Vertex Standard FT-2000 ユーザーズマニュアル
Page 51
FT-2000 O
PERATING
M
ANUAL
IPO (I
NTERCEPT
P
OINT
O
PTIMIZATION
)
The IPO feature allows the operator to optimize the characteristics of the receiver front end, depending on the current noise
level and the strength of incoming signals.
level and the strength of incoming signals.
Press the [IPO] button several times to set the
desired characteristic of the receiver front end,
per the chart below.
desired characteristic of the receiver front end,
per the chart below.
AMP1
:
Amplifies the incoming signal path using a
low distortion RF preamplifier (gain: approx.
10 dB).
low distortion RF preamplifier (gain: approx.
10 dB).
AMP2
:
Amplifies incoming signal path using a 2-
stage low-distortion RF preamplifier (total
gain: approx. 17 dB).
stage low-distortion RF preamplifier (total
gain: approx. 17 dB).
ON
:
Bypasses the RF preamplifier, yielding di-
rect feed to the first mixer.
rect feed to the first mixer.
The selected receiver RF preamplifier will be indicated in
the IPO column
of the Receiver
Configuration
Indicator on the display.
the IPO column
of the Receiver
Configuration
Indicator on the display.
A
DVICE
:
On the 10 MHz and lower bands, it generally is not necessary to use any preamplifier at all; selecting the “ON” position
described above will increase the strong-signal-handling capability of the receiver, and generally will result in more pleas-
ant reception due to reduced noise. If you can hear band noise with the preamplifiers disengaged, then a preamplifier is
generally not needed.
described above will increase the strong-signal-handling capability of the receiver, and generally will result in more pleas-
ant reception due to reduced noise. If you can hear band noise with the preamplifiers disengaged, then a preamplifier is
generally not needed.
ATT
Even with the IPO function on, extremely strong local signals or high noise can still degrade reception. In such situations,
you can use the [ATT] button to insert 6, 12, or 18-dB of RF attenuation in front of the RF amplifier.
you can use the [ATT] button to insert 6, 12, or 18-dB of RF attenuation in front of the RF amplifier.
Receiver Configuration Indicator
[IPO] Button
1. Press the [ATT] button several times to set
the desired attenuation level, per the chart
below.
OFF
below.
OFF
:
Attenuator is Off
–6 dB
:
The incoming signal power is reduced by 6
dB (Signal voltage reduced by 1/2)
dB (Signal voltage reduced by 1/2)
–12 dB
: The incoming signal power is reduced by 12
dB (Signal voltage reduced by 1/4)
–18 dB
: The incoming signal power is reduced by 18
dB (Signal voltage reduced by 1/8)
The selected
attenuation
level will be
indicated in the ATT column of the Receiver Configu-
ration Indicator on the display.
attenuation
level will be
indicated in the ATT column of the Receiver Configu-
ration Indicator on the display.
Receiver Configuration Indicator
[ATT] Button
C
ONVENIENCE
F
EATURES
A
DVICE
:
The Attenuator affects both the Main (VFO-A) and Sub (VFO-B) bands.
If background noise causes the S-meter to deflect on clear frequencies, press the [ATT] button until the S-meter drops to
about “S-1.” This setting optimizes the trade-offs between sensitivity, noise, and interference immunity. Also, once you have
tuned in a station you want to work, you may want to reduce sensitivity further (or add more attenuation) by pressing the
[ATT] button to a more setting. This reduces the strength of all signals (and noise) and can make reception more comfort-
able, important especially during long QSOs. When looking for weak signals on a quiet band, you will want maximum
sensitivity, so the IPO should be disabled and the [ATT] button should be set to “OFF.” This situation is typical during quiet
times on frequencies above 21 MHz, and when using a small or negative-gain receiving antenna on other bands.
tuned in a station you want to work, you may want to reduce sensitivity further (or add more attenuation) by pressing the
[ATT] button to a more setting. This reduces the strength of all signals (and noise) and can make reception more comfort-
able, important especially during long QSOs. When looking for weak signals on a quiet band, you will want maximum
sensitivity, so the IPO should be disabled and the [ATT] button should be set to “OFF.” This situation is typical during quiet
times on frequencies above 21 MHz, and when using a small or negative-gain receiving antenna on other bands.
2. To restore full signal strength through the Attenuator
circuit area, press the [ATT] button to restore the ATT
display to the “OFF” position.
display to the “OFF” position.
AMP1
AMP
AMP
AMP2
ON