ATOMIC ENERGY COMMISSION
MAINTENANCE EXPERIENCE AND DEVELOPMENT
i i ..**,i ..
I'jlli a !*.* ."' **in .* *'
ni*.i .:! .* *
* -* *...*. H ..
* ** I
i .~f : *: **\i .
i $:-hlished f
: .*. ca qu
s **' 1i" h .
W. T. E
or use within the Atomic Energy Commis
istions regarding reproduction- by recipients of this docu
nical Information Division, Atomic Energy Commission,
for additional copies
,ment may be referred
P. O. Box E
, Oak Ridge,
i:much as a declassified document may differ materially from the original cla
*Au *C2~ f--CHI
.... I .
A ..: :* |'E
-- W- **** I Ji
*.. ..i..n..... *
*Illl *4 i
i fx *. :
Ai *. iil ,
......... f '........
--I~~ JA *I
Igcanent by reasoh of deletions necessary to accomplish decla
w'.,< ::' ., :'.:
itb6nstitute authority for declassification of classified copies
y.bear the same title and authors.
.: .. .
Date of Manuscript:
of a similar document which
.. :e. *
<.l***.t m ,thi docun
.:a ^U C
ment consists of
May 14, 1947
xxx* : /
lx ll xx x
x x !M
:. #i x<
*' x .*x
F ~ x~s"x, ^L~xx, -: nil ^$&8 M flififi i
><;;li <> "
MAINTENANCE EXPERIENCE AND DEVELOPMENT
..The writer has
been working with
29',,1943, and has been maintaining the
'205"Aince that time. This report is desi
Us.;;/ : "
. tlie operation of the California Circuits,
W. rrifteahd members of Mr. English's g
group in building 706-A since November
California Circuits in the counting room of building
gned to give a genera
and report on some
roup have carried on.
I discussion of the operation of
experimental work that. the
Maintenance data is for the
:. period from 11
: *' ; iI
9/43 to 1/15/44.
CIRCUITS IN USE
The California circuits in Building 205 are composed of three
type A Beta circuits
: drawing 717-B-
..p.:tyi Alpha ci
.' :Eci' circuit i
*.. .. <
::* :. :> uf ** w:* -:* ** :.i ,
'1'. V -S'
a- ,Tr tircut c
:.: .. ..
;and a 605 inver
.4.* 1'f j .
ii -:" dit(since 11/29
,:: .:. .. ,: :.^.^ -. :
! ., tit, Lo which hai
12) using N
eher-Harper quenching for mica window G-M tubes and five
717-B-13) with type A amplifiers
type alpha chambers and two standard alpha chambers
is checked with a
are entered in th
used with the five
standard every shift and adjustment made if necessary.
e set log book and these complete records are available
r CIRCUIT (717-B-12)
consistss of an external Neher
-Harper quench tube (6J7G),
a 6SJ7 amplifier
No maintenance of any kind has been performed on this cir-
)/43 except for replacing G-M tubes,
d their windows broken.
four of which lost their plateau and
Experimental attempts to build the Neher-Harper tube into the set have failed to date
as the pulses obtained without modification of the input amplifier would not trip the scaler.
Work on this phase will be continued.
. 'Examination of the relative plateaus of an Eck Krebs G-M tube with resistance and Neher-
. Harper quenching was made.
ults obtained are included in Table 1 and show that
Sthe plateau was lengthened by a factor of between 2 and 3 by use of Neher-Harper quenching.
The difference in counts per minute shiownn thed ablle was dfe largif tb different geome-
try of the,
the writer understands that thie resolution of the Neher-Harper
circuit is slightly less than that of a resistar
The circuit used in the Type A Scaler (717
quenching without a preamplifier.
to give a pulse of the proper sign,
ice quenched circuit. "
-B-12) is unsuitable for use with resistance
A circuit consisting of two amplifier tubes is req
large enough totrip the sealer.
come in the experimental Beta Set (717-B-11) by using an input circuit
similar to the
replacing the second 6C5 wit a 6SJ7;
B. ALPHA CHAMBERS (DWg.
The electronic circuits of the magnet and standard alpha chambers are the same.
supply all voltages used.
