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INSTRUCTION MANUAL
MODEL 710, 711
MILLIVOLT DISCRIMINATOR
MODEL
710/7ll COltTEnTs
TABLEOF coNTm
SECTION
INT~WCTION . . ..*.........*.....*.*......*....*.... I
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . ..~......#.
.. II
,.....,...........*..,..,*.*.,.....,....
DESCRIFTIO~ III
OPERATION . . . . . . . . . . . . ..*.....................*...
.. IV
MAINTENANCE.,....,..*....,...,......*....,,........ V
Voltage Chart
Schematic D1aSr.m
Replaceable Parts List
i
MODEL
710/711 INTROLWCTION
SECTIONI - 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. The range may be extended to 1000 volts with au internal
resistive divider, or to lo- ampere with a current shunt. Ad-
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. Dial setting
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.
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. On units wired to trip for a signal that
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. Input and output terminals are isolated
from each other and from ground.
Inmmnity to vibration and indefinite life under rigorous envimn-
mental conditions are assured by the use of premium subminiature
tubes and a Keithley designed photo-reeistive modulator having
no mating parts. Permissable overload is greater than 10,000
tines.
0762 l-l
MODEL 7LO/711 SPECIFICATIONS
SECTION - SPECIFICATIONS
II
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: Adjustment made with a calibrated dial
on the front panel. Dial setting of trip level is
accurate within +2COuV.
SENSITIVITY: 0.2 to 10 millivolts. Range can be extended to
1000 volts with an internal reoistive divider.
MAxIMuMSOURCE
IMPEDANCE: 100 K
INPUT IMPEDANCE:From Lo to GROUND INPUT to OUTPUT,over
or
1000 megohmsshunted by .0047 mfd. Across input terminals, greater
than lmegobm. Maximumvoltage above ground, 500 volts, dc or
peak.
OUTPUT: Relay contacts, DPDI!, 5 amps, IlO v, noninductive.
REPEATABILITY TRIP FOINT: Better than 200 microvolts.
OF
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: Positive or negative
0VERu)A.D: Greater than 10,000 times.
PERMISSIBLE
TRIP RESET: Automatic when the standard non-locking mode of
operation is used; differential between trip and reset is less
than 200 uv. Whenmodified for locking action, a reset switch
is added.
TRIP INDICATION: Red light on front panel.
VOLTAGE REFERENCE: One RM&XlRmercury battery. Battery life
is in excess of 10,000 hours.
1-6940; l-6788; 1-5643; l-m398
'RJBE, TPANSISMRCOMPLEMENT:
MODULA~RS: 2 Keithley Model 1510 Modulatora
KWER: x1.7 v, 60 cpe, I2 w; 230 v models on order
0762 2-l
dPECIFICA~ONS MODEL
710/7ll
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.
2-2 0762
MODEL
710/7ll DESCRIPTION
SECTIONIII - 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. signal at the grid of a thyratron. The thyratron
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 trans-
farmer secondary. This action is similar to a single-pole double-
throw 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. This ie the normal condition of operation,
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. The transistor, Cl protects against loss of
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.
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 maximumrejection to line frequency.
The demodulator circuit employs a four-diode bridge with silicon
diodes. A balanced configuration is used so that careful balance
of the transformer secondary is not necessary. The demodulator is
driven synchronously with the neon lamps which switch the input mod-
ulator . The demodulator output is a pulsating DC. signal which
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 3-l
MODEL
710/7ll OPERATION
SECTIONIV - OPERATION
A. INPUT CONNECTIONSThe 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 instrument is wired for the proper line volt-
w3=. The Model 71.0 and 7l.l will operate satisfactorily on 50 or 60
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.
C. NON-J&CKINC OPERATION The instrument is normally supplied
-
for non-locking operation and the relay will re-close when the signal
drops about 200 microvolts below the trip point.
D. LOCKING OPERATION CONVERSION ICCKINU OPERATION On the
AND T3 -
output plug at the rear of the instrument, pins (I) and (J) are jump-
ered. 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. Whenunits 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. REVERSEFOL4RITYOPEEATIONIf it is desired to operate with
-
negative signals the input signal is merely reversed.
F. OUTPUT CONNECTIONSThe output is obtained as a DPDTset of
-
contacts from a relay. The rating of the relay is 5 amperes NON-
IhWCTIvE. 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 recommendedthat the vacuum tube6 also be replaced
on that schedule.
