better than 200
micmvoltn, and the speed of response is between k~ end 60
milliseconds with a signal 5% larger than the trip level.
Standard units are wired to trip for signals exceeding the trip
point and are fail-safe in that failure of any component cause6
the alarm condition.
decreases below the trip point, the unit is not fail-safe if
a loss of reference signal occurs.
Careful shielding, filtering, and guarding permit floating oper-
atlon up to 500 volts above ground, with excellent rejection
to extraneous voltages.
from each other and from ground.
Inmmnity to vibration and indefinite life under rigorous envimnmental conditions are assured by the use of premium subminiature
tubes and a Keithley designed photo-reeistive modulator having
no mating parts.
tines.
On units wired to trip for a signal that
Input and output terminals are isolated
Permissable overload is greater than 10,000
0762
l-l
MODEL 7LO/711
SPECIFICATIONS
SECTION II -
SPECIFICATIONS
Models 710 and 711 are identical except for the means of adjust-
ing the trip level.
TRIP LrnL: Model 710: Adjustment made with an external refer-
ence and potentiometer located behind front panel.
Model 7l.l:
on the front panel.
Adjustment made with a calibrated dial
Dial setting of trip level
is
accurate within +2CO uV.
SENSITIVITY:
0.2 to 10 millivolts.
Range can be extended to
1000 volts with an internal reoistive divider.
MAxIMuM SOURCE IMPEDANCE: 100 K
INPUT IMPEDANCE: From Lo to GROUND or INPUT to OUTPUT, over
1000 megohms shunted by .0047 mfd.
than lmegobm.
Maximum voltage above ground, 500 volts, dc or
Across input terminals, greater
peak.
OUTPUT:
REPEATABILITY OF TRIP FOINT:
Relay contacts, DPDI!, 5 amps, IlO v, noninductive.
Better than 200 microvolts.
STABILITY OF TRIP FOINT:
+-0.3% with +lO$ line change.
60 CR3 REJECTION: 100 millivolts of 60 cps on dc signal will
cause less than 1% shift of trip point;
RESPONSE SPEED: As shown in Figure 1, speed depends somewhat
on the degree to which the trip point is exceeded. Reclosure
time ia approximately 30 milliseconds.
TRIP POLARITY:
PERMISSIBLE 0VERu)A.D:
TRIP RESET:
Positive or negative
Greater than 10,000 times.
Automatic when the standard non-locking mode of
operation is used; differential between trip and reset is less
than 200 uv.
When modified for locking action, a reset switch
is added.
TRIP INDICATION:
VOLTAGE REFERENCE:
Red light on front panel.
One RM&XlR mercury battery. Battery life
is in excess of 10,000 hours.
'RJBE, TPANSISMR COMPLEMENT:
1-6940; l-6788; 1-5643; l-m398
MODULA~RS:
KWER:
2 Keithley Model 1510 Modulatora
x1.7 v, 60 cpe, I2 w; 230 v models on order
0762
2-l
dPECIFICA~ONS
ACCESSORIES SUPPLIED: MatIn@; connectors; input, outputi
ACCESSORIES AVAILABLE: Model 7105 Case: Model 7102 Rack Freme
for mounting up to 7 UnIta.
DlldENSIONS: 8" high x 2#" wide x 13$’ deep.
MODEL 710/7ll
2-2
0762
MODEL 710/7ll
SECTION III - DESCRIPTION
The Model 710 and 711 Millivolt Discriminators consist of a three
stage vacuum amplifier following a modulator and an input filter.
The output of the amplifier is synchronously demodulated and filtered
to provide a D.C.
controls a relay.
The input contains the D.C. to A.C. modulator, an input filter to
reject spurious AX. signals and the Trip Level reference set.
The modulator used in the Millivolt Discriminator employs two photo-
conductive cells, PD-101 and PD-102, which operate from the transfarmer secondary. This action is similar to a single-pole doublethrow mechanical chopper with the result that the D.C. input and
the D.C. reference are converted to an A.C. signal. With no signal
at the input of the amplifier either from the reference or the input,
the negative bias cuts off the thyratron and the relay drops out.