Operating experience with these chambers has been rather unsatisfactory
It has been
necessary to replace the 38 tube at frequent iliterval. The criterion for replacement of
the tube is high hash level or low counting rate on the standard
ALPHA AMPLIFIER (Dwg. 717-B-14)
This amplifier is a three tube non-linear nohi-fed back amp
ing a D.
supply for the first tube.
The first and last tube are zero bias tubes and the gain control
is normally set so that the alpha pulses saturate the last tube.
As"would be expected from the design, the a lttiml# is
as to the tribes,
the first 6J7 being the most critical.
ating trouble has been experienced.
However, when tubes
have been selected
, little oper-
Only one 6J7 has been replaced in 205 building since
The gain plateau is usually quite long, varying from the point where the alpha pulses
, to the point where the hash counts.
Thd Very good signal to no
ise ratio en-
ables alphas to be counted over 5 x 106betas in a standard chamber
at 8% geometry>with a magnet chamber.
and over 10a betas
The feature: of saturating the outgpt tul e enable
sf the control chemists to judge very well
as to whether a sample can be counted.
The gain can be reduced only so far as
give saturated pulses and, if the hash is near the tripping height then,
the sample cannot
be codtted reliably. This enables an inexpbriencea operator to judge when he is getting
near the danger point" the picture is very elat othe oscillograph.
Critical circuit constants in this circuit are the
condenser and the screen dropping
This difficulty was over-
STROHMEYER PULSE SHARPENER (717-B-13)
This is a multivibrator
circuit which serves
sharp, even height pulses
have been confined to defective 6B8 tubes
A tube tester will not give a re
whether a tube is good for this
SE.: TRIODE SCALING STAGES (Dwg.
, 12, and 13)
Hi-:- :'. .~ Z 1inc
... to thu
S.% .i@."i". *
i^ ': !!,;.. ',,,
.: .. .. n-
.* .. *;. ..n
t.:' .:..: *:" $
i ..>:- ".f~ ".
.:;. :: .- .' ..
:'t *:".. ,.
S .. ;: b
: : ".
!.i : .
* l ." *
: ., J
B r"'- Th
i^ .';,:,.,*..JUl* Il _
:: .Bh a
I.... .. ha
," 1 .I.I
consist of a 6C5
with their grids cros
proven to be very reliable and ea
e scaling stages
interstate amplifier biased beyo
to the plates of the opposite tube
rvice, only five service calls du'
being encountered between November
were due to bad mica
:reset switch, or
e scaling stages
tive rectifier tu
nd cutoff and
. This circuit
e to failure to
, 1943 and January 13, 1944.
(bad on a condenser tester), one due to an
ne due to a shorted 6C5, and one due to defective 400,000 ohm resistors
. Since January 13, two failures have been encountered, both due to
bes. The characteristic of this failure is the same as that due to low
,e- the interstate amplifiers' fail to pass the
onstants were such that
the B+ with good rectifier tubes
ges on 12 operating sets were taken on January 1
Range of B+ voltage 330
it, it was found that the
barely high enough.
with the following
- 390 volts.
Range of interstate amplifier B- voltage
!.-ra e of
scaling pair grid return v
aRahge of conducting plate voltages
dRange of grid voltage
-35 to -40 volts.
oltage -69 to -'
50 to 180 volts.
-5.3 to 17.
':Maximum grid difference.
Regular set 9.4 volts.
. i .
Grid voltages taken by removing the scaling pair with all other tubes in.
ds data demonstrates that the scaling
stages are not critical
bound that the following voltages are of use in trouble shooting.
-35 to -40 volts; plate voltage of the conducting tube
as to voltages.
shouldd be under 100 volts.
Gridi tf- the not conducting tube should be at least -35 volts.
should be at least 350 volts.
The stages are not critical
as to tubes and any tube that checks al
right on a tube tester
failure of a
and BP5 tubes may be used interchangeably.
stage to scale does not necessarily block the set.
. .and;the 'interpolate meter does not give as good indication of trouble as
the neon lights
used with the Columbia circuit.
The triode scale of 64 (717-B-
neon lights for that
reason and because an interpolate meter cannot be used with a scale of 64.
