Heathkit CT 1 Assembly Manual

Page 2

STANDARD (OlOR con: -

morons AND «muons

INASULATED FIRST RING _ SECOND RING THIRD RING
Axll [ID lis|sr°R UNINSULAIED BODY 00w END COM) DOT COIDII
"4 rule.- rim Figure Second Figure Multiplier DISC CERAMIC RIM <00!
IM- Ian-{Inland ' 5-0.: MM
BLACK 0 0 None
- snow»: ; § 00 1
RED .
ORANGE 3 3 .000 W
YELLOW 4 4 » 0.000 rum-u
GREEN 5 5 00,000
r... lléfm 3 3 0 $33
um i _ . .
Wircwc-lijfimnbmsufl w ' GRAY a , - 3 00,000,000 "w 0-1
I" m a M, m WHITE 9 9 000,000,000
mun run our nrsrsron 5-001 noun urn (rum: (Autumn Emma nus: K (mm "my
» mun ' ' """ [1-, ml. "'1"
u ",m mu.
' 4 I . m 1.1."...
r. . mm... , >_ "' F r: mum mum roI-mu
RADIAI. IIAD (IAID) RESISTOR IV-PASS COIIPIIIIG CEIAIAIC (APACITOI AXIAL AD CERAMIC CAPACITOR
. "I-Iridiu . '
u n...
r. "if 1st 0.... V

The 'standard color code provides all necessary information re-
quired to properly identify color coded resistors and capacitors.
Refer to the color code for numerical values and the zeroes or
multipliers assigned to the colors used. A fourth color band on
resistors determinestolerance rating as follows: Gold = 5%,
silver = 10%t Absence of the fourth band indicates a 20%
tolerance rating.

The physical size of carbon resistors 'is determined by their
wattage rating. Carbon resistors most commonly used in Health
kits are )6 watt. Higher wattage rated resistors when specified
are progressively larger in physical size. Small wire wound
resistors l/é watt, 1 or 2 watt may be color coded but the first
band will be double width.

MOIDED MICA TYPE CAPACITORS

CIIIIENI SIAIIDAIII CODE

INA MOT (OISOIETE) IIIITOII SILVER IAICA

s . ~ _ RATED 500 w.v.0.<. t m rot. ("Aaron
um. (um 1-:le """ ii: a.
um um W A Ilhlpllol mm
(hr CODE W
0 Mom mm
IIA (5-001 OISOIETI con!) IMA MOT (0.50mi) EMA HOT (OISOIET!)
In . Is"
slum-n r Vol-um
nil ww- um" :}§'lir-I rig-m mm- Mn.
".1
In lefiu-t 'i'm
Mu... var... i In, """"" m '
l i Z '75..." . mum... Tiler-a mum. v.0... "0 wiflr"
m...

MOIDED PAPER TYPE CAPACITORS

TIIIlIlAl CAPACITOR

n .
ghnlrllprl

m Wit-t
olfliVoh-uflum
AzmmmhMumn-mv.
mzmrbddlafnnuhn

MOLDED FIAT CAPACITOI
Co-onhl (Odo

unruly I
==r run-d hr My
, nu.

in. (out (Autumn
sum "'

Null-I Vol

-- um"

film-m

The tolerance rating of capuoiuirsjs determined by the color
code. For example: red = 2%, green = 37%. etc. The voltage
rating of capacitors is obtained by multiplying the color value
by 100. For example: orange = II x100 or 300 volts. Blue =
6 X 100 or 600 volts.

In the design of Heathkits. the hem pom ture coefficient of ceramic
or mica capaoitors is not generally a critical factor and there-
fore Heathkit manuals avoid reference to temperature welli-
cient specifications.

, an... .1 cum-m

Page 5

INTRODUCTION

The Heathkit model CT-l Capacitor Tester is an instrument which will disclose open or shorted
capacitors without removing them from the circuit. It is an extremely simple instrument, both
to construct and operate, but yet an instrument which should give many years of good service if
the assembly instructions are followed carefully. By not trying to "out-do" the manual to come
up with an exceptionally "pretty"wiring job, you should be able to plug it in, turn it on, and yell,
"Hey Ma, it works!"

An important note should be injected here: Route wiring according to the pictorial diagrams!
Due to the high frequencies encountered within the tester, lead length and placement is quite
critical, especially around the switch.

Only one tube is used, since it can be made to "double-in-brass". It functions as an oscillator,
an indicator, and it is self-rectifying.

A five-position switch is employed, which controls the powerto the instrument, selects the test
being made (i. e. , OPEN or SHORT), and also provides a check on the proper operation of the
tester continuously. A further explanation of the switch position functions will be found in the
OPERATING" section of the manual.

