Heathkit SG-8 Assembly And Operation Manual page 23

HELPFUL KIT BUILDING INFORMATION
Neon Bulb
+
Loop
Battery
Fuse
Ground
C P
Resistor Variable
o
Potentiometer
4-
K
Thermistor 1000 =
O
Speaker
OHM =
O
Rectifier
+
MMF
Microphone
Plate
Typical tube symbol
screen
cathode
ilament
Inductor
General
Capacitor
General
Iron Core
Transformer
Capacitor
Electrolytic
Magnetic Core
Variable Coupling
ir core
Transformer
General
Wires
Crossing but
not connected
Wires
connected
Jack
two conductor
Jack
three conductor
Resistor
General
Resistor
Tapped
suppressor
Grid
Micro
Microfarad
Receptacle
two-conductor
Piezoelectric
Crystal
Capacitor
Variable
djustable
Powdered Iron
Core
ntenna
General
. mmeter
V. Voltmeter
G. Galvanometer
M . Milliammeter
u . Microammeter, etc.
Switch
Triple pole
Double throw
Illuminating
Lamp
Switch
Single pole
Single throw
Switch
double pole
single throw
1,000,000 = M
Before attempting actual kit construction read the construction
manual through thoroughly to familiarize yourself with the general
procedure. Note the relative location of pictorials and pictorial inserts
in respect to* Lite progress of t»He &sseml)ly procedure outlined.
This information is offered primarily for the convenience of novice
kit 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 cases, failure to
observe basic instruction fundamentals is responsible for inability to
obtain desired level of performance.
RECOMMENDED TOOLS
The successful construction of Heathkits does not require the use of
specialized equipment and only basic tools are required. A good quality
electric soldering iron is essential. The preferred size would be a 100
watt iron with a small tip. The use of long nose pliers and diagonal or
side cutting pliers is recommended. A small screw driver will prove
adequate and several additional assorted screw drivers will be helpful.
Be sure to obtain a good supply of rosin core 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
panel, it is important that the procedure shown in the manual be care ­
fully followed. Make sure that tube sockets are properly mounted in
respect to keyway or pin numbering location. The same applies to
transformer mountings so that the correct transformer color coded
wires will be available at the proper chassis opening.
Make it a standard practice to use lock washers under all 6-32 and
8-32 nuts. The only exception being in the use of solder lugs — the
necessary 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 appearance and to prevent possible panel
marring use a control flat nickel washer under each control nut.
When installing binding posts that require the use of fiber insulating
washers, it is good practice to slip the shoulder washer over the binding
post mounting stud before installing the mounting stud in the panel
hole provided. Next, install a flat fiber washer and a solder lug under
the mounting nut. Be sure that the shoulder washer is properly
centered in the panel to prevent possible shorting of the binding post.
Microfarad =
MF
oA°
o
o o
oro o
ox> o
7P0
o o
o°
WIKING
When following wiring procedure make the leads as short and direct
as possible. In filament wiring requiring the use of a twisted pair of
wires allow sufficient slack in the wiring that will permit the twisted
pair to be pushed against the chassis as closely as possible thereby
affording relative isolation from adjacent parts and wiring.
When removing insulation from the end of hookup wire, it is seldom
necessary to expose more than a quarter inch of the wire. Excessive
insulation removal may cause a short circuit condition in respect to
nearby wiring or terminals. In some instances, transformer leads of
solid copper will have a brown baked enamel coating. After the trans ­
former leads have been trimmed to a suitable length, it is necessary to
scrape the enamel coaling in order to expose the bright copper wire
before making a terminal or soldered connection.
In mounting parts such as resistors or condensers, trim of! all excess
lead lengths so that the parts may be installed in a direct point-to-
point manner. When necessary use spaghetti or insulated sleeving over
exposed wires that might short to nearby wiring.
It is urgently recommended that the wiring dress and parts layout
as shown in the construction manual be faithfully followed. In every
instance, the desirability of this arrangement was carefully determined
through the construction of a scries of laboratory models.
SOLDERING
Much of the performance of the kit instrument, particularly in respect
to accuracy and stability, depends upon the degree of workmanship
used in making soldered connections. Proper soldered connections are
not at all difficult to make but it would be advisable to observe a few
precautions. First of all before a connection is to be soldered, the
connection itself should be clean and mechanically strong. Do not
depend on solder alone to hold a connection together. The tip of the
soldering iron should be bright, clean and free of excess solder. Use
enough heat to thoroughly flow the solder smoothly into the joint.
Avoid excessive use of solder and do not allow a flux flooding condition
to occur which could conceivably cause a leakage path between
adjacent terminals on switch assemblies and tube sockets. This is
particularly important in instruments such as the VTVM, oscillo ­
scope and generator kits. Excessive heat will also burn or damage the
insulating material used in the manufacture of switch assemblies.
Be sure to use only good quality rosin core radio type solder.
Binding post
T.rminal .Irip fc (j Q Q j
Wiring between
U 4,71
like letters is — > x Y X Y X
understood
->
y
Courfeiy of I. R. E.
Switch
Multipoint or
Rotary