Line voltage stability of the sets is good but the interpolate meters do not read correctly
when the line voltage is different from that at which the calibration potentiometers were
set. The only set that has been thoroughly investigated by the writer for surge stability is
hIa 4-v.r o aRA f1~1 n r D 11\ uk'snk 4nc e+nkla f.A On A_ irnr w:. ..n..-.lj. ...
- 4 -
supply of this
set differs from that
shown in the drawing imthat two rectifier windings and
were used to get the plus and minus voltages.
The output stage uses a 6C5 inverter amplifier and an 884 thyratron to drive
round case recorder. No trouble has been encountered with this circuit to date.
be noted, however, that this output stage will not drive a Wizard Counter.
G. HIGH VOLTAGE SUPPLY (717-B-12 and 13)
The high voltage supply uses a single 47 tube to regulate it. It is rather complicated to
stabilize two knobs on the front of the set and a test switch to throw resistance into the
supply to the high voltage transformer being manipulated to give good voltage stabilization.
Practically no load can be drawn from the supply,
the load of a G-M tube and Neher-Harper
circuit counting at a rate of 2000 counts/min. being enough to cause a distinct drop in
In addition, the Pyranol output condenser is very critical in alpha service,
sers good for all normal purposes allowing enough A;
C. ripply to pass through to upset
the alpha amplifier.
Maintenance on this part of the circuits has consisted of replacing defective dropping
resistors in one G-M set and two Pyranol condensers in alpha sets.
One G-M set has been rebuilt to use the high voltage circuit shown in drawing 717-B-16.
This high voltage was stable at 1000 V. outp
load, no meter deflection being, perceptible.
iut from 80 to 135 volts on the variac with no
It was stable in the same way at 1000 volts
when one milliampere was drawn from it at regular line voltage.
No hash was introduced
in the alpha sets by this high voltage and the beta set containing it is now in regular opera-
tion in 205 counting room.
after the initial warm up.
TRIODE SCALE OF 64 (Dwg.
No drift has been encountered in the high voltage of this set
A triode scale of 64 was builtaccording to the drawing 717-B
-11 except that two rectifier
windings and rectifiers were used for the plus and minus voltage supply.
When first built,
sufficient ventilation was not provided and trouble was experienced with change in the
400,000 ohm dropping resistors.
This trouble has been cured by drilling ventilation holes
in the top of the chassis.
The set was put into operation December 17,
1943 in the 105 Bldg.
counting room. No troubles within the set were. encountered until January 7
time the last two stagesstopped
scaling and the set started to blow fuses.
to the 6L6G which had 2 megohms between the grid and ground on fixed bias
'his was traced
. The dropping
resistor network was changed and the set put back into service.with nothing whatever being
done to the scaling stages.
.> ~* A .
Original tune-up of this set demonstrated the necessity for having the
able so that the
highest conducting plate was below 100 volts
Outside of that
, no unexpected
factors were encountered.
TRIODE SCALE OF 64
- GENERAL REMARKS
The set B+ must supply at least 80 milliamperes and the B-
supply 15 ma
use of 6SN7 tubes
instead of 6C5's
scaling pair would reduce the number of
.tubes required from 18 to-12 and make the layout
comparable to that of a Columbia Type
shown in the drawing provides a circuit that requires only one
rectifier and rectifier winding but requires a VR 90 to prevent the recorder current
upsetting the B minus.
If sets like this were manufactured in large quantities, it wou
400,000 ohm resistors plus perhaps 10% 100,000 ohm resistors
precautions need be taken.
Id be advisable to us
. Aside from that no
Use of a bus bar for B+ and B- voltages is
a maintenance viewpoint in that a poor joint to one stage
will not affect the operation of
Cf .= ."
IM". .E r ".
.:: ... .
Li ". .
!X! m a m
,si !!," ; .*.*
Voltage data on the existing
5 volts; B- to amplifiers -3
it pair out,
scale of 64 is as
and the maximum grid to
B- 410 volts
The grids range from 5
grid difference is 13
to 29 volts
to scaling pair
with tubes of
PERFORMANCE OF COUNTER G-9
S. *eSS***... CS *CCC*#* .;'.. m 9
a &.~. .
...... .. ..a .
...eI.... U .... ... .*..
.............C. ... C s t~ mt a
S C C .' C. a ., .'* a. ..m eas .. a a *.
