Transceiver Control Board

Control board PCB design files

It seems like now days every man and his dog has a DDS/Digital Synth VFO project happening. I have had a couple and I am pretty sure that there are even Gerbers floating about on my blog for that very thing and was one of the very first boards I ever designed and laid out.

Well, times are a changing and rather than just a simple VFO, I have designed a board to control all aspects of radio control. To fit all the functions into one microcontroller required a bit of a step up and the use of an ATMega because I needed that many digital pins.

So what does it do? Well:
1. Real time clock and keyboard for logging contacts, digital modes like RTTY and keyboard CW.

2. Rotary encoder for the SI5351a VFO obviously.

3. 8 push buttons for various functions like band changing, mode changing and setting the attenuation level. On my front end board i have a 32 step rf attenuator in 0.5db steps, and for selecting 1 of 2 audio filters, but this might change yet and become DSP audio filtering with a lot more options at a latter stage.

4. Setting relays both bandpass and lowpass filters for 4 bands and selecting one of 2 IF Filters.

Now i am only releasing the board files, the software is something you are going to have to write yourself, because my code is not complete and probably wont be complete for sometime. I have most of the basic functionality written, but it all needs fleshing out and cleaning up. Now its nice when someone does it all for you, but, this will be pretty slick when complete and well, i dont want anyone making a commercial product out of my work and so the code will probably never be released. But these board files will save you hours of work, even if you have to code it all yourself.

The latest iteration of the control board


Early prototype board working and functioning. 

Gerber files for this board can be downloaded from here: http://vk4ffab.info/Files/ControlBoard.zip

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Steamed Snapper, Asian Style

This is no Pasta Pete recipe and I am not as famous as the man himself, but, I do cook, can cook and now and again knock one out of the park.

Tonight’s dinner steamed whole snapper with stir fried vege and noodles. The fish is stuffed with chili, ginger, garlic and spring onion, and topped with the same and a good splash of soy sauce and sesame oil. Steam in a bamboo basket until cooked.

The vege is just anything you like, I did red capsicum, zucchini, beans, snow peas, carrot and mushrooms, in a little Yaki Udon sauce and some slurpy Korean noodles.

If the proof is in the eating, all said and done, there was nothing left on the plate.


Fish all prepped and ready for steaming.

The final dish as served to the table. 
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4 Band Bandpass Filter Board

The relays are double pole double throw in a standard 18x9mm package size. The transistors are anything you have in CBE footprint, I used 2n3904 and the resistor is there for current limiting, just pick a typical value, i think i used 4.8K. The trimmer caps I use are 3 leg 100pf max value to tune and align each filter.

SMA edge connectors bring RF in on the left side of the board. By default all relays are in the OFF position and no RF can pass through. The 6 pin header brings control signals and power to the board. To turn a relay on, a 5v control control signal is placed on one of the first 4 pins to turn 1 pair of relays on. The last 2 pins are ground and VCC of the relays you used.

Aligning each filter can be a bit tricky, it is best to use a spectrum analyzer and tracking generator if you have one, or a noise source and spectrum analyzer or even in a pinch if you slow down the seconds/division on the oscilloscope so you can see the filter shape. The reason being, if your filters are not quite tuned right, you will end up with 2 peaks and some attenuation in the bandpass you just do not want.

The filters themselves are Double Tuned circuits. To design the values needed for each band I used some software called DTC.exe which can be found on a CD in the book Experimental Methods In RF Design. I have linked it here for download, but I am not sure if I am allowed to and i will pull it down if asked by the authors: DTC DOWNLOAD

The gerber files for the board can be downloaded from here: Bandpass Filters

Here is a schematic of the filters with values for 80, 40, 20 and 15m.


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4 Band Lowpass Filter Board

Board Design 

Ok, in the spirit of sharing and making things easy for people, I am going to start releasing some gerbers for the various boards I have designed for my various projects, that work HAHAHA, because, yes, not everything i do works.

I am not into this for making money, I do everything that i do simply for the love of it and for the learning experience. So selling boards and things is not high on my agenda. And besides, you can get 10 boards made and send to you from JLCpcb in China for not much more than it would cost me to send you one from Australia.


First cab off the ranks 7th order low pass filter boards. So you will notice there are no part values on the boards. Why? Well because i do not know what bands you might like to build for. The relays are double pole double throw in a standard 18x9mm package size. The transistors are anything you have in CBE footprint, I used 2n3904 and the resistor is there for current limiting, just pick a typical value, i think i used 4.8K.

SMA edge connectors bring RF in on the left side of the board. By default all relays are in the OFF position and no RF can pass through. The 6 pin header brings control signals and power to the board. To turn a relay on, a 5v control control signal is placed on one of the first 4 pins to turn 1 pair of relays on. The last 2 pins are ground and VCC of the relays you used.

For designing the filters I use an online calculator like this one at Calculators Edge: http://www.calculatoredge.com/electronics/bw%20pi%20low%20pass.htm Or a software tool like Elsie.

Lowpass Filter Board

Gerber Files can be downloaded from HERE:  http://vk4ffab.info/Files/LowPass_Filter.zip


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24 Hours of 20m WSPR

It really makes you wonder doesn’t it, when you look at this map of WSPR spots for a 24 hour period whether the developing world lacks the means to be able to setup WSPR beacons and ham stations in general or if they just lack propagation. The former obviously for many reasons.

I have been thinking for sometime that it would be nice to develop a WSPR transmitter that is that cheap that we in the west could make 100’s and ship them off to schools across the middle east, Africa and south America along with STEM tools for teachers to use radio in their science classes. Something in the $20 to $30 region, easy to assemble and not worth stealing because no one would really want it.

The benefits would be great for students as far as stem education goes and for us in the developed world, with lots of free time and disposable income to put into hobbies we would have a ready made beacon network to all corners of the world.

Ashar Farhan has done great work in philanthropic radio using the Bitx to support a collective of women in work. Perhaps this same approach could be put to use to bring the wonders of amateur radio to schools in the developed world.

24 hour wspr map from VK4HAT station.

Some food for thought.

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Radio Bebek 40m QRP Transceiver

Radio Bebek by the Bogor Homebrew Radio Community in Indonesia. Its an interesting little qrp radio that uses very common off the shell parts, mostly. There are a couple of oddities and absolutely no build instructions at all. So its not a build for the faint of heart, its a lot of reading the schematic and buzzing out the board to know what goes where because there are NO Part Designations on the board, only values and in some cases those values are wrong. But, i am having a go at building it and seeing how i get on with no instructions and only a schematic. Wish me luck. I do not think i will make this a transceiver, but will build it as a receiver only as i want to match this up to a 10w CW transmitter i have built.

The project can be found here on the authors website. http://blekokqrp.blogspot.com/2018/08/radio-bebek-40m-lsbusbdigital-qrp.html

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