Μ-Tune Filter - Yaesu FT DX 3000 Operating Manual

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The RF µTuning Kit provides ultra-sharp RF selectivity for the front end of the transceiver. Very high Q is made pos-
sible by the narrow-band design. Three RF µTuning Kits are available. The MTU-160 covers the 1.8 MHz band. The
MTU-80/40 covers the 3.5 and 7 MHz bands. The MTU-30/20 covers 10.1 and 14 MHz bands.
When any (or all) of the three optional units are connected, they will be automatically adjusted to center on your operat-
ing frequency.
The narrow bandwidth is especially useful on the low bands, when many strong signals are being received via NVIS
propagation (Near Vertical-Incidence Signals) within a narrow bandwidth. The added protection for the RF stage is es-
pecially helpful in preventing IMD and blocking.
µ-Tune Operation
1. Press and hold in the [ MHz/µT ] button for one sec-
ond to activate the µ-Tune filter. The LED inside the
[ MHz/µT ] button will glow red. The [ CLAR/VFO-
B ] knob works as the µ-TUNING knob.
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 The µ-Tune circuit will automatically align itself
to the operating frequency.
 Remember that µ-Tune only operates on the 14
MHz and lower bands.
2. Rotate the [ CLAR/VFO-B ] knob to peak the re-
sponse (background noise) or reduce interference.
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 You may observe the relative peak point of the
µ-Tune filter in the Tuning Offset Indicator on
the VFO-B frequency display, while tuning the
[ CLAR/VFO-B ] knob.
 The amount of change in the center frequency
of the µ-Tune filter, when rotating the [ CLAR/
VFO-B ] knob, can be configured using Menu
item "044 µTUNE DIAL STEP".
 If the μ-Tune filter has been manually adjusted
away from the center frequency, you may press
the [ CLEAR ] button to re-center the filter re-
sponse on the current operating frequency.
3. Press and hold in the [ MHz/µT ] button for one sec-
ond to disengage the µ-Tune filter
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Alternate presses of the [ MHz/µT ] button will switch
the µ-Tune filter between on or off.
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 The µ-Tune Filter selection will be memorized in-
dependently on each VFO stack of the VFO-A and
VFO-B.
 You may change the indication of the Tuning Offset
Indicator to display the µ-Tune filter continuously
while the µ-Tune filter is activated. This is Menu
item "010 BAR DISPLAY SELECT". See the Box on
the next page for details of the setting.
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 The µ-Tune filters are the most advanced, selective
RF preselector filters ever incorporated into an Ama-
teur Radio transceiver. The RF selectivity provided
by µ-Tune can be of tremendous value in ensur-
ing 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 that you cannot hear the band
noise when µ-Tune is engaged (highly unlikely), just
switch it out, to eliminate the slight insertion loss.
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K
it
[ MHz/µT ] Button
[ CLAR/VFO-B ] Button
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