McIntosh MAC 4100, Руководство пользователя, Страница: 18 / 27

IMAGE REJECTION
80 dB IHF minimum
STEREO SEPARATION
45 dB minimum at 1 kHz
SCA REJECTION
60 dB minimum
GENERAL
SEMICONDUCTOR COMPLEMENT
45 Transistors
31 Integrated Circuits
62 Diodes
1 Silicon Controlled Rectifier
MECHANICAL INFORMATION
SIZE:
In cabinet: 18-5/8 inches (473.1mm) wide, 6-1/2 in-
ches (165.1mm) high, 15-1/2 inches (393.7mm) deep.
Without cabinet: Front panel measures 17-9/16 in-
ches (446.1mm) wide by 5-1/4 inches (133.4mm} high.
Chassis measures 17-1/8 inches (435mm) wide by
4-15/16 inches (125.4mm) high by 13-1/2 inches
(342.9mm) deep. Knob and handle clearance re-
quired is 1-1/16 inches (27mm) in front of the moun-
ting surface.
FINISH:
Front panel is clear anodized to produce a brushed
satin - silver finish with black anodized trim. Cabinet
is walnut grained vinyl
WEIGHT:
42 pounds (19 kg) net
56 pounds (25.4 kg) in shipping carton
Technical Description
Engineering direction dictated a receiver design
governed by insistence on a preamplifier with ex-
cellent flexibility, a FM section with great sensitivity
and high selectivity, an AM section whose perfor-
mance maximizes reception capabilities and a high
performance, high power stereo power amplifier.
These values were achieved and they retain the
Mclntosh reputation of long life and reliability.
FM SECTION
The radio frequency [RF section] houses the com-
plete FM-RF front end and part of the AM-RF cir-
cuitry. A seven section variable capacitor is the
heart of the RF section. Four sections of the variable
capacitor are used for FM. The remaining three are
used in the AM section. By interleaving the sections:
AM/FM/AM/FM etc., spurious responses have been
significantly reduced. The use of the latest state of
the art MOS field effect transistors as well as a
carefully designed variable tuning capacitor has pro-
vided a high degree of RF selectivity and excellent
spurious response rejection. Image rejection and
spurious responses have been brought to a
minimum in the RF section. A dual insulated gate
metal oxide silicon field effect transistor [MOS-FET]
is used as the first RF amplifier. Each gate of the
transistor is internally protected by zener diodes
against incoming externally generated transients.
Use of the MOS-FET greatly reduces cross modula-
tion over a wider dynamic range. This dynamic range
permits the input circuit to accept extremely strong
signals without overload. The mixer has been
designed to use another MOS-FET for high sensitivi-
ty, low cross modulation, and freedom from
overload. Low temperature co-efficient components
are used in the FM local oscillator to prevent fre-
quency drift. This assures that you are properly tun-
ed to the station. For optimum signal transfer and
lower distortion, a special matching transformer has
been designed to interface the FM-RF to the FM-IF
amplifier. This matching transformer improves
phase linearity of the IF amplifier.
All of the RF circuits to the FM sections of the
variable capacitor are encased in a metal module.
Within the metal module each FM-RF section is
separately shielded by metal partitions. This ex-
treme shielding gives protection against radiation or
interference.
Antenna connections for either 300 ohm twin lead
transmission line or 75 ohm coaxial cable are provid-
ed on the rear panel. The normal input impedance of
the RF amplifier is 75 ohms. Impedance match to
300 ohms is provided by a Mclntosh designed balun
transformer. Connections for a 300 ohm line are
made with push type terminals that do not require
the use of tools. For the 75 ohm input, a type F con-
nector is provided.
The FM-IF section consists of five integrated cir-
cuits and four piezo-electric filters. They combine to
give a total gain of over 140 dB. The signal is
amplified ten million times. The response curve has
nearly linear phase characteristics. The skirts of the
response curve are very steep. The maximum width
is 170 kHz at 3 dB and 500 kHz at 60 dB. The
response is symmetrical each side of the center fre-
quency. The filters are permanently sealed and
never require adjustment and cannot drift nor vibrate
out of adjustment. The exceptionally high gain of
the five integrated circuits assures hard limiting at
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