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how can i design ham radio transmitter?what do i require for ssb modulation instead simple am modulation? Answered



Are you a qualified HAM operator ?


Yes. Just to add to Slowpoke's answer I think you should also look at QRP magazines and articles, as these have theory and practical circuit examples.

1st: Are you a licensed amateur radio operator? If not, get licensed. There are significant penalties involved for operating transmission equipment if you are not licensed. Studying to get the license involves gaining some of the knowledge that you are inquiring about.

2nd: I recommend the ARRL or the RSGB Amateur Radio Handbooks. These books are full of relevant information. However if you want to see what is involved with SSB devices, get hold of the circuit & block diagrams for something similar to a COBRA 142GTL-A AM/SSB 27MHz radio and study them (try SAMS Fotofacts, if they are still around or just check out the Cobra site). I recommend another book called Understanding & Repairing CB Radios by Lou Franklin of CB City International (www.cbcintl.com). This book goes into some detail regarding the operation of SSB circuits and explains it very simply (the mathematics are presented in a very easy to understand manner).

3rd: The basic heart of an SSB generator is a device known as a Ring Modulator followed by a Crystal Filter. The ring modulator generates a Double Sideband output (DSB) and the filter knocks off one of the sidebands that isn't wanted. There are several ways of generating SSB but these units are these easiest to set up & get going. A very good ring modulator IC is the AN612. Crystal filters can be very expensive, so using CB parts is an economical alternative.

4th: If you are or become a licensed amateur operator and your budget is very low, obtain an old 27MHz AM/SSB radio and feed it into a down-converter. This device is simple to build and has the advantage of also allowing you to receive on the frequency that you were transmitting on. Also the old 27MHz radio could be modified to operate on the frequency that you want. I have an old Cybernet radio (PLL02A Chassis) that works on 50-52MHz, this was a major rework of the radio, but it works very well.

So, you may have the impression that I am saying that what you want to do is very difficult. It is, but there is no reason that you shouldn't try. The spirit of Amateur Radio is experimentation and support from other Amateurs that can help with your projects.

Check out eHam, ARRL and any amateur site that refers to Homebrewing (non-alcoholic). Also Ten-Tec offer full blown amateur radio kits that allow you to build your own radio. Several other places do as well. Me, I just buy faulty radios and bring them back to life.


Now THAT is what I call a complete answer. Brilliant piece.

Just clarify one point: The ring modulator in an SSB generator circuit is commonly known as a Balanced Modulator. There is a difference between a standard ring modulator and a balanced modulator. The balanced modulator produces a DSB output with both sidebands being equal in amplitude and the carrier frequency suppressed. A ring modulator doesn't fully suppress the carrier frequency.