TROUBLE
SHOOTING
CHART- MODEL and 711
7lO
SmM CAUSE TROUBLE
OF REMEDY CHECKS
AND
A.C. Power Cord plugged, Defective Power Cord, Plug Check Power source
pilot light does not or Receptacle and connections.
light and no readings Fuse (F-l) blown Fuse
obtained. Check (F-l)
No (+) voltage readings Defective MO1 Check D201. If
obtainable, pilot lamp necessary, replace.
lights and Relay Open
lamp (red) lights.
Rd.biy open Lamp (red) Defective V-1, V-2, or Check Tubes. Replace
on at aU times. v-3. if neceemry.
Defective B-l Check Battery. Ae-
place If necessary.
Open Potentiometer, R-120 Check for continuity.
Replace If neceeaary.
Open Relay Coil Check coil Resistance.
6200 ohms, t1oqb
N/O Relay Contact not Adjust
making
Defective D-102 Check D-102, replace
if necessary.
Jumper on Output Plug Check to 6ee If out-
put plug Is jumpered
between pins (I) and
(J)
Lamp (red) off, at all Defective IX-2 Check, replace if
times necessary.
Defective D-202, D-203 Check, replace If
D-204, or ~-205 neceaeary.
Defective C-l.lO Check, replace If
necessary.
Differential la greater Amplifier gain down Check voltage read-
than 200 microvolts IW.
Defective V-l, V-2, or V-3 Check, replace If
necessary.
0762~ 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
D- Junction of D-103 & D-105 (See Schematic)
E - 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
PARTSLIST
REPLACEABLE
PARTSLIST - mDEL -
710
Circuit
Deeig. Description Part No.
B-1 Battery, RM4Ol.-R ~a-8
c-101 Capacitor, mylar, .047 mfd. 200 V c47- .047
c-102 Capacitor, Sameas C-101
c-J.03 Capacitor, mylar, .1 mfd. 200 V. c47- .I.
c -1.04 Capacitor, cersmlc disc., .Olmfd, 6OOV. c22-.Ol
c-m5 Capacitor, Electrolytic 4.7 mfd, 15 V c71-4.7
c-106 Capacitor, Same as C-104
Capacitor, Ceramic d&x. .02 mfd, 600 V c22-.02
~:~!i Capacitor, Sameas C-107
c-109 Capacitor, Sameas C-107
c-ILL.0 capacitor, R1cctroly"clc, 50 mfd. 6 V. Cl7"50
C-IJJ. Capacitor, Same as C-101
c-u.2 Capacitor, Ceramic Disc. 47 PF cn-47
c-u3 Capacitor, Cersmlc D:Lsc. .0047 mfd.: 6OOV. C22-.0047
c-u.4 Capacitor, Metallzecl paper tubular, lmfd 200V ~18-1.0
c-201 Capacitor, Dry Electrolytic tibular, 20 mfd.,
250 v. Ix: C27-20
C-20% Capacitor, Same as C-201
C-203 Capacitor, Sameas C-201
c-2oh Capacitor, Drv Electrolvtlc Tubular. 1000 mfd.
-i%v.li! - cll-1000
D-101 Rectifier, 1.~2069
t- D-106 RF-20
D-201
thru ~-205 Rectlfler, lN2O7l w-17
F-1 Fuse, .5 A Slow Blow JRJ-4
Ds-1 Light Assembly, Pilot #47 PL-I.30
Ds-2 Light Assembly, Pilot #I+7 FL-13R
J-2 Jack, Input - Cannon KLR-3-32 cs-71
J-1 Jack, output - Amphenol AN 3102~-18-~(c) cs-23
P-1 P1ug, Output - Amphenol.AN 3106-A-1&W cs-22
P-2 Plug, Input - Cannon XI&-3-U. cs-72
R-101 Resistor, Composition, 22M, lOgb, -$ watt Rl-22M
R-102 Resistor, Deposited Carbon, 6OK; l$, * watt RI%6OK
R-103 Resistor, Deposlted Carbon, 23.3K, 15, -$ watt RX?-23.3K
R-104 Potentiometer, Carbon, 1OK RP2-1OK
R-105 Resistor, Deposited Carbon, 4OK, l$, $ watt IW-40K
~-106 Potentiometer, Carbon, 20K RP7-20K
R-107 Resistor, Composition 1OOK, lO$, $ watt Rl-LOOK
R-108 Resistor, Composition 3.3M, 10$, 7 watt Rl-3.3M
R-109 Resistor, Composition 4.7K, l.O$, 7 watt Rl-4.7K
R-l.20 Resistor, Composition 27OK, lo%, ?; Watt Rl-270K
0762~ 5-3
REPLACEABLE
PARTSLIST MODEL
710/7l.l
R.WLACEABLE
PARTSLIST -I#JDELE
cj.rcuit
Desig. Description Part No.
