Service Manuals, User Guides, Schematic Diagrams or docs for : Keithley 600B 600B(Model60B)
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CONTENTS
SPECIFICATIONS MODEL
600B
SPECIFICATIONS
7
CONNECTORS: Input: Teflon4nrulared UHF Type. Out-
puo: &wrier srrip.
BATTERIES: Four 2N6 (or 246. VS305. NEDA 1602,; one
RM.IW. 700waur lxmerv life
DIMENSIONS. WEIGHT: 10~1/4" high x S-112" wide x
6-l/2" deep: net weight. 7.114 poundo.
ACCESSORIES SUPPLIED: Mating input connector.
0872R
MODEL 6008 ELECTROMETER GENERAL DESCRIPTION
SECTION 1. GENERAL DESCRIPTION
uremenfs with a minimum of adjustment. Zero drift with
rime is less than 2 m" per day. zero offset due to
temperature change is less than 200 microwits per %.
after a ,O-minute warm-up. This offset, however. can
easily be compensated for with the front-panel zero
controls.
b. fast wnrm UD is an inherent characteristic ok
this Electrometer. It can be used well wiehin 30
minutes of a cold scare on the mose sensitive range
and nlmosc immediately on less sensitive ranges.
d. `the ,"O-hour life ai rhe batteries enables us-
age in long-term experiments xiehauc interruptions
lulti=lier Switch setting possible
to obeain the best accuracy. The input resistor 3. !$ich the fast method, the input drop is re-
varies with the Range Switch setting. from 10 ohms duced and the response speed is increased at ieasc
at 10-l .u!PERES CO iUi! ohms for lo-11 AHPERES. 100 times. iiowever, follow rhese cautions:
The input voltage drop is the Meyer reading times
the Multiplier Switch serFin!. a\ The internal impedance ai the unknown cur-
rent should not be less the value oi
than .I ai
::mT. ihe Lardmck resistor wing "sea. Otherwise, ~iir
full feedbacK voltage cannot be developed at the
On the iaw current ranges, baiance out ihe input, and zero instability results. The feedback
oifset current vitb the Zero Controls or resistor value is the reciprocal of the AMPERES
suberacr ehe value from the reading. To range of the Range Switch.
find the amount of offset current, cap the
INPUT Receptacle and read the meter. b) The OHMS GUARD Terminal of the Barrier Strip
Cmnector is "a longer connected to case ground.
d. Fast Eleehod (ranges below 10-j ampere). Therefore. do "at use a grounded recorder. .is an
alternate. use the unity-gain output (paragraph
1. Fallow the inseructions of paragraph Z-1. 2-8).
see the conerois as follows:
C) Use,`with caution, the fast mechod to meas-
ZERO CHECK Sutton LOCK ure capacitor leakages. A very stable voltage
Range Switch lo-" AXPERES supply must be used. Connecting a capacitor fo
,Hultiplier Switch 1 the inpue changes the circuit to a differenciacor,
FEEDBACK Switch FAST resulting in extreme sensitivity to very small
METER Switch CENTER ZERO. voltage transients and a" increase in meter noise.
Connect the unknown source to the INPUT Receptacle e. Galvanometric Method.
and ""lock the ZE:.' ?LF.Y p:,?+-- =.- tL* `!--`"
Switch to t or -, as necessary. increase the se"- 1. Operate the Model 6008 as a picaammeter in
sitivity with chc I;ar,ge Sw,,ci~ a"- ~lir kurLIpiier the tast method. use an accurare reference current
Switch. DO not set the Range Switch to 1O-5 AHP- source s,,ch as the Keithley Model 261 to buck out
ERRS or higher. Check zero with the ZERO CHECK the unknown current source. connect as shown Fn
Button. Da nor short the input because this will Figure 5.
remove the feedback from the circuit.
"LlhSR 5
OPERATION MODEL 6008 ELECTROMETER
2. Set the METER Switch to CENTER ZERO and "se NOTE
the higher current rangas. Adjust the buckout cur-
rent to indicate null on the Model 6006. Increase Discharge any capacitor completely befare
the Electrometer sensitivity as needed. When the removing it from the circuit. Depressing
Node1 6008 is as close to null aa possible, the un- the ZERO CHECK Sutton shorts the input
known current is equal to the algebraic sum of the through a IO-megohm resistor, providing a
H.adel 261 setting and the Model 6008 current read- discharge path.
ine
b. Xormal constant Current Method (recommended f,ar
"se from 1 kilahm to 1011 ohms).
