Engineer from Télécom Paris
Ph.D Thesis from UPMC

Network & Security IT - MI
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Very low cost function generator for ham radio

I had no money to buy this state-of-the-art DDS function generator that goes up to 20 MHz, to test my HF amplifier. So, I bought a low cost medium frequency DDS function generator (Centrad GF265, up to 5 MHz) for low and medium frequencies experiments, and used a few simple discrete analog components to get a signal at 20 MHz. The board is made of two parts: a Colpitts oscillator followed by a power amplifier. Each part needs a RF transistor, so I used two BFR96TS NPN RF transistors. As you can see on the following schematics, to get a signal at 20 MHz, I only needed 2 transitors, 7 capacitors, 3 coils and a few resistors.

Now, let's use this 20MHz signal generator to compare my 21th century 2x25MHz PCS500 numeric oscilloscope and my new (but very old) Tektronix 465 2x100MHz analog one, that came out of the factory in 1975. As you can see on the following picture, the 33 years old oscilloscope is very good, compared to the new one. More over, the trigger of the Tektro was difficult to fine tune but it finally gave a very stable signal display. The trigger of the Velleman never gave a stable signal display.

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Learn how to make a 20MHz HF signal generator using a few simple discrete analog components. Moreover, see how a 33 years old Tektronix oscilloscope gives better results than a numeric one bought recently. The whole story is here.

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External Links:

ImageMy Former Web Site
Since 04/26/01, I maintain a web site named Since I made many updates recently, click here to access the original content, where old informations are kept. The photo is also from 2001 :-)

ImageAgnes' Web Site
Agnes, my wife, used to maintain a web server but she doesn't anymore. Thus, this pointer is disabled. However, you may contact her on LinkedIn.

ImageCanardou's Web Site
Canardou has always been for me a friend that really matters, helping me in every situation. According to informations currently available, Canardou could be affected by the H5N1 virus. So, for a few weeks, Public Health Bird Regulations have made me forbid Canardou to walk away from our appartement. Feel free to take news about him from his personal home page.

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Authorized users at domain can read/send mails by means of this cute Squirrel (a friend of Canardou ?).