Converter - Eddystone Short Wave Manual

38
EDDYSTONE SHORT WAVE MANUAL
ONE VALVE SHORT WAVE H.F. AMPLIFIER-continued
receiver ;
then the two sets of controls should
be worked in step. As before mentioned, the
50,000 ohm potentiometer control is used for
regeneration.
OPERATION AS SHORT WAVE
CONVERTER.
In this case the existing broadcast receiver
should be tuned to a silent part of the wave-
band above 1,000 metres. The converter unit
is then made to oscillate by the potentiometer
control, and the whole of the tuning is carried
out on the controls of the converter unit. The
actual wave range at tbe station that is received
will he that at which the unit itself is function-
ing.
A.C. MODEL.
The use and application of the battery
unit described, covers the A.C. model in full.
The circuit is slightly modified to take an
A.C. valve.
It will be noted, however, that the
A.C.
unit incorporates a filament
heating
transformer and no H.T. supply. This is done
because the necessary
rectifier
valve and
consequent smoothing and transformer ar-
rangements are unnecessarily expensive when
H.T. supply sufficient for the one valve in use
can easily be obtained from the broadcast
receiver. The H.T. lead on the unit should be
taken to a point on -the receiver where a
voltage of 120-150 volts is obtainable.
A
convenient point of tapping is usually at the
speaker or output valve of the main receiver.
TANK
AERIAL
/0
I 50
THEORETICAL
EDDYSTONE PARTS.
A.C. Model.
Price
1 Tank Condenser with Knob and Graduated
Dial Plate, Cat. No. 1042
..
6/-
1 Bandspread Condenser Unit with Slow
Motion
Head, Knob,
Dial and
Cursor, Cat. No. 1043 ..
6/6
1 Screened H.F. Choke, Cat. No. 982
5/-
1
Pointer Knob and Dial, Cat. No. 1044
1/-
1
Base, 6 -pin, Cat. No. 964
..
1/3
1
Valveholder, 7 -pin, Cat. No. 985
1/4
1
Filament Transformer, 220/240 volts, A.C.
10/6
I
Aluminium Die -Cast Chassis, drillid
all
necessary holes, finished inside ar_d
out battleship grey cellulose,
Cat.
No. 1057
12/9
2 Terminal Panels, drilled, with Plugs and
Sockets at 9d. each complete ..
1/6
1 Metal Panel,
finished
dark Crystalline
Brown, Cat. No. 1058 ..
9/9
1
Set Special 6 -pin Coils, Cat. No. 1065, Set
of 3 coils ..
12/-
1
Metal Cabinet, finished Dark Crystalline
Brown, Cat. No. 1061 ..
9/6
Total, L3 les. Id.
MISCELLANEOUS PARTS.
3 T.C.C.
.1
mfd. Tubular Condensers with
wire ends
..
1 Dubilier .0001 mfd. Condenser, type 670
2 Dubilier .002 mfd. Condensers, type 670
1
Dubilier 150 ohm 1 watt Resistor ..
1
Erie 50,000 ohm Potentiometer
..
1 Erie 20,000 ohm 1 watt Resistor
..
1
3 point On -Off Switch
..
24 i" x 6BA R.H. Screws and Nuts ..
4 yards 3 mm. Rubber Flexible Wire
1 Anode Clip (Clix)
2 yards 18 gauge tinned Copper Wire, Solder-
ing Tags, Washers, etc.
..
Total Price, approx. 18s. 6d.
VALVE.
1 Mullard SP4B Metallised, 7 -pin, or
Mazda AC/52 PEN. Metallised, 7 -pin
1.
Fin. a Cat
No.982.
II -
.0001/44.
111)02faii.
20,000.n.
H T-1-
INPUT TO
RECEIVER.
50,0001E
I
T41.
J.
A. 230V.
CIRCUIT DIAGRAM FOR A.C. UNIT.
1216