Superheterodyne Receiver Book

Discussion in 'General Electronics Chat' started by KCHARROIS, Oct 7, 2012.

  1. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    Hello,

    I am in the need of a book that could teach me how to design a superheterodyne receiver or at least something that could show me how to designs pieces of the superheterodyne receiver. Any books you guys have in mind?

    Thanks
     
  2. cork_ie

    Member

    Oct 8, 2011
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    There are lots and lots of Superhet circuits available online. I doubt you will need to buy a book.

    I would start by looking at some of the older Valve (Tube) radio designs as they are generally simpler and easier to understand.
     
  3. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    Yes but I need a book to help me design one or how to design the parts of a superheterodyne receiver such as mixer, local oscillatr, rf amp, demodulator, etc.
     
  4. bertus

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    JohnInTX, PackratKing and KCHARROIS like this.
  5. Wendy

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    Mar 24, 2008
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    The basics all exist pretty much individually, and can be looked up on the internet with great ease.

    However, if you need a paper book, think amateur radio. HAMs do this stuff routinely.
     
  6. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    Great find Bertus this should be great thanks, I'll definitely look through HAM as well.
     
  7. bertus

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  8. KCHARROIS

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    Jun 29, 2012
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    Hello again,

    Ok so I've looked at few links and have to decided I'd like to build a superheterodyne AM receiver. Most circuit I see seem to use IC's, but usualy before I use IC's i build something with discrete components to prove to myself I learned something. I do understand the topology behind superheterodyne receivers but I dont know how to design them. Is it worth trying to build something with discrete components or should I stick using IC's with some discrete components?

    Thanks
     
  9. vk6zgo

    Active Member

    Jul 21, 2012
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    The ARRL Handbook,or RSGB Manual,especially older ones,have quite a lot on Superheterodynes.

    The Superheterodyne principle is the single most important circuit design concept utilised in RF Communications Electronics.
    It is used in almost all aspects of that industry.

    Although other methods are being used,they are still in the minority,compared to the equipment using the Superheterodyne principle.

    After all,a Direct Conversion (D.C.) Receiver is just like a Superhet,except that it has a zero frequency IF.

    A Digital direct sampling receiver also uses many of the same concepts.
    Sampling?,mixing?--very much the same thing,looked at from a different perspective.

    If you have a signal generator,& can make up,or obtain a mixer,you can begin to get hands on experience with the building blocks of Superhets.

    A good start is to make a HF converter to use with a MW AM radio,using the above bits.---it will be "as rough as guts",& won't work at all well,but you'll be learning.
     
  10. vk6zgo

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    Jul 21, 2012
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  11. Dodgydave

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    Jun 22, 2012
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  12. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    Ok so I look at these links and I cant tell you how confusing everything looks. I'm currently going to niagara college and the only thing I've learned in RF is the topology of most transmitters and receivers. I understand there building blocks on what each part does but nothing on designing them and putting it all together to make a receiver or transmitter. I feel like rf is out of my league how long did it take for you guys to design one? What kind of education did u get to design one? Are there online courses i could take?
     
  13. bertus

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  14. Wendy

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    The trick with any design is to break it down. The hetrodyne circuit is the only really odd part with this radio.

    Have you seen a block diagram of a superhetrodyne radio?

    Have you ever built a crystal radio? This applies, because (believe it or not) this section is in almost every AM radio built.
     
  15. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    I do understand the building blocks of a superheterodyne receiver, I just dont know how to design each section and then adding it all together. And no I have never built a crystal radio.

    http://www.mikroe.com/old/books/rrbook/rrbook.htm

    This link is great for me because it identifies every piece. For the simples AM superheterodyne receiver section I understand that the incoming signal is mixed with the oscillator to produce an IF of 455 KHz whihc is a standard and then it goes throu a filter designed for a certain bandwidth suppressing all other incoming signals. And then it goes through the demodulator and then amp and then speakers. The part that confuses me the most is the Local oscillator piece and the MFT filter section. If I could understand what component he used and how they work, I believe this you'd give me a good reference point to move on.
     
  16. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    So I started looken at VCO's typically using the colpits fprmat with the use of a varactor to control the frequency. I've attached the picture of the circuit im analyzing.

    What I understand is the Varactor and Inductor determine frequency, C1 blocks DC but what I dont seem to get are the other 2 capacitors from the base to emitter, I know they give the circuit feedback that keeps the oscillator going but what values do you choose for them?

    Thanks in advance
     
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  17. panic mode

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    Oct 10, 2011
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  18. KCHARROIS

    Thread Starter Member

    Jun 29, 2012
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    Forgot to add circuit its updated from last post.
     
  19. vk6zgo

    Active Member

    Jul 21, 2012
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    Many of us know a lot about Receivers & Transmitters.

    We have built them from other people's designs,fixed commercially made ones when they have failed,& indeed,immersed ourselves,at one time or another,in the circuitry involved,but probably only a few of us have designed either from scratch.

    Don't get too bogged down on the "building blocks" approach.
    Although it is a quite useful idea,remember that the Radio is one device,so you should keep in mind how each "block" works with the other ones.

    The Blocks in "Block Diagrams" may not correspond to how you would separate the bits into "blocks",prior to putting them together.

    I think you are over-analysing things.
    Just for now,assume an "oscillator is an oscillator",& the niceties of the oscillator circuit don't really matter in your understanding of a Superheterodyne circuit.
    This is why I suggested you use a Signal Generator as your Local Oscillator for your first few forays into this kind of Receiver.

    OK,if you particularly want to study oscillators as a separate thing,get into the "nitty-gritty" of them then.
     
  20. vk6zgo

    Active Member

    Jul 21, 2012
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    Wait! There's more!!:D
    The "other 2 capacitors" are in fact the capacitive part of the LC circuit.
    The varactor just "trims" the frequency.
    The formula which you can use to determine their value appears here:-

    http://en.wikipedia.org/wiki/Colpitts_oscillator#Oscillation_frequency

    Note:- Just about every website has an infatuation with Common Base Colpitts circuits,but the Maths are the same for your circuit.
     
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