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.
Today I got a mic connected to the uBitx and a key and was able to test that its making RF and doing its thing. My home antenna is resonant on 40m, so i do not need to check the swr or anything, but i thought i would use the power meter in the swr meter to check what the power output of the uBitx is. Trouble was, it was making about 5w cw and 3w ssb.
So i got to scratching my head and wondering about the radio itself. I was about to put it in the cannot be bothered for today pile when i grabbed down the scope probe, put it across the antenna port and keyed up cw, 22v rms or 10 watts out, so i grabbed the mic and spoke in my normal voice, 21v rms or about 10w out.
Obviously the power side of this swr meter is kind of crap and not giving an accurate measure of power out. Anyway, i know the uBitx is working now and making enough power to be useful, now all i gotta do is get out portable and use it.
A friend of mine, Simon, VK6MSC has set up a Kiwi SDR radio that is running 24/7. Apart from his qth having a very high noise floor, the radio itself seems to work quite well and is a good tool if you want to check propagation to VK6, which is a land far far away.
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.
I got rather excited this arvo and setup the mini cnc mill and went and bought some 1mm aluminium sheet with the grand idea to cnc out a front panel for the uBitx, because lets face it when it comes to cutting a straight line I suck big time. So i got on the computer and fired up Aspire Vectric and laid out a front panel with all the mounting holes etc being peck drilled for me to drill out to the right size later on the drill press. Things were going quite well until i realised i made it 100mm too short. Oh well, its now a tomorrow job.
Most things are having a hard time with the summer heat, but the corn is going great guns. I spaced the plants a little farther apart this time and offset them. Next time I am thinking of running a single row along the back of each bed as some of the ones at the back have not gown as fully as others, I am thinking its because they are being shaded slightly. We’ll see, its a work in progress.