For active antenna use, do not connect an antenna to the MAIN ANTENNA
connector.
Use
a wire antenna can be connected to the rear panel NOISE
ANTENNA connector, J1. Best results will be obtained by using the longest practical
length of wire for this antenna.
When used as an active antenna, set the NOISE PHASE control fully clockwise for
best results. Set the FREQ RANGE pushbutton to agree with the frequency band in
which you are operating. The position of the PHASE RANGE pushbutton is not
important.
Following are some helpful hints for operating with the ANC-4:
To prevent damage to the ANC-4 when an antenna tuner is used,
simply turn off the power on the ANC-4 until the tuning process
is complete.
If the PHASE GAIN control is too close to either the CCW or CW
end,merely adjust the noise antenna length to center the control. In
other words, keep the noise antenna length to the minimum required
to get a good null while keeping the NOISE GAIN control in its mid
range.
If you use an antenna tuner, wait until the antenna has been properly matched
before adjusting the ANC-4 for local noise null.
If the local noise is not stronger in the noise antenna than it is in the main antenna,
adjusting for a null will likely reduce the desired signal as well. It is desirable
to have the noise antenna as close to the noise source as possible for best
performance, so an external noise antenna may be required.
DO NOT connect the noise antenna to a high gain outside antenna unless a series
attenuator is used. Unless the signal is attenuated, the received signals will
overload the internal amplifier and will cause intermodulation distortion. The
loss in signal strength through the attenuator can be made up by adjusting the
NOISE GAIN control.
You will likely find that the ANC-4 will make operation of a DSP noise reducer,
such as the Timewave DSP-599zx., much more effective because the ANC-4
will eliminate noise before it gets into the receiver and affects the receiver AGC
circuits.
If you are situated close to an AM broadcast station, you may need to trap the BC
signal to prevent overload of the noise amplifier in the ANC-4. A tunable trap
is included on the pc board to eliminate BC station interference. See Section 2,
BROADCAST BAND NOTCH for further information. If more than one station
is involved, merely place jumper JP3 in position 1-2. This engages a highpass
filter which attenuates the broadcast band by at least 50 dB.
NOTE: If the NOISE GAIN is set too high, the ANC-4 will introduce noise
instead of removing it. Noise cancellation is dependent upon a good balance
between the NOISE PHASE and NOISE GAIN controls.
If two antennas are available and located with space diversity, you can use the
ANC-4 to null interfering stations as shown in figure below.
In order to obtain the best noise null, it may be necessary to change the noise
antenna polarization (horizontal or vertical) to be the same as that of the main
station antenna.
11
GENERAL
OPERATING HINTS
