Radio Books

I got to thinking the other day, as I was pondering placing an order for a couple more books from Pages of Cobram  that i have started to amass a bit of a library and I probably should write a bit of a review of them. Oh and if you are looking for a bookstore that is not going to mess you about and is competitively priced, give Peter as pages of Cobram a call and place your order there. Just about all my books have been purchased there and never had an issue, ever. I found a book that was not listed and they even ordered it in for me, a 1 off, cannot complain about that.

Anyway, on to the books:
Homebrew Cookbook and Building a Transceiver by Eamon Skelton: Skelton is a good writer and these books are and interesting read, however, cookbook contains a lot of the same material covered in transceiver. If i was buying all over again, i would pick one, either one and be done with it. I am not sure how useful transceiver is in actually being able to build a transceiver from whoa to go, but it is a good read that documents many of the decision making processes the home builder faces. A worthy read, with limited scope for developing the documented project. 6/10

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Experimental Methods in RF Design by Hayward et al: This is a book I love to hate, now dont get me wrong, this book is a tomb and a beast, jam packed with masses of information and probably the best text book we have on all things RF and Amateur Radio. Its just that it is hard to find the information you need, the flow is somewhat haphazard and illogical and it just tries to be all things to all men and does not really do any of them well. In some places its practical, in others massively theoretical. I think for me, I am always wanting the pertinent information and less of the fluff. Often times, bits of a schematic are just missing, like the number of turns on a bifilar winding, with a note to look in the transformer section, which is then masses of theory and I still do not understand why or how the turns ratio is calculated, other than most times in HF rigs, its 8T bifilar. Love it or hate it, or as i do, have a love hate relationship with it, its the best we have, but could be so much better and designed much more towards the practical person, rather than theory. 7.5/10

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Hands on Radio Experiments by Ward Silver: These books are copies of what was written in the Hands On column in the ARRL mag. The writing is great the projects great, its just its not a complete copy of the column and they are not in chronological order. Its a little frustrating when a project references a project not in the books, or if it is, you need to search all over to find it. I find myself reading bits and pieces of these books over and over, generally before bed. 7/10.

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Circuit Overload and RF Design Basics by John Fielding. Circuit overload is great lavatory reading, a useful schematic followed by an explanation of how and why it works. I have learned a fair bit from this book, all while sitting on the toilet. The sections on filters are almost identical in both books, and of all the books i have, these make the best explanation on how to design LC filters of anything i have read and for that info alone, make these books useful. 6.5/10

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Radio Projects for the Amateur 1,2,3,4 by Drew Diamond: I find these books to be inspirational, while i am not all that interested in anyone project to build in its own right, when i am stuck for an idea, or a solution, these books seems to have it. The books themselves are copies of articles Drew has written for other publications, the explanations and descriptions are good, and generally give you all the information you really need to know without too much fluff. I will often pick one of these books at random and read an article or 2 before i go to sleep. 8/10

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I have a couple more books i will add to this list later, and I have some new ones coming soon that I will also add to this list. Happy home brewing.

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Arduino Logger

Sometime ago after a long discussion with a fellow ham, we has concocted this idea to create a logging application using an arduino. The whole thing has sat stagnate for so long, with the parts to make it sitting in the box for many many months, that I decided it was time to pull them out and start to put some work into the ideas.

Basically you have an Arduino Uno, PS2 Keyboard, SD Card Reader, and 20×4 LCD with I2C to form up the basics of the unit. At a latter stage i may also include a RTC clock so that you do not have to manually enter date and time, but for now, i am not sure how will both the LCD and RTC would work together on the I2C port together and if one or the other is going to hog to much time slice.

