DDS VFO

[Shadetree Mechanic]

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[claudineiw]

Alguém tem alguma informação nova ou experiência com a instalação de um desses?

E montei um desses em meu radio cobra 148 gtl. Funciona bem. Mas por questão do codigo fechado e limitado por conta do arduino. Estou desenvolvendo um software próprio. Que vou deixar aberto, depois de completo.

 

[DTB Radio]

Hasn't been an obvious problem in the ones we have installed so far. I was skeptical about the Si5351 chip, but so far so good.

What I really want to figure out how to do is use all three outputs from that chip to replace all 3 oscillators in the Tram D201A, not just the channel LO.

73

The general installation manual from the DDS-VFO website's help page covers how to set up CLK1 for a fixed frequency. CLK2 doesn't seem to be available in the DDS-VFO menu, but since the 5351 uses I2C for communication with the kit's Arduino Nano, you could probably install and connect a 2nd Arduino Nano controller and turn CLK2 on that way. Its easy to do with a very simple Arduino sketch. If you go that route, don't use the Adafruit 5351 library as its kind of klunky to work with. There are several other 5351 libraries available for Arduino that are simpler to use. My favorite is the Etherkit SI5351 library (NOT the JTEncode version). The basic example included when you install the library ("si5351_Example") already has everything you need to turn on any of the clocks with whatever frequency and power level you need. You don't even need the I2C address of the 5351 as the library finds it automatically.

Hope that helps!

 

[nomadradio]

Etherkit SI5351 library

has everything you need to turn on any of the clocks with whatever frequency and power level you need.

Way, way cool. What I want to do is generate the 5.8015 for the Tram D201's AM side, and be able to tweak it to match and compensate for whatever error the 455 filters introduce.

Then the 6.25x carrier, then the local oscillator for receive and transmit.

Had a disappointing experience plugging a Siltronix VFO in place of the D201's crystal syn board. The Siltronix' output impedance is just too high. The 6.25x MHz carrier signal pumps upstream into it. Gave it a headache. The D201 requires a really low output impedance from the local oscillator to the two mixers. Probably can't just couple the 5351 outputs directly, like in a solid-state PLL radio.

Would be cool to eliminate every crystal from a D201.

Just installed it. Looks like I can figure out how to use it.

73

 

[DTB Radio]

The output impedance of the 5351 is 50 ohms, with drive levels up to 8mA. Should be enough for any oscillator/crystal replacement needs you have.

For a more involved coding example than the samples provided with the Etherkit library, you can download the code I wrote for my key-pad-controlled raw signal generator from http://dtbradio.com/SI5351.html