Yaesu FT DX 9000MP CONTEST - DATA MANAGEMENT OPERATION, Руководство по эксплуатации

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Page 167 FT
DX
9000MP O
PERATION
M
ANUAL
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The μ -Tune filters are the most advanced, selective RF preselector filters ever incorporated into an Amateur
Radio transceiver. The RF selectivity provided by μ -Tune can be of tremendous value in ensuring quiet, intermod-
free reception even in the most crowded bands on a contest weekend. The μ -Tune filters provide RF selectivity
on the order of a few dozen kHz at -6 dB, at the expense of a few dB of system gain on bands where noise figure
is seldom an issue. You will notice that the S-meter deflection, when
μ -Tune is engaged, is slightly less than
when it is out of the circuit; this is normal. If your antenna system gain is so low as to make it impossible to hear
band noise when
μ -Tune is engaged (highly unlikely), just switch it out or revert to the VRF system, which has
slightly less insertion loss.
P
As you tune around on an amateur band with μ -Tune engaged, the microprocessor automatically commands the
stepper motor driving the toroid core stack to center the filter on your current operating frequency (the tuning
resolution is 5 kHz). You may, however, use the [
VRF/ μ
] knob to skew the filter response to one side or the other
from your operating frequency, to deal with heavy interference on one side. To re-center the μ -Tune filter on
your operating frequency, and eliminate any offset, press and hold in the [ VRF/ μ
] switch for two seconds.
P
While μ -Tune is a superior RF preselection circuit, it may be disabled via the Menu; if this is done, the VRF
circuit will engage when the [ VRF/ μ
] switch is pressed. To disble
μ -Tune, go to Menu item “ GENERAL 043
μ TUNE DIAL STEP ” and set the selection to “OFF.”
Q Q
Q Q
Q
UICK UICK UICK UICK UICK
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O O O O OTE TE TE TE TE
The permeability-tuning concept utilized in the μ -Tune circuit dates back many decades, as it was incorporated in such
classic transceivers as the FT-101 and FT-901 series, in addition to the FT
DX
400 and similar models. The μ -Tune
circuit in the FT
DX
9000MP is the highest development of this circuit concept ever employed in an Amateur trans-
ceiver.
RF μ -T RF μ -T
RF μ -T RF μ -T
RF μ -T
UNING UNING
UNING UNING
UNING
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NITS NITS
NITS NITS
NITS
(((((MTU-160, MTU-80/40, MTU-30/20 MTU-160, MTU-80/40, MTU-30/20
MTU-160, MTU-80/40, MTU-30/20 MTU-160, MTU-80/40, MTU-30/20 MTU-160, MTU-80/40, MTU-30/20)))))