4562Re: [ScoutRadio] Blinker Morse App
- Aug 8, 2014
Are you asking how many code practice or side tone oscillators are in a typical transceiver ( which would be one in my opinion ) or how many AF and RF oscillators in a transceiver?
The latter can vary depending on how many levels of conversion and if the system used dedicated oscillators in the transmit and receive sections, and for each band in the band switching circuits. There are QRP rigs that use one in an oscillator - amplifier transmit with direct conversion receive configuration.
A classic super heterodyne receiver would have a band select oscillator that feeds the first mixer, classically it was LC tuned with switched coils for band change, but some used crystals at the first stage and variable oscillators for tuning at the second stage. Some designs used separate oscillators for each band rather than switch tuning elements to one active device. In the classic design there would be a BFO (Beat Frequency Oscillator ) that injected a signal into the detector stage. Functionally that would change the AM detector into a second mixer so that you could hear CW as a tone, and of course after SSB became popular the function became standard instead of a separate control.
Transmitters started as simple oscillator - amplifier devices. From there came oscillator - modulator - amplifier, and into the more complex one and two mixer configurations.
Transceivers began in the earlier days as a way to use common components sections in both the transmit and receive functions. I think the most common configuration is for the first and second mixers, as well as the IF strip to be used jointly, with the HF local oscillator to used to set the frequency.
And then phased locked loops got into the equipment and microprocessor controllers so you might have to add clock oscillators as well.
Modern transceivers that use direct digital synthesis and the push for software defined radio have shifted the design issues like oscillator stability so the common configurations may have changed that I am not familiar with.
That is a lot of related information, but I don't think there is a simple answer to your question. I am somewhat concerned that the issue of how many oscillators are in a typical transceiver may make it difficult to have relevance to introducing Scouts to electronics and radio by building a code practice oscillator or demonstrations of Morse code with blinking lights.
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