The 147.120 Tech Net Blog

KC4ZVW, Dave, commented on my last post and ask some basic questions that started me thinking. Does it work? It leads me to why I am building the BitX20. I have a strong desire to learn electronics. This project allows immediate feedback on each section that is completed.

When I completed the audio amp, I needed to find an input source to check it out. Travis, my son, and I built a crystal radio with an audio amplifier circuit. This Fox Delta design is made to learn with and has the ability to separate the audio amp from the crystal radio. I fed the signal into my BitX and it worked. I have already received the local AM station through my Bitx. DAVE, it works.

Then I built the Mic Amplifier. By jumping a signal and powering the audio amp section I was able to hear my own voice through my small amplifier setup. Yes it does squeal when you get the mic near the speaker just like the real audio setups, and yes I played with all the feedback noise I could create. That worked too.

I have completed all soldering on the radio. A radio is an oscillator that allows us to throw electromagnetic waves through the air and catch them at a different location. This radio has two oscillators. One is a carrier oscillator that is a 11.00001 Mhz, and the other is a variable oscillator, VFO, that is close to 3.0 Mhz. When combined, the frequency that adds up is near 14. Mhz, the 20m Band! Well , there’s a problem Dave. First, I have both signals oscillating and measurable although the VFO is only variable by 3.5 Khz. Not enough to qualify as a VFO. On this radio I will need a couple of hundred Khz to cover a portion of 20m phone band. I soldered in a different variable resistor and air variable capacitor and the oscillations stopped. I will go back on that change. Second, I am unable to find the 14. Mhz signal. I have unbalanced the modulator to let the carrier signal through to the mixer near the VFO and where I feel it should be, it ain’t.  There I is. Stuck again.

Dave, does it work? Wonderfully! I am learning radio theory, trouble shooting, soldersmoking, and burning my fingers. LIFE IS GOOD. Oh… the radio, well I’m sure it will work when I am done. 73

Robin

Bitx20A Alignment in Progess

Hello, I have been graciously allowed to post some thoughts about my ongoing relationship with a Bitx20A.

Where to begin… my name is Robin and I am a homebrewer. It all began when I found out you could build your own and learn about how a radio really works. No more black boxes with multiple-multifunction knobs and buttons for me. I was completely innocent, without a clue of the power this would have over me. Before I knew it I was a frequent-flyer at SkyCraft. Late night sessions at the dining room table with smoke wafting about as I ponder the perplexities of mixed oscillator signals filtered through polycrystalline mineral wafers. I still remember the joy of hearing the audible oscillations of my first Colpitts, but I digress. Consider the consequences, it is not for the faint of heart. If this is the path you choose, know what lies ahead. Capacitors that disintegrate before your eyes, signals that disappear after just a small tweak, and the frustration of “dang, I followed the directions and it don’t work”. I warned you!

That said, I will post a few photos and discuss my Bitx20 from time to time. I want to thank Tracy for his inspiration on the Tech Net and David for his Web expertise that allows me to be here. 73

Robin

Well, the BitX20 project is officially launching. Patrick KJ4JTK is keeping the list of participants so contact him to get involved. His email is pberry26 at yahoo dot com.

Here are the basics -

This is a course designed to teach the General Class Amateur Radio License theory by building a basic 20 meter SSB radio, illustrating the electronic theory required to pass the General Class License Exam. All sections of the General Class Exam will be covered in the course and the exam will be administered at the end of the course. The successful student will emerge from the course with a quality SSB radio and the license to operate it.

Registration must be in by October 31st
The course starts November 30th

Price for non-members is $200 which includes one year membership.
Price for existing members is $185 with lifetime members at $175. “Audit’ courses are available at $135 each for either the General Class License only or the BitX20 Radio only.

Meetings will be on Mondays and Thursdays from 7pm-9pm at KI4SDY Verns shop located basically at Ronald Regan Parkway and State Road 434. Holiday dates will be skipped.

There is a list of suggested tools to successfully build the radio. ‘Loaners’ will be available on a limited basis. There will be test equipment present at some of the building sessions.

This is sure to be a fun and productive project. Those participating on any level should grow in the knowledge of how SSB radio’s work, and a better understanding of basic electronic theory.

Q/A sessions will be handled on the Wednesday Night Tech Net as well as the Monday and Thursday sessions.

Contact Patrick to get on the list. Once registration is closed we will accept payment for the course and project.

Completion of the class / project will be just before the Orlando Hamcation and we will have a ‘Brag Booth’ there.

Feel free to ask any questions of myself or the appropriate parties listed here. The Wednesday Night Tech Net is always a good place to ask questions about this class and project.

Tracy N4LGH

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