Technical talks for 2008. The design of HF Transmitters, Receivers, and Antennas.
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Transcript of Technical talks for 2008. The design of HF Transmitters, Receivers, and Antennas.
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Technical talks for 2008
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The design of HF
Transmitters,
Receivers,
and Antennas.
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The format of the talks
The talks will be semi theoretical
Speakers should be available for discussions afterwards or on other weeks
Some will want a deeper understanding
Others just want to use technology confidently
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Practical examples will be used where possible
Suitable group projects will be identified
Anonymous feedback forms will be used
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Reference designs
In order to retain our focus we will regularly refer to the circuit diagrams
of two kits.
The BITX20 and the SoftRock 40/80m.
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BITX20
Picture from Hendricks QRP Kits
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It’s a fairly simple transceiver
It uses few circuit variations
It does not use software
Why the BITX20?
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We will learn to break down “big” circuit diagrams (next)
Don’t Panic!
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BITX20 bidirectional SSB transceiver
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A BITX20 single stage
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We will learn to break down small circuit diagrams even
smaller.
(Another day)
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SoftRock RxTx 40/80m
Picture from Nicolas M1HOG.com
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It uses a range of circuit variations
It is a more modern design
It introduces digital techniques
Why the SoftRock RxTx?
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SoftRock Receiver
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Many of the same principles are used in the:
The SDR Transmitter
(avert your eyes for now if you like)
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SoftRock Transmitter
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These circuits were just to set the scene.
We will come back to them during the following talks:-
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Fundamentals
Current, voltage
Conductors, resistors
Potential dividers
Kirchoff's laws
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Signals & test equipment
DC / AC
Signal Generators
Graphs, Time, Amplitude, Frequency, Phase(using visualisation tools)
Oscilloscopes (practical to follow)
RC Bridges & Grid Dip Oscillators
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Electric and Magnetic Fields
Electric fields, capacitors
Magnetic Fields (Using visualisation tools)
Magnetic Materials, Inductors and Transformers (Bifilar winding, Baluns)
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Analogue circuit design
Diodes, Transistors (Bipolar, FET), Valves
Transistor circuits: Common emitter, emitter follower, common base, biasing, feedback.
Transistor pairs: Cascode, long tailed, mirror.
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Introduction to integrated circuits
ICs are not scary: lets look inside
Operational amplifiers & their internal design
Gates, flip-flops, transmission gates
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The first commercial op-amp, the K2-W 1952
http://www.ieee.org/portal/site/sscs/menuitem.f07ee9e3b2a01d06bb9305765bac26c8/index.jsp?&pName=sscs_level1_article&TheCat=2171&path=sscs/07Fall&file=Lee.xml
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Analogue signal processing
Superhet (supersonic heterodyne) receivers
Mixers (multipliers). Single / double balanced
Filters (RC, RC active, LCR passive)
Filter design with passives or op-amps
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Electro Magnetic Fields (e.g. radio waves)
Transmission lines / coax cables
Propagating EM Fields
Fundamental Antenna theory (dipoles)
Antenna matching / tuning
Phased arrays / Yagis
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Digital signal processing
Digital Communications e.g. PSK31
A/D & D/A, Shannon’s law, sampling theory
Some more logic circuits
Direct Digital Synthesis (DDS)
Digital filters and their design
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Demonstrations of digital signal processing
These will be non-theoretical demonstrations of signal processing using a Field Programmable Gate Array (FPGA) demo system.
If interested this can be followed up with more detail and a live demonstration of programming