TM 32-5835-005-14 & P
FUNCTIONING
OF
EQUIPMENT
Section
I.
INTRODUCTION
Reproducer Set. Information provided in
6-1. Scope of Section.
this section should be used as an aid in
This section provides a theory of oper-
performing the procedures detailed in
ation for use by maintenance personnel
other sections pertaining to isolation
at the direct support, general support
and repair of malfunctions in the equip-
ment.
and depot levels in understanding the
functions of the AN/UNH-17A, Recorder/
Section II. GENERAL
The head response curves show in each
6-2. Recorder/Reproducer (Transport).
case that overall response varies from
low frequencies to a mid-band peak by
a. Recording Technique. (See Figure
6 dB/octave. As this curve was made un-
6-1). Standard direct recording tech-
der constant current recording conditions,
niques are used in which a record am-
plifier and magnetic head transfer the
it is clear that this rise in response
occurs during playback. To equalize
time relationship of an input signal
directly to a magnetic tape. The signal
this curve, the playback amplifier must
provide a gain response complementing
amplifier conditions and amplifies the
the head response. From mid-band to
input signal and provides a current
high frequencies, a great degradation of
source for the record head proportional
head response is noted. This is due
to the applied input signal. This cre-
primarily to tape and head losses which
ates magnetic flux changes in the mag-
occur during the recording process. The
netic oxide coating of the tape which
playback amplifier is provided with ad-
correspond in intensity and timing to
the input signals. Since the flux den-
justable equalizers to introduce play-
back loss. In this way, frequency re-
sity in a magnetic medium does not vary
sponse with maximum overall flatness
linearly with the magnetizing force, the
is obtained.
data signal is superimposed on a high
frequency (50 KHz) bias signal to over-
c. Transport Functional Sections. The
come the hysterisis nonlinearity of the
magnetic tape. A symmetrical low dis-
Recorder/Reproducer is functionally div-
ided into the electro-mechanical tape
tortion bias signal is adjusted to op-
drive system, the control logic elec-
timize system parameters such as fre-
quency response, signal-to-noise ratio
tronics, the data signal electronics
and distortion. The data signal is ad-
and the power supply. The transport is
justed for recording at normal record
a casting that supports the mechanical
level (3% third harmonic distortion
subassemblies, and has no electronic
circuitry mounted on it. The data
upon reproduction of a 400 Hz signal at
signal amplifiers, logic control gating,
input record level of 0.77 VRMS.) The
bias and data signal record levels are
servo mechanism amplifiers and bias
both a function of the characteristics
oscillator are plug-in circuit boards.
Total access is obtained by removing
of the record head and magnetic tape
used and must be adjusted accordingly.
the top and bottom covers. The front
panel as well as the covers are provided
b. Equalization Technique. Figure
with a rubber gasket that is both a
moisture and RFI seal. All operator
6-2., a and b indicate typical response
controls and the tape cassette are front
curves for cassette recorders operating
panel accessible.
at 15/16 IPS and 1-7/8 IPS respectively.
6-1
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