1. Set the controls as follows:
ZERO CHECK Butfo" LOCK
Range Switch 1011 OHMS
Multiplier Switch 1
FEEDBACK Switch NORMAL
XZTER Switch
Unlock the ZERO CHECK Button. Check zero only wit!:
the ZERO CHECK Button.
NOTE
Method. Cse an Llccur3te reference currene source CO
buck 0"~ ehe unknown c"rrenf s~"rce. The Eladel 6008, Do not open circuit the Electrameter 0" the
on its current ranges. ierves as a null detector. OHMS ranges; the input will develao "o f~
"se a UHF-tee ittlng at the Xodel 6008 input, con- 10 volts due to its consrant current charac-
nect the Elecz:Jmeter to the two s~"rces with CO.%- teristic. Keep the input shorted or the
ial cable. Select cable carefully for very low cur- ZERO CHECK Sutfon Locked.
rents (see parngrapil `-1).
2. The full-scale ohms range is the Hultiplier
Switch setting times the Range Switch setting. II s c
2-5. KLSISTANCE XEASUFGXZNTS. the smallest Range Switch se:cing possible to ob-
tain the best accuracy.
II. The Xodel 6000 can meas"re resistance by tw
merhads. 3. Before making a final :eading, manipulate ti:e
X~ltiplier and Range Switches. so the sample is
1. In the constant current methad, the Electrom- tested at a number of test potentials. The applier.
eter measures the voltage drop across the unknown test voltage is the percentage ai full scale that
_^__._...
sample as a knno;.r., _"...,-..... i..Zi'i;lCi L:u",r &`"ugiL the meter reads times the-X"iti?lier Switch seccin;.
it. The voltage drop is proportional to the resis-
tance Of the snmple. In this method the Model 6008 4. When the test current is applied, the high
can be used in one af ~0 different modes: normal terminal of the INPUT Receptacle is positive. The
or fast. test current is the reciprocal of the OHMS Range
setting.
a) The normal wj:r is trcommended for "se from
1 kilohm to 1011 ohms. NOTE
b) Above lOi ohms the fast method is prefer- Shield the inpue if the resistance sample
red. It results in faster respanse speed and exceeds lOa ohms.
also nullifies leakage across the Electrometer
input, since the pacential acr`oss the input ter- c. Fast Canstant C"rrent(C"ardedi Method (recom-
minal is small. mended for "se from 1011 to 1013 ohms).
2. In the preceding merhod, the voltage across 1. Follow the instructions of paragraph 2-2
the sample cannot be arbritrarily see. I" some set the controls as fallows:
cases. as in measuring capacieor leakage, this re-
sults in excessively long testing time. In the ZERO CHECK Button LOCK
voltmeter-anrmerer method the Moiri COGa is "sad as Range Switch 1012 OHMS
a picoammeter. The unknown resistance sample is Multiplier Switch 1
connected to an external known voltaee 80"rce and FEEDBACK Switch ?AST
ehe current through the sample is measured. Eith- METER Switch c
er the normal or fast method may be used. The re-
sistance is calculated from the readings. Connect the high impedance side of the resistance
sample to the INPUT Receptacle and the low impedance
side t" the OHMS GUARD Terminal. Unlock the ZERO
CHECK Button.
