The Washington times., 1929-11-01
TAT. WILL USE
lNEW RADIO IN
LONG HOPS

RgEw YORK, Nov. 1.-The de.
Raiopment OF new radio trans
Rnltter for use aboard planes Of the
Transcontinental Air Transport,
ssLandbergh" coast-to.coast air-rail
aine, has been announced by J. v.
Magee, vice president and general
manager Of the system.
Tests OF the new transmitter
have been carried on in scheduled
0neration for the past two months
and the results are said to have
bean excellent.
The longest test made. according
70 Henry w. Conner. Eastern traf.
lie manager, provided Q clear two
way communication between
plane flying over the T. A. T. air
T.. "A. T. radio station at Clovis, N.
Mex, q distance Of SIT miles.
Eliminate Troubles
The new transmitter has been de-
Gigned to eliminate all the diff
culties which have been found in
commercial radio sets: 1t is an
! adoption Of we'll known radio cir
cults and principles and IL unique
chiefly for its small size, slight
weight and power radius. One OF
its unusual features 10 that 1t can
be installed in the tail Of the snip
rather than in the passenger
, cabin.
The weight of the transmitter
complete Including all controls ana
fuhes. dynanotor. antenna ana mic
rophone is 81 pounds. The trans
xnftter panel weighs only 30 pounds
with the four tubes in place. The
weight Of former equipment used
! hy the Il. A. r. was 1S5 pounds.
The fransmitter Is mounted on
Danel u inches by 81 inches and
consists of four tubes connected IN
q master oscillator-power amplifteF
} circuit of 100 watt output. An os-
eillator tube, power amplifier tupe
. and lfaoddlator tube each OF bV
watts and microphone tupe OF
rs watts are used.
Only five connections are used
20 the transmitter; two high voltage
CONNECTIONS from the dynamotor.
two ADtthe tube fi1aments from the
shipss battery and one to the micro
TheA tiynamotor, which has an
hltDllt az 1000 volts, and am
Oeres. takes its power from the IL
volt battery carried as regular
euuipment. A newly developed
' double voltage, engine driven gen.
orator will be installed shortly TO
D furnish the 1,000-volt supply direct
to the transmitter.
Trailing Antenna
A trailing wire antenna which
can be let down and taken up on
reel operated from the pilots cock
BIT IL used for the transmitter and
= . special type of fairlead insulates
the antenna from the metal skin
Of the ship, The antenna, when
down, Is weighed with As-pound
attachment streamlined to offer the
4 least wind resistance.
The microphone is Of the Army
type, redesigned for hand use.
= Operation of a single switch
throws the circuits. from. receiving
to transmission, starting the dyna.
motor and the tfansmitter and
sending current to. the tube fila
ments. The opposite throw of the
switch changes operations from
Transmission to receiver. !
The receiver has a modified SUI
perhetrodyne circuit with six tubes,
tIree Of which are Of the screen
grid type. The receiver is also To-
j. Gated in the tail of the ship and
y controlled remotely from the cock
pit. n five foot vertical antenna is
used receiving.
In aUe tiOn to normal transmits
sion Of messages from planes, the
- tranemitter is also used for direc-
tion finding. The ground operator,
> each time he is in communication
with a plane aloft, throws a. dual
loop antenna into the circuit and
determines the planes directional
bearing from his station. The pilot,
in each transmission, gives his
geographical location, thus afford
ing o double check Of the planes
position.