When a reference signal is fed to the amplifier, the negative bias
at the grid of the thyratron is cancelled and the thyratron fires
and energizes the relay.
that is with the relay energized. Operating in this manner the Model
710 and "(11 will indicate an alarm condition in the event of any
tube failure in the unit or from the loss of this reference signal
by any other means.
bias on the thyratron. If bias is lost, the transistor opens the
cathode circuit of V3 and gives the alarm condition. The modulator
compares the input signalto the signal set by the Trip Level. If
the input signal is less than the level set by the Trip Level pot.,
the D.C. voltage to the thyratron grid keeps the thyratron on. If
the input signal exceeds the reference signal the tbyratron extinguishes
and indicates the alarm condition by means of a red light on the
front panel.
signal at the grid of a thyratron.
This ie the normal condition of operation,
The transistor, Cl protects against loss of
DESCRIPTION
The thyratron
Spurious AX. signals are prevented from entering the input by means
of a "twin-tee" filter consisting of R-102 through R-106 and C-101
through C-103 which is tuned to line frequency. X-104 and R-106
are set at the factory for maximum rejection to line frequency.
The demodulator circuit employs a four-diode bridge with silicon
diodes.
of the transformer secondary is not necessary.
driven synchronously with the neon lamps which switch the input modulator .
is filtered and fed to the grid of the thyratron.
The basic sensitivity of the instrument is 10 millivolts, however,
reduced sensitivity may be obtained by the use of a divider.
The output is obtained as a D.P.D.T. set of contacts from a relay
which is used for control.
0762
A balanced configuration is used so that careful balance
The demodulator is
The demodulator output is a pulsating DC. signal which
3-l
MODEL 710/7ll
OPERATION
SECTION IV - OPERATION
A.
INPUT CONNECTIONS - The Model 710 and 71.1 will operate grounded
or floating. For grounded operation, one side of the signal source
should be grounded.
B. OPERATION - The power is turned on by plugging in the power
cord. Be sure that the
w3=.
The Model 71.0 and 7l.l will operate satisfactorily on 50 or 60
instrument
is wired for the proper line volt-
cps. For method of changing from ll.5 to 230 volts consult schematic.
The trip point on the Model no is set by means of an &X%nal.
reference and a multi-turn wire wound potentiometer located
behindths frontpaslelandontheModel71lbymeans of a cal-
ibrated dial on the front panel. !cheFEIAromilightviu.go
on-when the
limit
is
mceeded.
No other operating adjustment
is necessary.
NON-J&CKINC OPERATION - The instrument is normally supplied
C.
for non-locking operation and the relay will re-close when the signal
drops about 200 microvolts below the trip point.
LOCKING OPERATION AND CONVERSION T3 ICCKINU OPERATION - On the
D.
output plug at the rear of the instrument, pins (I) and (J) are jumpered. if this jumper is raved, the unit will perform as a locking
relay.
To reset, pins (I) and (J) must be ~mentarily shorted after
the signal has fallen below the set limit. When units are supplied
as locking relays, a reset button, connected across pins (I) and (J),
is mounted on the front panel.
Remote reset may be obtained by an
external control across the reset pins.
E. REVERSEFOL4RITYOPEEATION
- If it is desired to operate with
negative signals the input signal is merely reversed.
F.
OUTPUT CONNECTIONS
- The output is obtained as a DPDT set of
contacts from a relay. The rating of the relay is 5 amperes NONIhWCTIvE.
If inductive loads or higher currents are to be switched,
the output should be followed by a second relay of high enough cur-
rent capacity.
0762
4-l
MODEL 7101711 MAINTENANCE
SEXXTONV
-MAINTENANCE
The only maintenance required Is the replacement of the mercury
standard cell every 10,000 hours. If the highest rellabl1lty Is
required, It le recommended that the vacuum tube6 also be replaced
on that schedule.
TROUBLE SHOOTING CHART - MODEL 7lO and 711
SmM
A.C. Power Cord plugged,
pilot light does not or Receptacle
light and no readings Fuse (F-l) blown
obtained.
No (+) voltage readings
CAUSE OF TROUBLE REMEDY AND CHECKS
Defective Power Cord, Plug Check Power source
and connections.
Fuse
Check (F-l)
Defective MO1
Check D201. If
obtainable, pilot lamp necessary, replace.
lights and Relay Open
lamp (red) lights.
Rd.biy
on at
open Lamp (red)
aU times. v-3.
Lamp (red) off, at all
times
Defective V-1, V-2, or
Defective B-l
Open Potentiometer, R-120
Open Relay Coil
N/O Relay Contact not
making
Defective D-102
Jumper on Output Plug
Defective IX-2
Defective D-202, D-203
D-204, or ~-205
Defective C-l.lO
Check Tubes. Replace
if neceemry.