MODEL 6008 ELF.CTRO"ETER OPERATION
2. Read the resistance as in subparagraph b2 7. If the current is read by the face method,
above. the input drop Is so slight that it need not be in-
cluded in the calculation. If the capacity shunted
d. voltmeter-amecer Method (to 1016 ohms). acreee the sample is large, such as encountered in
capacitor leakage measurements. the faster methad
1. Turn the ZERO CHECK Switch to LOCK. Connect increases response speed and thFs cannectian is rec-
sample between INPUT receptacle and pawer supply. annended. Xate. however. Lhat power supply transi-
(see Figure 6). Put a switch in the high voltage ente will be magnified.
line to ground low impedance end af the sample when
it is disconnected from the potential. 2-6. CHARGE KSASUREMENTS
2. Set the FEEDBACK Switch to NORHAL. lJeilallp a. Follaw ehe instructiww of paragraph 2-2. see
this method is best, since inStabilities can arise the controls as follows:
for resistance samples less than 0.1 the value of
the feedback resistor. ZERO CHECK Button LOCK
Range Switch 10-7 CO"LOPBS
3. TO make e meaetiremenc. scare with switch S >lultFolier Switch .Ol
3s shown in Figure 6 and make sure the ZERO CHECK FEEDBACK sviech FAST
Sutton is set to LOCK. set switch S to apply e pa- XETER Switch CENTER ZERO
tential t~cross the samoie far a known period of
rime. ~!:en uniock rhe ZERO CHECK Gutcon and take
the reading. $9~ eke !:::;; rrc:: : I::.:::: "I:`--? ", ~>7n \`- preempiifier is needed. :;0 special wiring
is applied to the unknown resistance sample, I<,. The is required. when using the Node1 370 make sure the
Xodel 6008 measures the current through R,. from Recorder's sensitivity conrrol is set t0 maximum
wi,ich the resistance is calculated. Switch S connects (completely clackwise).
the low end of R, ea ground when na potential is
appiied.
oR72R 7
OPERATION MODEL 6008 ELECTROMETER
WARNING d. l-Milliampere Output: Connect l-milliampere
instruments to the OHMS GUARD Terminal and Terminal
The Model 6008 may be used with the FEEDBACK B on the Barrier Strip Connector and remove the shart-
Switch in FAST position with other instru- ing link. The output is approximately 1 milliampere
merits. However, make sure that the OHMS GUARD for full-scale meter deflection on any range. Fo=
terminal (output lo") is floating with respect exact output, adjust the meter on the .Ol volt range
to chassis ground. with the ZERO Control for full-scale deflection. The"
adjust the 1V - 1MA CAL Control until the recorder
c. I-Volt output. Place the shorting link between reads full scale. Check the recorder and meter zero
the OHMS GUARD Terminal and Terminal A. connect os- and repeat adjustment if necessary.
cilloecopes and pen recorder amplifiers to the OHMS
GUARD Terminal and Terminal S on the barrier strip
EO"*W.TtOC. Adjust the lv - LMA CAL Control for full-
scale recorder deflection to correspond with full- e. For servo rebalance recorders, use a divider of
scale meter deflection. Output is *l volt. Inter- approximately 1000 ohms total es show" in Figure 7.
nal resistance is 1000 ohms. I" this application the shorting link between OHMS
G'JARD and terminal `A" should be disconnected. The
value of the divider resistor should be one ohm for
every 1 m" OUtput.
f. When the FEEDBACK Switch is in the NORMAL pasi-
The METER Switch does not reverse the output polarity elan, the GUARD terminal of the Rarrier Strip Con-
Output polarity is opposite input polarity. nector is connected to the instrument case. mere-
fore. no difficulty will be experienced using oscil-
loscopes and recorders with the Node1 6008 set for
normal operation. In FAST position. however, Che
OHMS GUARD terminal is floating with respect to
chassis ground. Therefore the recordine instrumenr
must be capable of floating such es witi rhe Keithley
Model 370 Recorder,
2-S. UNITY GAIN OUTPUT. The unity-gain amplifier
can be used as a" impedance matching device to mini-
mize circuit loading errors
a. The unity-gain output is equal to the input
wi,thin 7.5 ppm when the load reeietance is 100 kilohms
or greater. By placing the Model 6008 between a IOn
FIGURE 7. Divider Clrc"its Acrosr Modri hnna "wv""' ohm source, For example, and J. 0.01% voltmeter with 1
for Driving 50 and LUU-millivolt Recorders. use 5% i-megohm input resisrance, overall accuracy better
resisrors in rhe dividers. The value of resistor R the" 0.025% ce" be achieved.
is one ohm far every 1mV of output.
