L Match With SWR Bridge Cont:

Putting the finishing touches to the antenna tuner project, I just need to cut the shafts down a little and put the knobs on. I have given it a test into 2 dummy loads, a dummy load and my 40m antenna LOL, and the led comes on super bright with 5w going in. All in all I am pleased with the outcome, though i would have preferred it in a smaller case, but the inductors use kind of determined the case it when in.



QRP L Match With SWR Bridge

So with the new year comes new projects, I am not going to set out what my overall plans and goals are as I have started way to many things and never bothered to see them through or to complete them. So with that in mind, I am building a L match

Its hard to make out, but you can just see the LED glowing, the signal is 10v p-p from the signal generator, the load is a decade resistance box. At infinite swr there is 1/2 the p-p voltage at the junction of the rectifier and capacitor. As swr approaches 1:1 the voltage drops to a point where the LED turns off. Its simple and its a winner.

It will get paired up with the sotabeams switched inductor and a 8-370pf air capacitor. as an L match. Should be good enough for the kinds of girls i go out with. Below is the schematic I am following for this project and a link to the authors site is at the bottom of the page. In the final build I will use 3w 50ohm resistors and the diode i used was a Schottky, i don’t recall the numbers it was just something i had in the parts box, I used the Schottky for its lower voltage drop, though that is probably not all that critical seeing that LED’s are current limited, not voltage.

Link to authors blog post: HERE



VK4FFAB Portable Station

So i finally got around to sticking the arduino logger into a box, and other than the fact that I cannot cut a straight line to save myself, it does not look all that bad and it will be somewhat protected now. I also spent some time aligning the IF on the Bitx 40. The software on the arduino vfo is code that I wrote and the display was always off by 1270hz. So i played with the IF frequency in the code and got it to be pretty close to being spot on. Its just about perfect on receive and so far no one has commented on the audio so I will take that as it sounds good enough that no one is going to get upset. Going to try and get out this weekend and activate a park or 2 for wwff.


LED Bezels

So months ago i bought 100 LED Bezels, it seemed like a good idea at the time and something i would later find use for. So today when i actually need one for a project, i go looking for them and cannot find them. It is not like my shit is a mess, its rather neat and tidy and somewhat organised with like things with like things. But can i find the LED Bezels, nope. No fucking idea at all and I have been through each and every tray looking for them.


Sotabeams Switched Inductor

This is an interesting little kit and not much information on the net about its use so I thought that I would add a quick blog entry about what I discovered about it. I am building an L match and started with the inductor. I really had no idea on windings, so i started with 6 turns and added 2 turns per inductor, with the 7th inductor having 18 turns on it. I spent about 20mins working out the switch, it is meant to be a 6 position switch, which in reality is a 10 position switch with a limiter. However in my case, it looks like i was given a 5 position 2 pole switch. While mildly annoying, with 5 positions I get 270nH -> 3.7uH inductance, and if i switch from the low side input to the high side input gives 1.7 -> 5.5uH, while adding switching is a pain in the arse, it is not the end of the world to have one inductor not in the loop. If i had realised before soldering in the switch i would have used a 10 position switch i have here and made it work right from the beginning. It is what it is, no use worrying about it now. 3.7uh is more than enough inductance for any antenna i build.