CIR CUIT DESCRIPTION

OPEN TEST: The triode section of the electron ray indicator tube, or "Magic Eye", is employed
as a conventional Hartley oscillator, but here convention ceases. Reference to the schematic
diagram will reveal a secondary" winding coupled to the oscillator coil, with the oscillator

tuned to about 19 megacycles. Now here's the catch! Coupling is "tight" enough to cause the
oscillator to quit oscillating! In this respect it can be compared to a Grid Dip Meter. As cou-
pling is increased, the absorbtive action of the coupled circuit sucks energy out of the oscillator
coil, lowering the strength of the oscillation to the point where the oscillator quits altogether.
Had enough oscillators for a while? Then let's proceed.

With no oscillation present, no bias is developed across the grid leak, resulting in maximum
current flow through the tube. Under these conditions, the eye is open to its widest angle. When
a capacitor which is not open (i. e. , good or shorted) is connected across the secondary, it be-
comes de-tuned sufficiently to allow the circuit to oscillate. Under these circumstances, bias
is developed which limits the current flow to a relatively low value, causing the eye to close.
In other words, if the capacitor has continuity, the eye closes. Simple, eh?

SHORT TEST: A biasing voltage, obtained from the power transformer, is fed through a cur-
rent limiting network to the grid of the tube. The test leads are connected between grid and
ground. A shorted capacitor will short out this bias voltage, opening the eye. One which is not
shorted has no effect, unless its reactance is extremely low. However, a reference is provided
to determine the effect of a shorted capacitor, and unless the capacitor has a reactance of less
than 10 $2 at a sixty-cycle frequency, the check is accurate. A further description of this ref-
erence can be found in the "OPERATING" section.

POWER SUPPLY: The power supply in this instrument consists of a power transformer only.
No rectifier is necessary, since the "eye" tube is self-rectifying! When the potential on the
plate is positive in respect to the cathode, current flows. When the voltage on the plate swings
negative on the other half of the cycle, no current flows, and the tube just "coasts. Since AC
is used on the plate and grid, proper phasing of the transformer windings is necessary.

ABOUT THE MANUAL

With the exception of the circuit description, this manual was written for a definitely non-tech-
nical minded individual. To you with a technical background, it may seem rather elementary to
have to follow a step-by-step procedure such as this manual incorporates. However, experience
with all types of instruction methods has shown the method used here to be the most foolproof
for both amateur and professional builders. The combination of pictures, diagrams and worded

Page 3

Page 21

WARRANTY

Heath Company warrants that for a period of three months irom the date of shipment, all Heathkit
parts shall be free of defects in materials and workmanship under normal use and service and
that in fulfillment of any breach of such warranty, Heath Company shall replace such defective
parts upon the return of the same to its factory. The foregoing warranty shall apply only to the
v ' original buyer, and is and shall be in lieu oi all other warranties, whether express or implied
1 and of all other obligations or liabilities on the part of Heath Company and in no event shall
Heath Company be liable for any anticipated profits, consequential damages, loss of time or other
losses incurred by the buyer in connection with the purchase, assembly or operation of Heathkits
or components thereof. No replacement shall be made of parts damaged by the buyer in the
course of handling or assembling Heathkit equipment.

NOTE: The foregoing warranty is completely void and we will not replace, repair or service
instruments or parts thereof in which acid core solder or paste fluxes have been used.

HEA TH COM PANY

All prices are subject to change without notice. The Heath Company reserves the right to dis-
continue instruments and to change specifications at any time without incurring any obligation
to incorporate new features in instruments previously sold.

Page 23

HELPFUL KIT BUILDING INFORMATION

Before attempt-mi actual kit construction read the construction
manual through t orcughly to familiarize yourself with the general
procedure. Note the relative location of ietA'irials and pi al inserts
in respect to the progress of the essernliiy proeedure outlined.

This information is offered primarily for the convenience. of novice
liit builders and will be of definite assistance to those lacking thorough
knowledge of good construction practices Even the advanced elec-
tronics enthusiast may benefit by a brief review of this material before
proceeding with kit construction. In the majority of uses. failure to
observe basic instruction fundamentals is responsible for inability to
obtain desired level of performance.

RECOMMENDED TOOLS

The successful construction of Hesthkits does not require the use of

cialized equipment and only basic tools are uired. A good quality
eectd'ic soldering iron is essential. The prefer size would be a 100
watt iron with a small tip. The use of long nose pliers and di nal or
side cuttingpliers is recommended. A smdl screw driver wil rovc
adequate an several additional assorted screw drivers will be he pful,
Be sure to obtain a good supply of men bore type radio solder. Never
use separate fluxes, paste or acid solder in electronic work

ASSEMBLY
In the actual mechanical assembly of components to the chassis and
be], it is Important that the procedure shown in the manual be care-
ully followed. Make sure that tube sockets are roperly mounted in
respect to keyway or pin numbering looutiun, ¥he same applies to
transformer mountings so that the correct transformer color coded
wires will be available at the proper chassis o ning.

