So after coming home from the beach aka an activation, i put the uBitx on the bench and gave it a bit of a test out. Seems it needed some calibration work, the audio was way to tinny, so a bit of BFO fiddling was in order and a little LO calibration was needed also as it was way off frequency.
Well, I do want to say this about the uBitx calibration routines, they suck. There is no real way to get the radio any closer than 50hz off frequency. This is not good enough really and I know i can do better, but I am going to have to do a lot of code reworking so i can make the changes I require.
Anyway, thats not the point of this post, while i was sitting here trying to diagnose how I bricked the uBitx for the 4th time, i found out the lack of RF was a broken adaptor. Seems the arse fell out of it and there was no antenna thus no RF. Yeah Me 🙂
I guess it has happened to just about everyone. You drive for an hour, get to your destination and go to set-up the radio gear and notice you have left the antenna at home. LOL well it happened to me yesterday. Its the first time i have forgotten anything before.
So rather than waste all the effort, we popped over to Bribie Island and went to the beach. Its not radio, but have look at the weather. Nice huh.
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.