The All World Two - Eddystone Short Wave Manual

2
EDDYSTONE SHORT WAVE MANUAL
THE ALL WORLD TWO
15.5
TO
52
METRES.
A POWERFUL 2 VALVE SHORT WAVE BATTERY RECEIVER
WITH BANDSPREAD TUNING.
The set has a smart
front appearance ----
The Eddystone All World Two receiver
is designed to give adequate world wide head-
phone reception with a minimum expenditure.
It is the outcome of considerable research in
our laboratory and during extensive
tests
results were highly satisfactory ;
America,
Australia and other long distant stations being
consistently received with good volume and
quality.
The set is inexpensive and easy to build ;
simple to
operate and has
small current
consumption.
It is equally suitable for short
wave broadcast or amateur band reception
since it is fitted with the special Eddystone
Bandspread Tuning unit, which allows contin-
uous bandspreading on all wavebands.
The
waverange covered by the two coils supplied
with the receiver is 15 to 52 metres, but if it is
wished to
receive
on
intermediate bands
between 50 and 200 metres, extra coils are
available and no structural or wiring alterations
necessary.
There is a high degree of sensitivity com-
bined with low noise level, and careful design
of
the
aerial input
circuit
has completely
eliminated tuning blind spots. Constant and
smooth reaction has negligible effect on tuning
and complete stability of handling is assured.
A rigid die-cast chassis houses the component
parts and provides ample screening.
The theoretical circuit embodies a screened
H.F. Pentode valve followed by an audio
stage which can use either triode or pentode
valve as desired. The aerial input circuit,
although simple in design, was only satis-
factorily developed after protracted experi-
ments on many different
types
of
aerials.
It ensures complete freedom from tuning
blind spots, thus saving the extra cost of an
H.F. stage which is the generally accepted
medium for overcoming such trouble.
Re-
generation is obtained by a modified Reinartz
circuit, feedback current being controlled by
varying the S.G. voltage with a potentiometer.
The high tension battery is suitably isolated
to
prevent current leakage through
the
potential divider circuit.
CONSTRUCTION.
Proceed as follows :
The sockets for the aerial and earth and
'phone strips should be mounted and the strips
finally screwed on the back of the chassis by
the
" 6BA roundhead screws provided.
All holes in the chassis marked " E " on
the practical wiring diagram must be carefully
scraped above and below the chassis as earth
connections are made at these points.
Mount the 1+1 mfd. condenser on the
front of the chassis with countersunk screws,
and fix the two valveholders and coil base in
position.
Do not forget the soldering tags "E"
under some of the fixing screws.
The reaction trimmer is now mounted in
its appropriate
fixing holes.
The reaction
potentiometer, on -off switch and tank con-
denser should be assembled on the chassis,
the panel and 0-10 scales fitted, and the panel
held in position by the switch, condenser and
potentiometer fixing nuts.
To ensure absolutely noiseless
reaction
control the specified variable potentiometer
should be used.
and a tidy,
attractive chassis lay out.