Make it a standard practice to use look was srs under all 6412 and
8-32 nuts. The only exwption being in the use of solder lugs-the
nmly locking feature is already incorporated in the design of the
solder lugs. A control lock washer should always be used between the
control and the chassis to prevent undesirable rotation in the panel.
To improve instrument a pear-rice and to prevent possible panel
marring use a control flat nickel washer under each control nut.

When installi binding posts that require the use of fiber insulating
washers. it is practice to slip the shoulder washer over the bindi

t mounting stud before installin the mounting stud in the pane
ole provided. Next. install a flat figer washer and a solder lug under
the mounting nut. Be aura that the shoulder washer is properly
centered in the panel to prevent possible shorting of the binding post.

nwmary to expose more than a quarter inch of r

WIRING

When following wiring procedure make the leads as short and direct
at possible. In filament wiring requiring the use of a twisted pair of
wire: allow sufficient slack in the wiring that will permit the twisted
pair to be pushed a ainst the chassis as closely as pomible thereby
affording relative iso ation from adjacent parts and wiring.

When removing insulation from the end of hookup wire. it is seldom

e wire. Exressive

insulation removal ma cause a short circuit oondition in respect to
nearby wiring or terminals. in some instances, truusrormer leads of
solid copper will have a brown baked enamel coating. After the trans.

former

earls have been trimmed to a suitable length, it is necessary to

scrape the enamel mating in order to expose the bright copper wire
before making a terminal or soldered mnneetion.

In mounting parts such as resistors or condensers. triln off all excess
lead lengths so that the parts may be installed ill a direct pointrto~
point manner. When necessary use spaghe or insulated sleeving over

exposed wires that might short to nearby w in .
t urgently recommended that the wir

ress and parts layout

3
as shown in the mrntruetiou manual be faithfully followed. in every
instance. the desirability or this arrangement was arefully determined
through the construction of a series or laboratory models

SOLDER INC

Much of the perrormauoe of the hit instrumeui. particularly in respect
to aceurac and stability, depends upon the degree of workmanship
used in ma ing soldered connections. Proper soldered connections are
not at all difficult to make but it would be advisable to observe a few
before a connection is to be soldnrvd. the

precautions. First oi all

connection itself should be clean and mechanically strong. on not
depend on solder alone to hold a connection together, The tip of the
anlderin irnri should be hr' ht. clean and free of excess solder. use

enough cat to thoroughly

ow the solder smoothly into the j lit.

Avoid excessive use of solder and do not allow a flux floodii condition
to ooeur which could conceivably cause a leakage pat between
adjacent terminals on switch assembliu and tube sockets. This is
particularly important in instruments such as the V'lVM. (-srillr»
scope and generator kits. Emotive heat will also burn ur damage. the
insulating material used in the manufacture of switch assemblies.
Be sure to use only good quality rosin core radio type solder,

intense 1? um... i lair-Marlo
G'Wl' Gall-ml W m '5 "ID-conductor
minor Illuminating
[E w W ® sh
Swildi
Gmnd atiiiiar Variable 4M- Singla pol. rur-
-L- o'\o 0m
Switch
tndemr . \O r I t '
rmuhemmr double pole 0 . "u " I]
Gonnral 3 §{- fin. WW 0 \0 Crystal _l l-
" WI Switeh .
rraudemr 3 g Yharmimn M Triple pale 8:2 8 loco - K
Cramral cevblothra-r 0% O
Adiumbls ;; my Swish 1
Mdmd in" H m mam" O--v Multlpeint nr Cc); lmpco : M
Car. .r rotary 00
mgr-«1r clll lorir 0-v
Variable Conrail-lg gig «hm rendvrrur O-J swl" :Cq °"" = fl
Iron Cora Wiru .
Tmnitarraar ENE eonnamd J- JT + "M" *- errafarad = M F
Wiru
Cup-«her . Mi .
Cronin. inn Mirrupheu. :G , _
do mm + Mme-MW

Pam + AJnm' O Trrkulnrbuymlsol Plala a. in -O-
Electrolytit -l e V.Vellrnetar new-rm I'arariaalilrip-
G', . GM Kraaa 4
capacitor aawlhamnmr WW"! '7 l ¢ t t
Variabl- % uA. Mlaracrnmr,uer mhadc "i "0 9 X V X V X
lain-M MM 4 V

wary of Ll.£