FCC E4B - 业余电台实践与测试

#E4B01🔗

Which of the following factors most affects the accuracy of a frequency counter?

以下哪个因素对频率计数器的精度影响最大？

Input attenuator accuracy

输入衰减器精度

Time base accuracy

时基精度

✓ 正确答案

Decade divider accuracy

十年分频器精度

Temperature coefficient of the logic

逻辑温度系数

#E4B02🔗

What is the significance of voltmeter sensitivity expressed in ohms per volt?

以欧姆每伏表示的电压表灵敏度有何意义？

The full scale reading of the voltmeter multiplied by its ohms per volt rating is the input impedance of the voltmeter

电压表的满量程读数乘以每伏额定值的欧姆数就是电压表的输入阻抗

✓ 正确答案

The reading in volts multiplied by the ohms per volt rating will determine the power drawn by the device under test

伏特读数乘以每伏特额定值的欧姆数将确定被测设备消耗的功率

The reading in ohms divided by the ohms per volt rating will determine the voltage applied to the circuit

欧姆读数除以欧姆每伏额定值将确定施加到电路的电压

The full scale reading in amps divided by ohms per volt rating will determine the size of shunt needed

以安培为单位的满量程读数除以每伏特额定值的欧姆数将确定所需分流器的大小

#E4B03🔗

Which S parameter is equivalent to forward gain?

哪个 S 参数相当于前向增益？

S11

S12

S21

✓ 正确答案

S22

#E4B04🔗

Which S parameter represents input port return loss or reflection coefficient (equivalent to VSWR)?

哪个S参数代表输入端口回波损耗或反射系数（相当于VSWR）？

S11

✓ 正确答案

S12

S21

S22

#E4B05🔗

What three test loads are used to calibrate an RF vector network analyzer?

使用哪三种测试负载来校准射频矢量网络分析仪？

50 ohms, 75 ohms, and 90 ohms

50 欧姆、75 欧姆和 90 欧姆

Short circuit, open circuit, and 50 ohms

短路、开路、50欧姆

✓ 正确答案

Short circuit, open circuit, and resonant circuit

短路、开路、谐振电路

50 ohms through 1/8 wavelength, 1/4 wavelength, and 1/2 wavelength of coaxial cable

50欧姆通过同轴电缆的1/8波长、1/4波长和1/2波长

#E4B06🔗

How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?

当连接在发射机和终端负载之间的定向功率计读取 100 瓦正向功率和 25 瓦反射功率时，负载吸收了多少功率？

100 watts

100瓦

125 watts

125瓦

112.5 watts

112.5瓦

75 watts

75瓦

✓ 正确答案

#E4B07🔗

What do the subscripts of S parameters represent?

S参数的下标代表什么？

The port or ports at which measurements are made

进行测量的一个或多个端口

✓ 正确答案

The relative time between measurements

测量之间的相对时间

Relative quality of the data

数据的相对质量

Frequency order of the measurements

测量的频率顺序

#E4B08🔗

Which of the following can be used to determine the Q of a series-tuned circuit?

以下哪一项可用于确定串联调谐电路的 Q 值？

The ratio of inductive reactance to capacitive reactance

感抗与容抗之比

The frequency shift

频移

The bandwidth of the circuit's frequency response

电路频率响应的带宽

✓ 正确答案

The resonant frequency of the circuit

电路的谐振频率

#E4B09🔗

Which of the following can be measured by a two-port vector network analyzer?

二端口矢量网络分析仪可以测量以下哪些内容？

Phase noise

相位噪声

Filter frequency response

滤波器频率响应

✓ 正确答案

Pulse rise time

脉冲上升时间

Forward power

正向功率

#E4B10🔗

Which of the following methods measures intermodulation distortion in an SSB transmitter?

以下哪种方法可测量 SSB 发射机中的互调失真？

Modulate the transmitter using two RF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer

使用具有非谐波相关频率的两个 RF 信号调制发射机，并使用频谱分析仪观察 RF 输出

Modulate the transmitter using two AF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer

使用具有非谐波相关频率的两个 AF 信号调制发射机，并使用频谱分析仪观察 RF 输出

✓ 正确答案

Modulate the transmitter using two AF signals having harmonically related frequencies and observe the RF output with a peak reading wattmeter

使用具有谐波相关频率的两个 AF 信号调制发射机，并使用峰值读数瓦特计观察 RF 输出

Modulate the transmitter using two RF signals having harmonically related frequencies and observe the RF output with a logic analyzer

使用具有谐波相关频率的两个 RF 信号调制发射机，并使用逻辑分析仪观察 RF 输出

#E4B11🔗

Which of the following can be measured with a vector network analyzer?

使用矢量网络分析仪可以测量以下哪些内容？

Input impedance

输入阻抗

Output impedance

输出阻抗

Reflection coefficient

反射系数

All these choices are correct

所有这些选项都是正确的

✓ 正确答案

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FCC E4B - 业余电台实践与测试

小节 E4B：业余电台实践与测试