Check Battery. Aeplace If necessary.
Check for continuity.
Replace If neceeaary.
Check coil Resistance.
6200 ohms, t1oqb
Adjust
Check D-102, replace
if necessary.
Check to 6ee If output plug Is jumpered
between pins (I) and
(J)
Check, replace if
necessary.
Check, replace If
neceaeary.
Check, replace If
necessary.
Differential la greater Amplifier gain down
than 200 microvolts
Defective V-l, V-2, or V-3 Check, replace If
0762~
Check voltage read-
IW.
necessary.
5-l
l&I.NTENANCE MODEL 7l.O/7ll
The waveform8 In Figure (2) have been prepared to help check for
proper operation and localize a possible malfunction.
To o'btain the waveforms, Short the input leads to chassis. Set the
trip level. pot for 1 mv and connect an oocilloscopo between chassis
and the points indicated below:
Figure (1)
A - V-l, Pin 5
B- v-2, Pin 1
c -
V-2, PLn 8
Junction of D-103 & D-105 (See Schematic)
DE
- V-3, Pin 7
Failure to obtain the desired waveform at any of the above points
would Indicate the fault to be at that stage or some component pre-
ceedlng It.
Use conventional AC Amplifier trouble-shootlug methods ito localize
fault.
Refer to Schematic and Voltage & Resistance Chart.
s-2
0762
MODE& 71Oi73.l
FIXPLACEABLE PARTS LIST
Circuit
Deeig.
B-1
c-101
c-102
c-J.03
c -1.04
c-m5
c-106
~:~!i
c-109
c-ILL.0
C-IJJ.
c-u.2
c-u3
c-u.4
c-201
C-20%
C-203
c-2oh
REPLACEABLE PARTS LIST - mDEL 710
-
Description
Battery, RM4Ol.-R
Capacitor, mylar, .047 mfd. 200 V
Capacitor, Same as C-101
Capacitor, mylar, .1 mfd. 200 V.
Capacitor, cersmlc disc., .Olmfd, 6OO
V.
Capacitor, Electrolytic 4.7 mfd, 15 V
Capacitor, Same as C-104
Capacitor, Ceramic d&x. .02 mfd, 600 V
Capacitor, Same as C-107
Capacitor, Same as C-107
capacitor, R1cctroly"clc, 50 mfd. 6 V.
Capacitor, Same as C-101
Capacitor, Ceramic Disc. 47 PF
Capacitor, Cersmlc D:Lsc. .0047 mfd.: 6OO V.
Capacitor,
Metallzecl
paper tubular, lmfd 200V ~18-1.0
Capacitor, Dry Electrolytic tibular, 20 mfd.,
250 v. Ix:
Capacitor, Same as C-201
Capacitor, Same as C-201
Capacitor, Drv Electrolvtlc Tubular. 1000 mfd.
-i%v.li! -
Part No.
~a-8
c47- .047
c47- .I.
c22-.Ol
c71-4.7
c22-.02
Cl7"50
cn-47
C22-.0047
C27-20
cll-1000
D-101
t- D-106
D-201
thru ~-205
F-1
Ds-1
Ds-2
J-2
J-1
P-1
P-2
R-101
R-102
R-103
R-104
R-105
~-106
R-107
R-108
R-109
R-l.20
Rectifier, 1.~2069
Rectlfler, lN2O7l
Fuse, .5 A Slow Blow
Light Assembly, Pilot #47
Light Assembly, Pilot #I+7
Jack, Input - Cannon KLR-3-32
Jack, output - Amphenol AN 3102~-18-~(c)
P1ug, Output - Amphenol. AN 3106-A-1&W
Plug, Input - Cannon XI&-3-U.
Resistor, Composition, 22M, lOgb, -$ watt
Resistor, Deposited Carbon, 6OK; l$, * watt
Resistor, Deposlted Carbon, 23.3K, 15, -$ watt
Potentiometer, Carbon, 1OK
Resistor, Deposited Carbon, 4OK, l$, $ watt
Potentiometer, Carbon, 20K
Resistor, Composition 1OOK, lO$, $ watt
Resistor,
Composition 3.3M, 10$, 7 watt
Resistor, Composition 4.7K, l.O$, 7 watt
Resistor, Composition 27OK, lo%, ?; Watt
RF-20
w-17
JRJ-4
PL-I.30
FL-13R
cs-71
cs-23
cs-22
cs-72
Rl-22M
RI%6OK
RX?-23.3K
RP2-1OK
IW-40K
RP7-20K
Rl-LOOK
Rl-3.3M
Rl-4.7K
Rl-270K
0762~
5-3
REPLACEABLE PARTS LIST
R.WLACEABLE PARTS LIST -I#JDELE
cj.rcuit
Desig.