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The basic idea can be seen in the image above. Feature wise, it will be able to take your call, todays date and mode, their call, time, rpt rx, rpt tx, and some short notes like the name and location as well as being able to change mode on the fly and also being able to create a new log file as needed. This is something i wish to use myself while out portable, so i can leave my expensive laptops and their battery hunter or expensive tablet at home. Yeah i have had a tablet die on my portable and lost over 150 log entries from 3 WWFF parks. The way the data will be saved in my arduino logger will be every new entry a backup will be made and the new entry will be written to file, worst case scenario you lose 1 entry, not 100’s. Unless the card explodes and well then you are totally buggered anyway. Here is a small video of where we are at with the project and in a few days i should have something very usable happening.

UPDATE:

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Added in a real time clock so that there is no date and time entries, we can just poll the clock and get the data we need.

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Finished off the basic setup, of Your Call, Band and Mode.

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Direct Conversion Receiver with DDS VFO

So not to be outdone with just one project on the go, I also get it in my head to rebuild the 2-IC DC Receiver from page 1.8 of EMRFD. I have built this simple receiver before, it was one of my first projects ever and it worked first time out of the box, well kind of.

My original was built Manhattan style, but at the time, being rather newbie, i was not able to make the LC oscillator circuit with sufficient Q to make the thing work. It was yanked out and initially replaced with an xtal, making it rock bound and of limited use, then the xtal was removed and replaced with an Arduino DDS VFO and my love of DDS was born LOL.

My first project that gave excellent results, I was receiving stations from all across Australia, New Zealand, Japan and the USA. It was thrilling. I was now hooked on homebrew.

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Above is the schematic of the circuit, i have changed out the local oscillator for a DDS VFO, and i have made a couple of minor changed to the audio amp, mainly double the gain it will now put out maximum gain, the only issue no gain control on the audio amp.

 

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Board was laid out in Sprint Layout, with extra holes drilled for mounting the DDS board onto it.

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Its a nice simple project, wont take long to solder it up and get it on the air and tuning the 40m band.

UPDATE:

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So it is all together and it works ok. I did have to change a few things, mainly making the audio single ended rather than differential, this gave much more audio at the speaker. Also the tank, while it functions, does not seem to do all that much, tuning it by the trimmer, yields no change what so ever. Its something i will need to look at.

While its working, it could do with some improvements, especially to the front end. Here is a video showing it working.

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Super VXO

Ok, so mostly I am a DDS and Arduino kind of guy, they just work, they don’t drift and they are super simple. But sometimes, you get that “Retro” kind of nostalgia happening and a desire to build something rock bound. I have a ton of crystals in matched pairs for 7mhz, enough to cover the whole CW portion to 7.050. So i thought, what the hell, I will make a Super VXO, and incorporate it into a transceiver if it proves to be stable enough.

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So i went looking for a suitable circuit to modify to suit my parts bin and needs. And i came across this one above. Varactor tuning is nice, as getting quality air variable caps and reduction drives is impossible, so varactors are must. The only thing i changed is the inductor as I do not have any Toko IF coils, and the only other thing i changed was to add an unbalanced to balanced transformer to split the signal in to, one for the receiver and the other for the transmitter. The original article and associated info for this Super VXO can be foundĀ HERE!!

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Laid the board out in Sprint Layout, and after ironing out the bugs with the help of Ben VK6FBLJ who put his eyes over the layout and noticed all the errors, the gerbers were then converted to gcode for routing.

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Could fit 2 boards on the one sheet of FR4 the above picture is the boards on the mill deck still after routing and v-cutting in two.

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And this is the finished board after being cleaned with steel wool and a coat of PCB lacquer being applied. They have come up rather nice looking. More to come on this, after they have been built and tested to see how stable they are.

UPDATE 1:
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Most of the parts are installed, I threw in a pair of 10mhz xtals for testing with, they will not be the what is used in the final board, but are good enough for testing purposes. Just have the inductors to wind, 10 turn pot to wire up and the 8v regulator to install and it is ready for smoke test. Oh and i was able to find a MV2109 varactor in my semi conductor box, so, no cheeping out and using a silicon rectifier.

UPDATE 2:

Well i cannot get this thing to start oscillating. Have tried just about everything i can think of, will post back when i work out what the case is.

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