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howto:hambasics:b003

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Station Assembly, Practice and Safety

HF Station

Some of the components shown above may be integrated into one device, and others may be optional. But if all are included, this is how they should be connected.

  • The transceiver takes the audio from the microphone and creates a modulated radio signal. Typical HF radios can output about 100W of power. Hams with their advanced ticket can feed that into...
  • The amplifier takes the radio signal from the transceiver and amplifies its power to 1 kW or even 1.5 kW.
  • From there, the signal may contain higher frequencies (called harmonics) that are not desirable, so it goes through a Low Pass Filter, which passes low frequencies and filters out high ones.
  • After that, the SWR Bridge measures how much of the signal is reflected back toward the radio from the antenna system. We saw earlier that the length of the antenna needs to match the frequency we use. When the match isn't perfect, some of the radio signal “bounces” at the antenna back to the radio, which isn't good for the equipment. The SWR Bridge measures this.
  • A trick we use to protect the radio equipment is to add a Tuner. This device uses varying combinations of capacitors and inductors (more on this later) to match the impedance of the antenna system to the radio (more on that later). Although there is still reflection at the antenna back toward the radio system, the tuner will “protect” the radio from it.
  • An Antenna Switch is a handy piece of equipment to quickly switch between antennas without having to disconnect and connect coax connectors.
  • Because of their size difference, it's usual to have a multiband antenna that will work on 20m, 17m, 15m, 12m, and 10m (and maybe even 6m), and a second antenna for 40m, 80m (and maybe even 160m).
  • Where as a tuner for the upper band is optional if the antenna is well designed, the lower bands (specially 80m and 160m) are very wide compared to their frequencies so it's practically impossible to have an antenna that will work over the entire band. For that reason, a tuner for these bands is pretty much mandatory.
  • The Dummy Load is a 50Ω resistor that can dissipate all the power from the radio without converting any of it into a radio waves. It's useful for test purposes or to tune an amplifier.

All that being said, it's possible to go on HF with a transceiver that has an small integrated tuner in it, and a single antenna. It'll just be a matter of knowing which frequencies your system can transmit on, and stay within them.

FM Transmitter

FM Receiver

Questions

howto/hambasics/b003.1574829589.txt.gz · Last modified: 2019/11/26 20:39 by ve7hzf