Eddystone Short Wave Manual page 18

16
EDDYSTONE SHORT WAVE MANUAL
5 VALVE A.C. S.W. SUPER -HETERODYNE RECEIVER-continued.
resistors should be soldered to the special
bakelite panel ptovided, this being mounted
from chassis on 2" pillars. When set has been
assembled, refer to lay out plan and circuit
diagram to continue assembly and wiring.
It will be noticed that one end of the
.1 mfd. tubular condensers is marked " outside
foil " and this end must he connected to
earth.
The power supply unit is separate from
the set and is made by Messrs. Parmeko
Ltd., of Leicester., 1 t is suitable for inputs
from 100 to 250 volts' A.C. 40/60 cycles. Its
output is 250 volts 40 milliamps for H.T.,
and 4 volts 5 amps. for L.T. winding.
The
rectifier valve is an Osram U10. The price
of the complete unit is £4 2s. 6d.
Parmeko
Cat. No. R116.
CONTROLS.
Taking front view facing set and working
from left
to right they are as follows :-
Volume control, tone control, tuning
dial
which has a dual ratio of 22 : 1 and 115: 1,
local/distance switch (clockwise for reception
of local stations and anti -clockwise for distance
reception).
Finally, at the right hand end of
the set is the tuner trimming control.
CONNECTING UP.
The 4 -way cable should be connected to
terminal block on power unit as marked on
wiring plan
B.
Attach aerial,
earth and
speaker, and the set
is ready
for
trial.
Although the intermediate frequency trans-
formers are adjusted when leaving the Works,
a
slight re -adjustment may be
necessary,
owing to small variations in valves and circuit
capacities. This is done by tuning in a station
at low volume, and adjusting the sunken
trimmer screws at the top of each I.F. trans-
former until the signal comes to maximum
strength. The following sequence should be
used --No. 2, No. 1, No. 3.
Greater ease and accuracy of trimming is
obtained if a 465 K/c oscillator is available.
A simple and cheap oscillator for this
purpose and its application is described on
page 20.
The set has been designed to use with
ordinary or doublet aerial. If the former is
used it. will be necessary to connect one of the
aerial sockets to earth as shown in adjoining
sketch.
COILS.
The standard kit of coils, Cat. No. 1065,
comprises 3 pairs of coils tuning as follows :-
Blue Spot pair, 15.3 to 25.5 metres.
Yellow Spot pair, 23.25 to 46 metres.
Red Spot pair, 41.8 to 87.8 metres.
Additional coils for higher wavelengths
arc available as follows :-
Cat. No. 1065W. White Spot pair, 85.8
to 182.5 metres, at
Cat. No. 1065P. Pink Spot pair, 160 to
354 metres, at
Cat No. 1065G. Green Spot pair, 250
to 560 metres, at
..
Cat. No. 1065GY. Grey Spot pair, 1,080
to 2,100 metres, at
7!6 per pair
8/6 per pair
8/6 per pair
10/6 per pair
The aerial coil in each pair is distinguished
by two coloured spots and is fitted in the
coil holder on the right hand side of the set
when viewed from the front. The oscillator
coil, which in each pair is marked with three
coloured spots, is placed in the left hand coil
holder.
AERIAL
EARTH
PICK VP
+
-
Top View of Chassis showing layout of Parts and Connections.