Advanced Interference; Suppression Features; Using The Vrf (Variable Rf Front-End Filter) - Yaesu FT DX 9000 CONTEST - MANUAL 2 Operation Manual

A I
DVANCED NTERFERENCE
U
SING THE
The VRF system is a high-performance RF front-end preselector that provides outstanding rejection of out-of-band signals.
1. Press the VRF/μ switch (#
LED inside the switch will become illuminated, and
the VRF system will be engaged, centered on your
current Amateur band.
2. You may rotate the VRF/μ knob (#
position of the VRF system relative to your operating
frequency. Because the VRF system is relatively broad,
although still much narrower than the fixed bandpass
filter), you may not hear much difference in the back-
ground noise or signal quality when you make minor
adjustments. However, if you have receiving problems
associated by a very strong signal, rotation of the
VRF/μ knob may help reduce the strength of the
interfering station, allowing improved reception of the
desired signal.
After moving the passband of the VRF system manually, you
may re-center it on the current Amateur band by pressing and
holding in the VRF/μ switch for two seconds.
To switch VRF off, press the VRF/μ switch momentarily
again. The LED imbedded in the switch will go out, and the
VRF circuit will be removed from the incoming received sig-
nal path.
Quick Point
The VRF filter, utilizing high-quality coils and capacitors
that provide high Q, yields a passband that is approximately
20% to 30% the width of a traditional, fixed bandpass fil-
ter. As a result, significantly more unwanted signal rejec-
tion is provided. Within each Amateur band, 64 adjust-
ment steps are provided (50 MHz: 8 steps), if you wish to
skew the response in a particular direction so as to en-
hance interference rejection even more.
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UPPRESSION
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VRF/μ knob
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PERATION ANUAL