R-XLI. Resistor, Composition lOM, lO$, & watt R&MM
R-U.2 Resistor, Composition, 47OK, LO$, $ wstt Rl-470K
R-L13 Resistor, Same as R-Ill
R-U.4 Resistor, Sameas R-107
R-U.5 Resistor, Composition, ~&XC, 10sl. 4 watt Rl-28OK
R-n6 Resistor, Composition, IX, I&, 3 watt Rl-l.K
R-XL7 Resistor, Same as R-107
~-x1.8 Resistor, Ssme as R-107
R-U.9 Resistor, Composltion, 47K, lO$, $ watt RI-47K
R-120 Potentiometer, Trimpot Wirewound., 3x Im9-l.K
R-121 Resistor, Wirewound, l2OK, l$, t watt R18-2X-UOK
R-201 Resistor, Coqositlon, IK, lO$, + watt Rl-W.
R-202 Resistor, Sameas R-201
~-203 Resistor, Sameas R-IL9
R-204 Resistor, Sameas R-107
~-205 Resistor, Composition, l2OK lO$, &watt RLl20K
R-206 Resistor, Composition lO$, & watt, 4.7 K Rl-4.7K
R-207 Resistor, Composition, 330 ohms, 105, s watt Rl-330
R-208 Resistor, Wirewound, 25 ohm, 5$, 5 watt R4A-25
K-l Relay, P&B - MJ-XZ~~ RLI-14
T-l !&ansformer (Central u-176) l!R-43
V-l Vacuum Tube, Sylvania 6788 nr-6788
v-2 Vacuum Tnbe, Sylvania 6948 m-6948
v-3 Vacuum Tube, Sylvania 5643 m-5643
Q-1 Transistor , RCA~398 m-13
PDLOl Components of Model I.501 Light Mod. Aseembb 13085~
EN101 Components of Model 1501 Light Mod. Assembly 13085~
PD102 Components of Model 1501 Light Mod. Assembly 13085A
EN102 Components of Model1501 Light Mod. Assembly 13085~
5-4 0762R
MODEL 710/711 REPLACEABLE PARTS
REPLACEABLE PARTS LIST - NODEI, 711
Circuit Kei,thley
Desig. Description Part. No.
B 1. Battery, RH401-R BA-8
Cl01 Capacitor, mylar, .047 mfd. 200 V c47-,047
Cl02 Capacitor, same as Cl01
Cl03 Capacitor, Mylar, .l mfd. 200 V c47-.l
Cl04 Capacitor, cerainic disc. , .Ol mfd. 600 v c22-.Ol
Cl05 Capacitor, Electrolytic, 4.7 mfd; 15 W c71-4.7
Cl06 Capacitor, Same as Cl04
Cl07 Capacitor, Ceramic disc. .02 mfd. 600 V c22-.02
Cl08 Capacitor, same as Cl07
Cl09 Capacitor, Same as Cl07
Cl.10 Capacitor, Electrolytic, 50 mfd. 6 V c17-50
Cl11 Capacitor, Same as Cl01
Cl12 Capacitor, Ceramic disc. 47 PF C22-47
Cl13 Capacitor, Ceramic disc. .0047 mfd. 600 V C22-.0047
Cl14 Capacitor, Mylar, 1 mfd 200 V C66-1.0
a01 Capacitor, Dry Electrolytic Tubular., 20 mid. 250 V DC C27-20
c202 Capacitor, Same as C201
C203 Capacitor, Same as C201
C204 Capacitor, Dry Electrolytic Tubular, 1000 mfd. 12 V DC Cll-1000
El01 Rectifier, lN2071 RF-17
D102 Rectifier, lN2071 RF-17
Dl03 Rectifier (1)
Dl04 Rectifier (2)
D1.05 Rectifier (1)
D106 Rectifier (2)
D201 Rectifier, lN2071. RF-17
D202 Rectifier, lN2069 RF-20
t11ru
D205
Fl FU-4
Wl. Light Assmcbly, Pi.lot ih7 PL-13G
DS2 " Light Assmebly , Pilot i/47 PI.-1~3R
(I) D103 and Dl.05 arc macchrd, Keithl~~y Part No. 14168A, replace only as a pai,r.