Description
MODEL 710/7l.l
Part No.
R-XLI.
R-U.2
R-L13
R-U.4
R-U.5
R-n6
R-XL7
~-x1.8
R-U.9
R-120
R-121
R-201
R-202
~-203
R-204
~-205
R-206
R-207
R-208
K-l
Resistor, Composition lOM, lO$, & watt
Resistor,
Composition, 47OK, LO$, $ wstt
Resistor, Same as R-Ill
Resistor, Same as R-107
Resistor, Composition, ~&XC, 10sl. 4 watt
Resistor, Composition, IX, I&, 3 watt
Resistor, Same as R-107
Resistor, Ssme as
R-107
Resistor, Composltion, 47K, lO$, $ watt
Potentiometer, Trimpot Wirewound., 3x
Resistor, Wirewound, l2OK, l$, t watt
Resistor, Coqositlon, IK, lO$, + watt
Resistor, Same as R-201
Resistor, Same as R-IL9
Resistor, Same as
R-107
Resistor, Composition, l2OK lO$, &watt
Resistor, Composition lO$, & watt, 4.7 K
Resistor,
Composition, 330 ohms, 105, s watt
Resistor, Wirewound, 25 ohm, 5$, 5 watt
Relay, P&B - MJ-XZ~~
T-l !&ansformer (Central u-176)
R&MM
Rl-470K
Rl-28OK
Rl-l.K
RI-47K
Im9-l.K
R18-2X-UOK
Rl-W.
RLl20K
Rl-4.7K
Rl-330
R4A-25
RLI-14
l!R-43
V-l
v-2
v-3
Q-1
PDLOl
EN101
PD102
EN102
Vacuum Tube, Sylvania 6788
Vacuum Tnbe, Sylvania 6948
Vacuum Tube, Sylvania 5643
Transistor , RCA ~398
Components of Model I.501 Light Mod. Aseembb
Components of Model 1501 Light Mod. Assembly
Components of Model 1501 Light Mod. Assembly
nr-6788
m-6948
m-5643
m-13
13085~
13085~
13085A
Components of Model1501 Light Mod. Assembly 13085~
5-4
0762R
MODEL 710/711
REPLACEABLE PARTS
REPLACEABLE PARTS LIST - NODEI, 711
Circuit
Desig.
B 1.
Cl01
Cl02
Cl03
Cl04
Cl05
Cl06
Cl07
Cl08
Cl09
Cl.10
Cl11
Cl12
Cl13
Cl14
a01
c202
C203
C204
Description
Battery, RH401-R
Capacitor, mylar, .047 mfd. 200 V
Capacitor,
same as Cl01
Capacitor, Mylar, .l mfd. 200 V
Capacitor, cerainic disc. ,
.Ol mfd. 600 v
Capacitor, Electrolytic, 4.7 mfd; 15 W
Capacitor, Same as Cl04
Capacitor, Ceramic disc. .02 mfd. 600 V
Capacitor, same as Cl07
Capacitor, Same as Cl07
Capacitor, Electrolytic, 50 mfd. 6 V
Capacitor, Same as Cl01
Capacitor, Ceramic disc. 47 PF
Capacitor, Ceramic disc. .0047 mfd. 600 V
Capacitor, Mylar, 1 mfd 200 V
Capacitor, Dry Electrolytic Tubular., 20 mid. 250 V DC
Capacitor, Same as C201
Capacitor, Same as C201
Capacitor, Dry Electrolytic Tubular, 1000 mfd. 12 V DC
Kei,thley
Part. No.
BA-8
c47-,047
c47-.l
c22-.Ol
c71-4.7
c22-.02
c17-50
C22-47
C22-.0047
C66-1.0
C27-20
Cll-1000
El01
D102
Dl03
Dl04
D1.05
D106
D201
D202
Rectifier, lN2071
Rectifier, lN2071
Rectifier
Rectifier
Rectifier
Rectifier
Rectifier, lN2071.
Rectifier, lN2069
t11ru
D205
Fl
Wl.
