Author: Rob Powell

The Tribander, A Redux

I got excited today and moved the tribander, improved its radial situation, made it work so much better and found out why it became a dummy load. The 1:1 balun I had on it to stop rf in the shack on 10m was full of water.

It went from having 1 wire radial each for 20, 15 and 10m, to having 4 horizontal aluminium radials 2.5m long each and 4 wire radials 5m long each.

I am not so worried about 15m, the 40m quarter wave does a great job there, but getting 10 and 20 working better is the aim here. Under 2:1 swr would be fine enough. The 20m radials are not optimized yet, so the plot will change somewhat mostly i am trying to improve the 20m situation.

And here is the final business. Its not super high in the air, about 5m to the base of the antenna, but its good enough until I can build a tower that will support and rotate a yagi, The vertical will end up becoming a 2 element yagi, I have the traps already thanks to a mate.

And just to prove its working, the RBN plot.

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Fake It, Till You Make It

Making antennas is a shit business LOL. I have never found it to be a fun aspect of the hobby. But as the focus of my dxcc chasing is moving to 10m and the fact that I have completed 20 and 15m using the same antenna I have been using for donkeys nuts, I figured it is time up upgrade to a Yagi. 3 elephants on 10m is a reasonable antenna and as you can see in the image below, I have all the tube sitting there as left overs.

After looking at the various design options, what crap I have on hand and the like, the easiest yagi for me to build is a through the boom design with a gamma match. So then, if i cannot build a gamma matched dipole for 2m on the bench, there is no way in hell that I could build a yagi for 10m.

I know this looks dodgy as, and that is because it is. Crap is held together with duct tape, love and a hope and a prayer. This is the 3rd edition of dicking about here. The gamma match calculators were, well to say the least, kind of fucking useless. So I isolated the variables and just went at it one variable at a time to see the effect they have. Added capacitance first, moved the tap point second and finally changed the distance between radiator and match and in the end, I think i got a bit of an understanding of what does what.

A few hours later and I have this plot, not bad all things considered, like is connected to a bit of wood in a vice, its got alloy tube really close to it, its right next to the work bench and its stapled together with duct tape. But, I think I am now able to take this knowledge and turn it into a 10m yagi. For shits and giggles I might take what I have here and turn out 4 elephants for 2m and point it at the local repeater for full quieting HAHAHA.

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DXCC on 2 Bands

Kind of cool that I have 20 and 15m done now for DXCC, the next big focus will be on building a yagi for 10m and getting it in the air and trying to smash out 10m dxcc on the up of the cycle and during winter here, trying to add to 40m as well.

 

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Coding Like A Champ

So yesterday I got back into programming the control software for my home brew rig. One thing that I needed to tackle, among all the other things I got done, was to display and format the VFO frequency. Now anyone who has used some of the original authors code and or a derivative of the various Arduino VFO’s you can find on the web, will know that how they format and display the frequency as say 7.000.230 is not very readable. In fact, it requires a lot of mental gymnastics to work out which digit is being divided down for and what the remainder is to be displayed. So I set about to doing this my way so that my display code is much more readable and that it was obvious which digit was being calculated and displayed.

So, I created a function that takes two parameters and returns the remainder. N is the digit to be split off the number and int_ToSplit is the actual displayed VFO frequency. So if the VFO was 7,125.000 and you wanted to know the digit in the thousands column, all you have to do is Do_SplitInt(3, 7125000), where 3 is the 4th column from the right, C being every count starts at 0 and all.

From here its just a matter of wrapping it up in a sprintf call and using some variables and the actual formatting when using a TFT display where you have to give X and Y coordinates to position each number becomes rather trivial.

Cant say I am a design genius, but at least its all my own work, thought and design.
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