howto:hambasics:b003
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howto:hambasics:b003 [2019/12/17 19:50] – [Transmitters] va7fi | howto:hambasics:b003 [2020/03/12 15:45] (current) – removed va7fi | ||
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- | ====== Station Assembly, Practice and Safety ====== | ||
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- | ===== Block Diagrams ===== | ||
- | The next few sections use block diagram to illustrate the construction of various pieces of equipment. | ||
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- | {{ youtube> | ||
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- | ===== HF Station ===== | ||
- | {{ : | ||
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- | Some of the components shown above may be integrated into one device, and others may be optional. | ||
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- | * The **transceiver** takes the audio from the microphone and creates a modulated radio signal. | ||
- | * 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. | ||
- | * A trick we use to protect the radio equipment is to add a **Tuner**. | ||
- | * 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. | ||
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- | 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. | ||
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- | ===== Transmitters ===== | ||
- | <WRAP round info box center 80%> | ||
- | **Review** the [[wavemodulation |Wave Modulation]] page. You should: | ||
- | * understand the difference between the // | ||
- | * understand the difference between //AM// and //FM//. | ||
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- | ==== FM Transmitter ==== | ||
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- | ==== CW Transmitter ==== | ||
- | {{ : | ||
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- | {{ : | ||
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- | * The **microphone** picks up the sound waves carried by the air and converts them into a weak electrical signal that becomes the // | ||
- | * The **speech amplifier** increases the strength of the baseband signal before it can modulate the carrier. | ||
- | * The **modulator** uses the baseband signal to change the carrier oscillator frequency in the next stage. | ||
- | * The **oscillator** generates a stable sine wave signal at the rest frequency when no modulation is applied. Its frequency changes linearly when fully modulated with no measurable change in amplitude. | ||
- | * The **frequency multiplier** increases the frequency of the modulated signal by a factor of 2, 3, or 4. This is so that the oscillator frequency can be lower than the frequency transmitted at the antenna. | ||
- | * The **amplifier** increases the power of the signal to be transmitted by the antenna. | ||
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- | ==== SSB Transmitter ==== | ||
- | {{ : | ||
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- | ===== Receivers ===== | ||
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- | ==== FM Receiver ==== | ||
- | Before we look at individual components, there' | ||
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- | {{ : | ||
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- | * The **RF amplifier** increases the strength of the weak radio signal received by the antenna. | ||
- | * The **local oscillator** creates pure sine wave that can be tuned by the listener. | ||
- | * The **mixer** takes in the RF signal and mixes it with the pure sine wave from the local oscillator. | ||
- | * The **filter** removes unwanted frequency created by the mixer and lets the IF pass through to the next stage. | ||
- | * The **IF amplifier** increases the strength of the IF signal. | ||
- | * At this point, the signal' | ||
- | * The **frequency discriminator** extracts the baseband signal. | ||
- | * The **audio amplifier** increases the strength of the baseband signal before passing it to the speaker. | ||
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- | ==== SSB/CW Receiver ==== | ||
- | {{ : | ||
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- | ===== Digital System ===== | ||
- | {{ : | ||
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- | ===== Regulated Power Supply ===== | ||
- | {{ : | ||
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- | ====== Questions ====== | ||
- | * B-003-001-001 -> B-003-003-010 | ||
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- | [[sections |{{/ | ||