.... 5* S5**~Cm.&t5*,SS**
.S. **.m .me...... ... t..I ISIC m*.***C ..**. .... ... ..*.. ** *S e*S t** ma e as ..* a
*.* i' Wta *I~ ~ .. al,, 9* ** 5* *5*,* *I. **t. 55Cm 54C CI*Cam *tm*l UCS aeiIII l 1I (s (IIIII .tI
.................. ..S... SC. .... ..........*.. ................ .... .... ... ..S..
ebSC***Ce**5**Sese eS**e**e*C**** Ct S**e*** *******m***a*.s.*******Se*t***SW**St
Cs...Ca .e*emme*m4* 4a ***t ma.*.* mS*S***0555**505am ***C****mm *** bes mm.. ests CCC CS Sm
*SC* SC S*SCCCS SC ** smS mS.em ** CC,*C** CC CCCC SC.tOSS S*C*.* ,t*S* 5*55 C*S.*C eS
The lengthening of plateau by means of Neher-Harper quenching is apparent.
..2 ..g ... .. .g ... .... .. x xx**** x x x
x x x 4 x x
UNIVERSITY OF FLORIDA
I111 116 II 111 I 11iilliII
S*3 1262 08909 7215
1:1. ^.. .. ...... __'
", ,,,E :
.'.1 .. ...
i::; i. *rhl l: :* i- "t &
...y. : *. .- .
.I:. *:: ::: **
.: *K! *! iii!X u" C ..::. '*X
,,,!,!!i!fll y*!"*fC !s
'* -* -* *: ::.:: a ***:
= j.'" Vj *j a ::M.AfI .;:
:,, ,: ha : :
4.. .. ......* :::**... .***..i
.:. *" iil ::-:a x "iiic:^t
.,,, .. I. .-
^ :.::* .~; *j8.: iS
*. *.i *
,, ,: *lI** -- 1 SS~
.: ",.:, !!!' ."l: E
.., : i* i i.
: I.: :
.* .. ** .. .. .. H i
*....' g .i : *.. .i .
,,, ,, r
.. : :: .
.*.. 1 i ,, .
*" X: i.s 'V sKs' .K" S: "'
........... .. . ...
.. :. ::* : ::p,: ,, .,,
,,,,, ,,ii is. ... i,
," i. f'c :** *" ."*:
".. .. .. .. .. .
j ., -; .:-- -~
,,* l ,,.:,
,,,, H;, ,,
.' .:ilal.:illi!*! I;"*g'
i ,ii ::*:* i... :.
......... ......n H H ,,.
,, ,,,,,,B ,,~j BJ "
*:. i.:m ':: ".. f
-.. ... ",
*. ^S *^:::* n. .** :.
.' .,.::: ::,,..,= '. .
,",::,:::,,, x,, AS e
-:* =:.!"!!VqA -:* q *
S : ...:!".. .. ...
.*,: ",::-:a. "" """ *.ii'"
*: .. I*.
: -*n E-. .: *M
., ii*: ::*,, i : "
*. Ci"** :S .:
ii n"..:in*: .......
., 1 .:, ,,
*"q ;* .. : *..
,,,:* .:,,*:, ,:::
.* : : ,: .
q.i l : ll: = --l
::i* :::: ** *:*.
.. .... .
.:* .:..*. i i.i:
.. .. .* 7. .
jjii: *i': iii~ e *
-* .*.."h* ........I .
'. :. "::iii= :r....:" i,,: .
.*n **..:i:: ..:* .* : :: :.**..
".. ,, -
**:*: E ii : **...:.""*". :i :.:1!
H. *.... :
,** ..:** .* ? *:**.....: .
,,...:"..*: .l :'.
: '. ......: =. ...
S*, ,:i ::" i i:,'* *:, :: ,.
...... . ...... *. ....... .
S ,x :... ... ; i
": ::p: .__"*::* .",i
**6 *H' *
=..ip i. ... --i
.. ~~.:..g*ijli :... .
.- ..N i.. .
:. *LH f.
: :. '....
i. .l "
":E*= ,, -:
S ...* .Z : ".
.. .ii*: '" .ur.
,.. ., *..' "" *.. *:
*. : r :F- ,
*' ,,, *.:"i.g "
.* *; ..gg .*,. ..
4** .*., *5 I