So i got the dipole up now in its final position. The coax is now clamped to the mast so there is no flapping about in the breeze. The ends are up at their finished height. All up we have 7.6m apex and about 3m at the ends. Seems to be working ok, rx is certainly up.
SWR is as good as it is going to get and much broader banded than the old shortened dipole.
Photo bombed by Buster the Boxer. This is some fancy engenerding going on here. There is a 6ft star dropper 2ft in the ground right up the masts clacker providing the main support, the 2nd star dropper is screwed to the retaining wall and some big automotive clamps tying the 2 together. No idea what the safe working limit on all these things are LOL, but it did not move much during the big storm we had go thought last night. So i think it should be ok.
Today i pulled down the old antenna and mast and put up a new and improved version of each. The old shortened 40m dipole was only ever meant to be a temporary solution that stayed in place for 3 years. So it was time to bring her down and put it to rest.
I bought a flag pole cause it seemed like a quick and simple way of putting up a new dipole and a balun because i want to be one of those balun guys who has to tell you what kind of balun he is using even though its kind of not important to the conversation but the word balun gives the air of technical know how and ability especially when you say its a 9 to 1 balun which is really an unun or as I call them 9:1 onions, because endfails will make you cry, but I digress. <– this is called sarcasm to anyone who is going to get hurt feelings over their antenna of choice, don’t email me call your local politician and complain to them.
Erected the flagpole and hoisted up the balun and new dipole cut for 40m on the flag raising rope, saluting while humming the national anthem and got the ends up in a temporary fashion to check the long or short of it with the analyzer, when the wife gets home from work. She comes out the back, looks at the new flag pole and remarks, Oh great, its storm season and you go and erect a dirty great big lightning attracter. Chuckles to herself and leaves me to antennaring like i know what i am doing. And if my Pythagoras is correct, when i put the ends up about 4m in the air, i should have 50mm to spare. The joy of living on a postage stamp block in the city.
I have been slowly clearing things off my bench either to the its complete pile or the it does not work look at it another day pile. And not that that is done, it is time to start on a major project that will take sometime to complete. I really wish I had the time to knock out rig a week like Pete Juliano, but alas I am neither that skilled or that time free LOL. Anyway, so what am i going to build, well a receiver to start with that might eventually morph into a transceiver.
Starting initially as a direct conversion and later becoming a single conversion superhet, It will loosely follow the simple-ceiver, simple-ceiver plus builds by Pete, which can be read about on his blog HERE: and a few bits off the bitx hacks page which can be found HERE:
Mixers will be Mini Circuits ADE-1, oscillators will be SI5351a with an Arduino powering it, audio will have AGC and some kind of audio filtering for both CW and SSB, I am currently not sure if i will go passive or use a Teensyduino and DSP audio filtering, I have the bits for both so either or can be done quite easily, but filtering will not be part of the initial audio amp build, all the rf amps will be Pete’s J310 as dual gate mosfet amps, bandpass filters will probably be my own 3 band switched module.
So that is the rough details of what I am planning to do, now its a matter of starting to build it. With that in mind, I will be starting tonight on the audio amp stage, using the AGC from bitx hacks for the bitx 40, a 2n3904 preamp by Pete Juliano and a TDA2822m in bridge mode. I will be building each stage on its own scrap of board for testing in isolation using manhattan construction and Me Squares.
So i got busy today and wired up the uBitx. Turned it on and tuned around a little to find some signals, well there was not much going on anywhere but I did manage to find this one ZL on an other wise dead band. Its good to know that the receiver works, now i just have to wire up a mic and check its working on transmit. But that is going to be another day.
So I recorded a little video from tonight’s 7.130 dx net. I have been giving the receiver a good workout to see how I like it. So far, to be honest, I think i prefer the Bitx40 over the uBitx. Though, it might be I just need to play with the IF and BFO settings to move the bandpass around a little to where I think it sounds better.
Started to put the uBitx into a case. I did the front panel up on a mini cnc and it certainly has turned out better than anything i have hand cut in the past. Used 1mm aluminium plate with is nice and easy to work with and the filing to clean it up at the end did not take long at all. Its not perfect, there are a few things that could have been aligned better, but it is what it is and that’s how its going to stay LOL.
Something i was not happy with was how the heatsinks were mounted flush to the board. If you use this radio portable eventually they will rub through the soldermask and short out on traces. So i grabbed a couple of other heatsinks i had laying about here, drilled and tapped for some isolation between heatsink and board. I also using insulating hardware as well because the fets tab is live and things go bad when you short things to ground that are not meant to be LOL.
Board is now mounted and just awaiting wiring up.
Front panel now with knobs on. Just have to wire it up and be done. Oh and yeah I use a speaker not headphones so I can use 1 less jack and I also use a 4 pin mic socket rather than jacks.
So, it been a rather big week at work and I did not want to start something that will take me weeks to build and I thought I would get this done today in an hour or so and be testing it. Well one thing lead to another and I still need to make the low pass filter for it. Well that looks like a job for tomorrow. Nothing extraordinary here, 100mhz oscillator and ADE-1 mixer and a 5v power rail for the oscillator.
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.
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.
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.