Heathkit DX-40 User Manual

There is considerable similarity betweenthe screws and nuts of the 3-48 and the 4-40 hardware
supplied. Before using these pieces, examine them closely to determine that you have the part
called for in the instructions. This is particularly true of the smali size 4-40 nuts which re-
semble 3-48 nuts in physical size. These nuts may even hold on a 3-48 screw, but will feel
loose. if any doubt exists, try the nut on a 4-40 screw tocheck it. There are only three of these
and they should be used in mounting the crystal sockets.
Inthe design of the Heathkit DX-40, no effort was spared to obtain the highest quality components
and assemble them in the best possible arrangement. By the same token, the kit builder should
exercise a great deal of care during assembly and wiring. Only by putting the best possible
workmanship into the kit, can best results be obtained from it. There is also a great deal of
personal satisfaction in a neat, professional-looking transmitter, resulting from careful assem-
bly. and wiring. A common factor of radio trequency instruments is the critical placement of
leads and components. The use of extensive bypassing and shielding inthe DX-40 has eliminated
a great deal of this. However, the lead dress shown in the pictorials and bottom chassis photo-
graph should be followed carefully.
During the assembly and wiring procedure, a rag or some soft material should be placed over
the work bench to prevent marring or scratching the chassis or component finish. Capacitors,
resistors and transformers usually have leads longer thannecessary to make the indicated con-
nections. In the interest of both efficiency and appearance, the leads should be cut to an appro-
priate length before the connections are made. In many cases, the specified wire lengths may
seem long. These lengths were chosen so the wire could be run close to the chassis and formed
for the best appearance.
Marking the letters of the tube sockets ana terminal strips on the chassis as they are installed
will be a great help during the wiring procedure. The actual tube markings may differ from the
type specified in the parts list by an additional suffix (A, B, GT, etc.). This denotes a minor
variation which will not affect the opetation of the completed instrument.
This manual is supplied to assist you in every way tocomplete the DX-40 with the least possible
chance forerror. We suggest that you take a few minutes now and read the entire manual, omit-
ting the step-by~step instructions, before any work is started. This will enable you to proceed
with the work much faster when construction is begun. The large fold-in pictorials are handy
to attach to the wall above your work space, Their use will greatly simplify the construction of
the kit. These diagrams are repeated in smaller form within the manual. We suggest that you
retain the manual in your files for future reference both in the use of the DX-40 and for its main-
tenance. During the initial testing of the transmitter, it will be out of its cabinet. REMEMBER
THAT VOLTAGES DANGEROUS TO LIFE ARE PRESENT AT PRACTICALLY ALL POINTS
ON THE CHASSIS.
NOTE: Sometimes the builder may find a place where it is difficult to hold a nyt for assembly.
Using long-nosed pliers, press a piece of solder across one side of the nut until the solder is
forced part way into the threads. This will hold the nut and furnish a narrow handle useful for
inserting the nut into tight places.
In
order
to
expedite
delivery
to
you,
we
are
occasionally
forced
to
make
minor
substitutions
of
parts.
Such
substitutions
are
carefully
checked
before
they
are
approved
and
the
parts
supplied
will
work
satisfactorily.
By
checking
the
parts
list
for
resistors,
for
example,
you
may
find
that
a
2KQ
resistor
has
been
supplied
in
place
of
a
2.2K
as
shown
in
the
parts
list.
These
changes
are self-evident
and
are
mentioned
here only
to
prevent
confusion
in
checking
the contents
of
your
kit.
We strongly
urge
that you
follow
the
wiring
and
parts
layout
shown
in
the manual.
The
position
of
wires
and
parts
is
extremely
critical
in
a
stable
transmitter
and
changes
may
ser-
iously
affect
the characteristics
of
the circuit.
Resistors
and
condensers
generally
havea
toler-
ance
rating
of
+10%
unless
otherwise
stated
in
the parts
list.
Therefore,
a
100
K® resistor
may
test anywhere
from
90
KQ
to 110
KQ.
The
letter
K
is
commonly
used to
designate
a
multiplier
of
1000.
Page 5

Heathkit DX-40 Specifications

General

Brand	Heathkit
Model	DX-40
Category	Transmitter
Language	English