DS2 "
Light Assmcbly, Pi.lot ih7
Light Assmebly , Pilot i/47
(I) D103 and Dl.05 arc macchrd, Keithl~~y Part No.
(2) D~OLI. and DI~OG are matched,
Kci~thl~ey Part No. 1416811, replace only as a pair.
RF-17
RF-17
(1)
(2)
(1)
(2)
RF-17
RF-20
FU-4
PL-13G
PI.-1~3R
14168A, replace only as a pai,r.
Ii) ,:;"
RISPLACEABLE PARTS
MODEI. 71Of71.1
REPLACEABLE PARTS LIST - MODEL 711 (Cont'd)
Circuit
Desig.
~----~-
52
Jl
Pl
P2
RlOl Resistor, Composition, 2.2H;lO%, 112 watt
R102
R103
RlO4 Potcnti.orneter, Carbon, 1OK
K105
R106
R107
R108
R,109
RllO
Rlll~
R112
R113
R114
R1.15
Jack, Input - Cannon XLR-3-32
Jack, Output - Amphenol AN 3,lO2A-18-IS(C)
Plug, Output
Plug, Input - cannon XLR-3-11
Resistor, Deposited Carbon, 6OK., l%, l/2 watt
Resistor,
Resistor, Deposi~ted Carbon, 40K, l%, l/2 watt
Potentiometer, Carbon, 2OK
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Deposited Carbon, 23.3K, I.%, I.12 watt
Composition lOOK, lo%, l/2 watt
Composition 3.3M, lo%, l/2 watt
Composition 4.7K, IO%, l/2 watt
Composition 270K, lo%, l/2 watt
Composition, lOM, lo%, l/2 watt
'Composition 47OK, lo%, l/2 watt
Same as Rlll
Same as R107
Composition, 18OK, lo%, l/2 watt
Descripti.ou Part No.
.---_~ .._
- A~n~>lrenol AN 3106-A-18-1P
_----l_l^^.-._ll__- 11__.-..;1
Keithlfy
cs-71
CS-23
cs-22
CS-72
Rl-2.2M
Rl2-60J<
R12-23.31:
RP2-1OK
R12-4.0K
RP7-20K
Rl-1OOK
Rl-3.3M
Rl-4. 7K
R1..270K
RI-1OM
R1-[1,70K
Rl-180K
R116
R117
R118
R119
R120
R121
R122
R201
R202
R203
R20(1.
R205
~206
R207
R208
Resistor,
Resistor,
Resistor,
Resistor,
Potentiometer, Wirewound, 1K
Resistor, Wirewound, 12OK, I~%, l/4 watt
Potentiometer, Trimpot Wirewound, 10K
Resistor, Composition, lK, lo%, l/2 watt
Resistor, Same as R201
Resistor, Same as Rll9
Resistor,
Resistor, ComposLtion, 12OK, lo%, l/2 watt
Resistor, Composition, 4.7K, lo%, l/2 watt
Resistor, Composition, 330 ohms, lo%, l/2 watt
Resistor, Wi.rewound, 25 ohm, 5/,, 5 watt
ticlay, P &'F,- Ml?-1287
Composition, lK, lo%, l/2 watt
Same as R107
Same as RLU/
Composition, 47K, lo%, l/2 watt
S me as R107
_ --
0
Rl-1K
R 1 - 11. 7 K
RP28-1K
R18-6-120K
RP39-10K
Rl-1K
Rl-120K
RI-4.7K
Rl-330
R4A-25
m-14
Transformer (Central Kl-176)
TR-43
-
-
-
-
-
-
L
-.
1
L
7
-
L
-
-
-
ti
LL
-
/
-
/
-
SClNO:,3SllllW NI 3WIl dlU1
,
#
M~DEL..7lO-711
VOLTAGE $ F?ES\S-l-AE\\CE CHART
MADE FROMTUB~
WITH \NPUT
TO
AND “TRIP LEVEL” AD J. FOR M\N.
W\Tl-l “RELAY OP-EN ” L\GHT OFF.
USE VTVM FOR MEASURIZMEhlTS
+I.65v
GROUND,
V-l
+
(41’7K)i;
+6SY
(
I5PK)
8SV
2
F
3
fapx! 71oj72.l
MAINTENANCE
c*,-‘z
D.
.“:-‘7
E.
ri.iiA
Ii
ij
+
1.5 v P-P
t
0862R 5-9
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