Eddystone Short Wave Manual page 26

24
EDDYSTONE SHORT WAVE MANUAL
5 VALVE SHORT WAVE
SUPER -HETERODYNE RECEIVER
BATTERY MODEL - 13.6 TO 87 METRES
In response to an increasing demand for a
reliable and up-to-date short wave Super
-
Heterodyne Receiver for home construction,
this set is the answer. It adequately deals
with the existing problem of selectivity and
its appeal is further enhanced by the incor-
poration
of
effective automatic
volume
control.
The design of a short wave super -hetero-
dyne receiver presents some
difficulty for
home construction
since
it must not
be
too complicated to build or too difficult to
gang and adjust the intermediate frequency
stages without elaborate equipment.
This receiver admirably
fulfils
such
conditions and has a consistently good and
proved all round performance. It is simple
to construct, easy in adjustment, and the
short wave range can be extended by the use
of additional coils for the broadcast waves.
By way of avoiding complications an
H.F. stage has been omitted in the receiver
itself but if afterwards it is wished to take
advantage of the benefit from an H.F. stage,
the H.F. Amplifier, described on page 34 is
quite suitable for this purpose.
To achieve
best
results from the
set,
some previous constructional radio knowledge
is required. For the absolute beginner the
more simple
" Everyman Shortwaver"
is
advised (see pages 8 to 11).
CONSTRUCTION.
The views of top and underside of chassis
show layout of parts, and the point to point
wiring is easy to follow.
PROCEED TO BUILD AS FOLLOWS :
Scrape paint from chassis for all earth
connections
(see
wiring plan).
Fit
valve -
holders and terminal strips by using 6BA
screws and nuts provided. A 6BA soldering
tag is fitted under the nuts on each of the lower
right-hand screws, fixing the terminal strips
in position.
These are to anchor the stout
(16 gauge) wire which runs along back of set,
and left-hand side, finally going down to
point " E " on coil. This wire should be
placed approximately 21- from underside of
chassis.
Next fit the 1 mfd. condenser making
sure paint is removed from chassis to provide
good contact with case of condenser. A 16
gauge wire should be taken horizontally from
this condenser and bent down vertically over
V5, connection being made to centre pin. This
lead should be about 21s" above chassis. The
advantage of putting in these wires first
is
that one end of most of the resistances and
condensers is attached to one of them, thus
simplifying assembly.
Then fit and wire in
position
the intermediate frequency trans-
formers, noting that the metal braid on leads
is well earthed to chassis. The remainder of
the components can then be fitted, and wiring
continued, as shown on wiring plan.