Independent Power Supply
For Local Oscillator
One consequence of the relatively high impedance of
power supplies is that leakage from the +B line of the
power supply unit can feed back to the local oscillator to
modulate the local oscillator frequency. This causes tuning
problem by eliminating the source itself
— the + B line to
the oscillator, giving the local oscillator its own independent
power supply. With two power supplies, noise due to leak•
age is virtually non-existent, even at 100% modulation. In
inaccuracies by deflecting the tuned frequency above and the KT-1000, this is perfectly utilized.
below its optimum level. Kenwood engineers solved this
High QualityAM Section
AM sections that are as carefully designed as FM sections.
In the past, AM sections of FM/AM stereo tuners have
tended to be neglected because of the generally inferior
quality of AM broadcasts. Now, Kenwood tuners are fully
able to reproduce the upgraded AM broadcast quality, with
In the KT-1000 an IF band selector is provided for the AM
section.
Sample-And-Hold
MPXCircuit
As with the Pulse Count Detector, Kenwood engineers have
taken advantage of the exceptional accuracy of digital pro•
cessing with the introduction of the Sample-and-Hold multi•
plex decoder. This circuit cleanly extracts the left and right
channel signals from the composite FM signal carried by
the 38 kHz subcarrier frequency. The wave peaks are con•
verted into digital equivalents in the form of pulses. Since
only the basic shape of the waves are converted into digital
equivalents, transient deflections in the shape of waves
caused by noise or distortion are ignored. This greatly
reduces the need for filtering, which vastly improves chan•
nel separation, because filtering can obscure important
information in the composite signal, interfering with the abili•
ty to isolate left and right channel signals. The peak pulses
are sampled then held in a capacitor until the next peak ar•
rives; thus, the average peak value can be instantly adjusted
for precise representation of the original 38 kHz subcarrier.
The KT-1000 employs this superior type of MPX decoder.
Quartz Synthesizer
Preset Tuning
Kenwood's quartz-PLL tuning circuit uses the ultra-stable
oscillating frequency of a quartz crystal to keep the fre•
quency generated by the local oscillator locked to the exact
tuning frequency. The quartz-PLL circuit can be preset to
automatically tune to any one of any combination of as
many as eight different FM or AM stations. To preset, the
desired station is manually tuned in, and then the preset
button is pressed, after which any one of eight station
buttons may be pressed. Whenever that station is desired,
pressing the station button previously selected will
automatically tune the station. This system is fully utilized in
the KT-800.
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