Eddystone Short Wave Manual page 34

32
EDDYSTONE SHORT WAVE MANUAL
ULTRA SHORT WAVE RADIO TELEP HONE-continued
TRANSMITTER LAY OUT.
Viewing
photograph,
the microphone
transformer is shown on right, and driver
.
transformer on left, nearest panel. On the right -
rear of baseboard is output transformer. The
oscillator valve is furthest from panel and is
mounted on insulating pillars. The Class B
valve is on left between driver and output
transformer.
Driver valve is nearest panel.
The baseboard is raised on battens to allow
underneath
wiring to battery cable and
filament leads. In front of the oscillator valve
mounted on adjustable bracket is the variable
condenser, of 20 m.mld. capacity. Above the
condenser are the transmitting coils.
CONSTRUCTION OF COILS.
The plate coil is made from 20 gauge -A-ff
outside diameter copper tube. The inside
diameter of the coil is 2" and has 21 turns, a
tapping being taken from the electrical centre
to secondary of output transformer. The ends
are flattened and drilled 6BA so they may be
slipped over terminals
of
microdenser to
facilitate wiring. The grid coil consists of
light gauge rubber covered flexible wire and
is worked through the inside of the plate coil
tube,
the ends and also centre tap being
brought out through holes drilled in walls of
copper tube. The aerial coupling consists of
one turn ir diameter, and is made from
12 gauge copper wire with a systoflex covering
for insulation .This coil is mounted on a terminal
saddle, which is raised from the baseboard on
pillars and provides anchorage for the feeder
line to the aerial.
THE AERIAL.
Most of the conventional types of ultra
short wave aerials can be used with the
transmitter as described. These include the
2 -wire matched impedance or the Zepp fed
Hertz aerials, the only necessity is to have a
suitable coupling line between the output
coupling coil and the aerial. Full information
about U.S.W. aerials has already been pub-
lished in the Eddystone Ultra S.W. Guide.
The aerial itself, which for the amateur
5 metre wavebands needs to be one length
between 8 feet and 8 feet 6 inches long.
The
Eddystone telescopic aerial No. 1038 makes
an
excellent
radiator and is easily erected
anywhere, while portable if required.
LIST OF PARTS
TRANSMITTER
EDDYSTONE.
Price
1 Microdenser, Cat. No. 900/20
.
3/9
1 Universal Valveholder, 4 -pin, Cat. No. 1015
1/3
2 Universal Short Wave Valveholders, 7 -pin,
at 1/8 each ..
.. ..
..
3/4
1 Extension Control Outfit, Cat. No. 1008..
1/3
1 Adjustable Insulated Bracket, Cat. No. 1007
1/6
1
Frequentite Terminal Saddle, Cat. No. 1046
1/0
1 Pointer Knob and Dial, Cat. No. 1027 ..
l /3
4 Insulating Pillars, 2f", Cat. No. 1028, at
6d. each
..
.. .. .. 91)
Total, 15s. 4d.
MISCELLANEOUS.
1 Parmeco Microphone Transformer, Type
MT2
1 Parmeco Driver Transformer, Type D2A..
1 Parmeco Output, Type 02B
..
1 Dubilier .006, Type 670 ..
1 Dubilier, .0003, Type 670
1 Erie 5,000 ohms 1 watt
..
2 Terminals
..
1} yards of 4 -way Cable
4 Wander Plugs
2 Spade Terminals
..
1
3 -point On -Off Switch
..
1 4} volt G.B. Battery and Clip ..
1 16" length 3/16th Copper Tube
..
1 Panel, 9r x
x
" Ebonite or Bakelite
r
1 Baseboard, 9x 7y, r Plywood
1 Wood Strip, 7rx f# x }"
. .
2 or 3 yards Connecting Wire
4 1" x 6BA R.H. Screws
..
2 rx 4 R.H. Wood Screws ..
2 r x 6BA Screws and Nuts
Approx. Cost Miscellaneous Parts, 2 12 6
VALVES.
2 B.21 Valves, 7 -pin, Osram, at 11/- each
1 P220, Mazda
..
6/.
Approx. Total Cost, including Valves, £4 16 0