Ham Radio General Class Practice Test

Which of the following most limits the effectiveness of an HF mobile transceiver operating in the 75 meter band?

1. "Picket Fencing" signal variation

2. The wire gauge of the DC power line to the transceiver

3. The antenna system

4. FCC rules limiting mobile output power on the 75 meter band

The correct answer is: The antenna system

The effectiveness of an HF mobile transceiver operating in the 75 meter band is most limited by the antenna system. In HF communication, effective radiation of the radio frequency signal is crucial, and the antenna plays a significant role in determining how well the transceiver can transmit and receive signals. An inefficient or poorly resonated antenna can lead to loss of signal strength, decreased range, and reduced overall performance in communication. Factors such as antenna height, design, length, and tuning directly influence an antenna's ability to resonate at the desired frequency. In mobile applications, space constraints often limit antenna size, which can further compromise performance. Moreover, mobile antennas can be affected by the vehicle's body, which may detune the antenna or create interference patterns that can impede effective communication. The other choices have their own impacts but to a lesser extent compared to the antenna system itself. "Picket Fencing" describes signal variations experienced due to multipath propagation but is more related to the reception quality than a fundamental limit on capability. The wire gauge of the DC power line can affect the efficiency of power supplied to the transceiver, but it would not be the primary limiting factor compared to antenna performance. Lastly, while FCC rules are important for compliance with legal power limits,