(2) D~OLI.and DI~OGare matched, Kci~thl~ey Part No. 1416811, replace only as a pair.
Ii) ,:;"
RISPLACEABLEPARTS MODEI. 71Of71.1
REPLACEABLEPARTS LIST - MODEL 711 (Cont'd)
Circuit Keithlfy
Desig. Descripti.ou _----l_l^^.-._ll__- Part 11__.-..;1
No.
~----~- .---_~ .._
52 Jack, Input - Cannon XLR-3-32 cs-71
Jl Jack, Output - Amphenol AN 3,lO2A-18-IS(C) CS-23
Pl Plug, Output - A~n~>lrenolAN 3106-A-18-1P cs-22
P2 Plug, Input - cannon XLR-3-11 CS-72
RlOl Resistor, Composition, 2.2H;lO%, 112 watt Rl-2.2M
R102 Resistor, Deposited Carbon, 6OK., l%, l/2 watt Rl2-60J<
R103 Resistor, Deposited Carbon, 23.3K, I.%, I.12 watt R12-23.31:
RlO4 Potcnti.orneter, Carbon, 1OK RP2-1OK
K105 Resistor, Deposi~ted Carbon, 40K, l%, l/2 watt R12-4.0K
R106 Potentiometer, Carbon, 2OK RP7-20K
R107 Resistor, Composition lOOK, lo%, l/2 watt Rl-1OOK
R108 Resistor, Composition 3.3M, lo%, l/2 watt Rl-3.3M
R,109 Resistor, Composition 4.7K, IO%, l/2 watt Rl-4. 7K
RllO Resistor, Composition 270K, lo%, l/2 watt R1..270K
Rlll~ Resistor, Composition, lOM, lo%, l/2 watt RI-1OM
R112 Resistor, 'Composition 47OK, lo%, l/2 watt R1-[1,70K
R113 Resistor, Same as Rlll
R114 Resistor, Same as R107
R1.15 Resistor, Composition, 18OK, lo%, l/2 watt Rl-180K
R116 Resistor, Composition, lK, lo%, l/2 watt Rl-1K
R117 Resistor, Same as R107
_ --
R118 Resistor, Same as RLU/
R119 Resistor, Composition, 47K, lo%, l/2 watt R1 - 11.K
7
R120 Potentiometer, Wirewound, 1K RP28-1K
R121 Resistor, Wirewound, 12OK, I~%, l/4 watt R18-6-120K
R122 Potentiometer, Trimpot Wirewound, 10K RP39-10K
R201 Resistor, Composition, lK, lo%, l/2 watt Rl-1K
R202 Resistor, Same as R201
R203 Resistor, Same as Rll9
R20(1. Resistor, S me as R107
R205 Resistor, ComposLtion, 12OK, lo%, l/2 watt Rl-120K
~206 Resistor, Composition, 4.7K, lo%, l/2 watt RI-4.7K
R207 Resistor, Composition, 330 ohms, lo%, l/2 watt Rl-330
R208 Resistor, 0
Wi.rewound, 25 ohm, 5/,, 5 watt R4A-25
ticlay, P &'F,- Ml?-1287 m-14
Transformer (Central Kl-176) TR-43
- -
-
L -
-. -
-
-
7
-
- - ti
1 L -
LL
L
/
-
/
- -
,
#
SClNO:,3SllllW NI 3WIl dlU1
M~DEL..7lO-711
VOLTAGE $ F?ES\S-l-AE\\CE CHART
MADE FROMTUB~
WITH \NPUT
TO GROUND,
AND "TRIP LEVEL" AD J. FOR M\N.
W\Tl-l "RELAY OP-EN " L\GHT OFF.
USE VTVM FOR MEASURIZMEhlTS
+I.65v
V-l
+
(41'7K)i; 8SV
+6SY
2
F
( I5PK) 3
fapx! 71oj72.l MAINTENANCE
c*,-`z
D.
.":-`7
Ii +
E. ij
ri.iiA
1.5 v P-P
t
0862R 5-9