Eddystone Short Wave Manual page 32

30
EDDYSTONE SHORT WAVE MANUAL
ULTRA SHORT WAVE RADIO TELEPHONE-continued
The detector valveholder at the back -
centre, the interchangeable coil units and the
aerial and earth terminals are raised up on
pillars. The valve on the right-hand side near
the panel is the " quench " valve, and on the
left is the low -frequency amplifier.
Grid terminals on the valveholders should
point to the right-hand side of the receiver
when viewed from the rear.
The pre-set condenser which
is
also
mounted on small pillars underneath the tuning
condenser, is set to a capacity so that correct
controlof the detector oscillations can be carried
out with the 50,000.Ohm potentiometer.
The
high frequency chokes should be mounted
vertical so that their turns are at right -angles
to the tuning coils. The tuning condenser is
mounted by means of an adjustable bracket
and is faStened to the slow-motion head control
by means of a flexible coupler.
The quench and detector oscillator valves
are Osram or Mazda HL2, and the output
valves Osram LP2 or Mazda P220, which
need three volts grid bias with 120 volts H.T.
or if a pentode output is desired, a Mazda
Pen.220 may be used with 41 volts grid bias.
The frequency range of the set can be
extended from 4.8 metres to 12.4 metres, since
interchangeable coils are fitted. Each of the
three coils for a particular wave band consists
of the same number of turns, and the wave
range of the different coils is as follows :
3 -turn
4 -turn
5 -turn
6 -turn
8 -turn
coils.
coils.
coils.
coils.
coils.
4.8
to 6.35 metres
5.65 to
7.4 metres
6.62 to 8.72 metres
7.55 to
9.8
metres
9.5 to 12.4
metres
The receiver having been finished and
checked, it can be put into service.
Insert
valves, connect
high,
low tension
and
grid bias battery, which should be 120 volts,
2 volts, and 3 to 41 volts respectively. Insert
suitable coils as shown in Coil Table.
Set
tuning dial at " zero." Turn left-hand control
knob (quench) to minimum setting,
anti-
clockwise. To set
reaction, the pre-set
condenser should be screwed well out. Turn
right-hand control knob about one-third on.
Screw pre-set condenser down until receiver
just oscillates. Then check by turning knob
anti -clockwise when oscillation should cease.
By turning clockwise oscillation should take
place again. To check "quench" keep receiver
oscillating and advance quench control knob
until receiver stops oscillating.
The right-
hand knob can then be advanced slightly
until receiver is coming into oscillation again.
Repeat
by turning
left-hand knob
until
LIST OF PARTS.
EDDYSTONE
1 Microdenser, Cat. No. 900/20
1 Slow Motion Driving Head, Cat. No. 1036
1
Flexible Coupler, Cat. No. 1009
1 Adjustable Insulated Bracket, Cat. No. 1007
2 Frequentite Valveholders, 4 -pin, Cat. No.
949, at 1/5 each ..
1
Frequentite Valveholder, 5 -pin, Cat. No.
950
1 Quench Coil Unit, Cat. No. 958
2 Ultra Short Wave H.F. Chokes, Cat. No.
1011, at 1/3 each
..
3 Insulating Pillars, 2r, Cat. No. 1028, at
6d. each
6 Insulating Pillars, 1r, Cat. No. 1029, at
41d. each
..
1
Frequentite Terminal Saddle, Cat. No. 1046
3 U.S.W.
Coil
Bases, Cat. No.
1051,
at
1/- each
..
1 Set of 3 turn U.S.W. Coils, Cat. No. 1050
2 Black Knobs, r hole, Cat. No. 903, at 6d.
each
..
.
.
Total, 1 16s. Cd., plus Coils extra as required.
MISCELLANEOUS
1 Ferranti A.F.4 Transformer
2 Reliance 50,000 ohm Potentiometers
..
2 T.C.C. 0.1 mfd. Tubular Condensers (Wire
Ends type)
..
1 Cyldon 70-140 Trimmer
..
1
3 -point On -Off Switch
..
1 Dubilier .006, Type 670
..
1
Dubilier .001, Type 670
..
2 Dubilier .0001, Type 670
..
1 41 volt G.B. Battery and Clip
..
1 Erie 10,000 ohms 1 watt Resistor
1
Erie 1 megohm 1 watt Resistor
1 Erie .25 megohm 1 watt Resistor
.
1 Erie .25 megohm watt Resistor
1
Erie 3 megohm 1 watt Resistor
4 yards 4 -way Cable ..
2 Red Wander Plugs
2 Black Wander Plugs
1 Red Spade Terminal
1 Black Spade Terminal
..
2 Insulated Terminals
1
Panel, 9r x
x -V, Ebonite or Bakelite
1
Baseboard, 91" x 7r, r Plywood ..
1 Wood Strip, 7r xr xr
.
30 r x 4 R.H. Wood Screws
6 r x 4 R.H. Wood Screws ..
3 r x 6BA R.H. Screws
..
6 r x 6BA R.H. Screws
..
Approx. Total Cost, £2 10s. Od.
VALVES.
2 Mazda HL2 Valves, Metallised, at 4/9 each
1 Mazda P220 Valve
Approx. Total Cost, 5 Is. 6d.
Price
3/9
4/6
1/8
1/6
2/10
1/8
4/6
2/8
1/6
2/3
1/0
3/0
4/6
1/0
6/-