Yaesu FTDX9000MP Operation Manual page 169

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.
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.
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 042
μTUNE DIAL STEP" and set the selection to "OFF."
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
circuit in the FT 9000MP is the highest development of this circuit concept ever employed in an Amateur trans-
DX
ceiver.
FT 9000MP O
DX PERATION
RF μ-T RF μ-T U U U U U
RF μ-T RF μ-T RF μ-T
UNING UNING UNING
UNING UNING
A A A A A
D D D D D VICE VICE VICE VICE VICE
Q Q Q Q Q N N N N N
UICK UICK UICK UICK UICK
M
ANUAL
NITS NITS ( ( ( ( ( MTU-160, MTU-80/40, MTU-30/20 NITS MTU-160, MTU-80/40, MTU-30/20 ) ) ) ) )
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
O O O O O TE TE TE TE TE
400 and similar models. The μ-Tune
DX
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