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TM 11-6660-204-25
operate the recording portion of the equipment.
g. Frequency-Time Recorder. The frequency-
The phase of the error voltage referred to the
time recorder is an electromechanical device
powerline phase is dependent on the polarity of
which in effect makes a continuous printed record
of the pulse recurrence frequency of the signals
the unbalance between the two dc voltages.
received from the radiosonde receiver. The chart
d. Measuring Circuit.. The measuring circuit
motor continually advances the chart under the
contained in the control panel consists of an ar-
recorder pen at the rate of l/2-inch per minute (1/2
rangement of resistors and potentiometers to de-
or 1 inch per minute in Frequency-Time Record-
velop and control the voltage across the slide-wire
ers RD88A/TMQ5 and RD-88B/TMQ5, and
potentiometer which is mounted on the frequen-
1, or 2 inches per minute in Frequency-Time
cy-time recorder chassis. A test voltage is also
Recorders RD-88C/TMQ-5, so the received data
developed in the measuring circuit and is used to
are spaced along the chart from the beginning to
check the operation of the recorder.
the end of each radiosonde flight.
e. Servoamplifier. The servoamplifier system
h. Power Supply. The power supply contains
consists of five voltage amplifiers and a line volt-
circuits that supply the voltages used to operate
age compensating tube in the converter-amplifier
the recorder and its associated circuits. It com-
chassis, together with two power amplifier tubes
prises one common power transformer which fur-
located in the power supply. The 60-cycle error
nishes an unregulated voltage for the balancing
voltage from the detector is amplified in these
motor circuit, a positive supply voltage, and a
stages, and is then used to drive the balancing
negative supply voltage together with regulator
motor in the frequency-time recorder chassis and
circuits to maintain these dc voltages at a steady
to actuate the pen-lifting circuit in the power sup-
potential. Power supply also contains the servo-
ply chassis. The pen-lifter circuit operates a sole-
power amplifier tubes, the pen-lifter circuit and
noid which is mechanically coupled to the pen car-
tubes, and the solenoid relay.
riage of the recorder. When power is applied to
i. Functional Operation. In considering the
the solenoid, the pen is lowered onto the chart. It
is raised from the chart whenever an error volt-
functioning of the recorder throughout the follow-
age exists, so the chart is not marked while the
ing detailed circuit analysis, bear in mind that
pen is being moved to the proper position.
basically the signal converter contains the wave
shaping and pulse forming circuits for the detec-
f. Balancing Motor B501. The balancing motor
tor. The servoarnplifier system contains the volt-
is a two-phase motor which is mechanically cou-
age amplifiers, power amplifiers, and pen-lifting
pled to the moving arm of the slide-wire poten-
and operating circuits, which are associated with
tiometer asd to the recording pen. One winding of
the balancing motor circuit in the frequency-time
the motor is connected to a 60-cycle excitation
recorder. The control panel supplies controls for
voltage, and the other (control ) winding is con-
the measuring circuits and the adjustments for
nected to the output of the servoamplifier circuit.
proper operation, and the power supply furnishes
When the balancing motor is actuated by the
the necessary operating potentials, The received
error voltage generated in the detector circuit, it
drives the slide-wire potentiometer contact arm.
radiosonde signals, regardless of their wave shape
The slide-wire contact arm voltage changes as the
and amplitude at the recorder input, are con-
balancing motor continues to revolve. When this
verted into a dc voltage which is proportional to
voltage becomes equal to the signal voltage ap-
the low recurrence frequency of the input signal
plied to the detector, the error voltage is canceled
at any instant, This dc voltage is then applied to
by the balanced-bridge condition, and the balanc-
an electromechanical recorder which translates it
ing motor stops. While the balancing motor ro-
tates the pen-lifter mechanism holds the pen
and marks off the frequency variations corre-
above the chart, the pen moves across the chart;
sponding to temperature and relative humidity
the pen makes no mark because it is in a lifted
readings as transmitted by the radiosonde. The
position. The sequence of operation is such that
chart can be read directly by a skilled operator or
the pen always marks the chart at a point that
used at a later date for further evaluation of each
corresponds to the meteorological information
radiosonde flight.
being received.

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