I
FIGURE 8. bleanuring Pore"l~?l -6 !J?$ !.:---:I:.:.. c----L "I.;. ;.c;;i. Accuracy. The Model 6008 is used between
a high-resistance source. V,, and e 0.01% voltmeter to obtain high accuracy without causing circuit loading.
MODEL 6008 ELECTROMETER OPS~TION, CIRCUIT DESCRIPTION
1. Connece the voltmeter co ehe xl and OHMS far a precise zero adjustment.
GUARD Terminals as shown in Figure 8. The OHMS
GUARD Terminal is at ground with the FEEDBACK Switch b. When the FEEDBACK Switch is in FAST position,
in NORMAL. laxnwm output amplitude is 10 volts the unity-gain terminals permit more convenient con-
peak-to-peak? nections to oscilloscopes with a load resistance of
greeter than 100 kilohms without special precautions.
2. Adjust the Model 6008 zero Controls co obtain In this mode, the Xl Terminal is grounded and ehe
a zero-voltage reading on rhe exrernal voltmeter. OHMS GUARD Terminal delivers en output equal co the
Make cure the latter's sensitivity is high enough input signel.
SECTION 3. CIRCUIT DESCRIPTION
3-l. CESEUL. 2. The voleage drop across the amplifier is
a. The Keirhley Yodel bOOR is basically an eutreme-
ly stable and iinear dc ~volcmeter with a fuil-scale
sensitivity oi 10 millivoits and an input impedance of where & is the amplifier loop gain, greater t!lan
10L4 ohms shunted by 20 ?icoiarads. By using the frone 5 I 10' on all ranges.
p.nel controls, shunt m~istors and capacitors are se-
lected to make meesuremencs over a total ot 61 YOLC- c. `ihe complementary oufpot sK.ege, 4109 and 4110,
age, currene, fes~scance: .2nA *nl*lnmh -1"Z-E r?~~~,mt drives the amplifier ground at the same potential as
and resiseance dre measured using precision resistance ehe input signal. `Thus the input impedance is main-
stanaards, irom 10 ohm wirewound resistors to 1011 ohm tained for any value input voltage and the need for
glass sealed, deposited carbon resistors. coulombs input dividers is eliminated. `The amplifier *round
are measured using close tolerance polystyrene film is not chassis ground, hue it is connected directly
capacitor standards. to the unity gain output.
b. Batteries furnish the neceesarv amolifier oower. NOTE
3-2. "OLTHETER OPERATI(IN. Refer to Schematic Diagram 22BOSE for cir-
cuit designations.
a. The Model 6008 empioys matched insulated-gare,
field-effect transistors fallowed by a eransisror dif- 3-3. "OLTELETER CIRCUIT.
ferential amplifier with a high-voltage comvlementary
oueput stage. Figure 9 shows the block diagram for a. The amplifier input staSe is a pair of insulated
the voltmeter made of operation. gate, field-effect transiecars, Qlll and Qll5, in a
differential configuration. The gate of Qlll is re-
b. Voltmeter operation of the Model 6008 is as turned to amplifier common, the unity gain output.
fallows:
b. Depressing the ZERO CHECK Sutton, S102, places
1. The amplifier is always in a unity-gain, input the gate of the active insulated gate devices at zero
voltage co output current converter contigurarxm. p"LSLLLldl.
The internal circuitry is arranged such that a full
scale input voltage (ei) results in exactly a 1 mil- c. The input stage is fallowed by a transistor dif-
liampere outout curreoc through the divider string ferential amplifier. composed of QlOlA-QlOS. Q106 and
composed of Rm. R177, end the meter. Voltage gain Q107 make up the output gain stage, which is utilized
of the circuit is determined by the ratio of R177 to in e gain multiplier configureciao. This stage pro-
h. Output is taken across R177. vides the remainder of the high gain required by the
r%"L"D 9
CIRCUIT DESCRIZ'TION MODEL 6008 ELECTROMETER
UHF INPUT >i
amplifier. ALSO, this stage prevents fold-over and fed back to the amlll, GUARD and A Terminals on the Barrier Strip Connector.
are specislly selected nod matched; order only as a
plug-in unit, part number 23735 , from Keithley In-
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