Thursday, December 4, 2014

Hand Full of Parts...

One of the ideas I'd been toying with doing for the "Great American Teach In" involved breadboard building a regen live. I found a circuit in W1FB's design notebook, and began assembling the parts for it. I asked my daughter's teacher when the teach-in would be held, and she indicated that the new principal rescheduled it in the spring. I shelved the parts, thinking I would wait until winter to test the circuit out, I didn't want to rush.

The parts sat on my workbench tucked into a corner, out of the way, but not completely out of sight or out of mind.  I prewound the tank circuit on a pillbottle, and put the handfull of parts the radio needs inside it. All except a pot, and a couple of caps. I'm still debating what to do about the tuning cap. The circuit calls for a 100pf variable cap, and I have some orange trimmers that would work (max 70pf), if I left it on a quasi-fixed frequency, perhaps in the neighborhood of 3579 KHZ (wink wink). On Sunday, my five year old (call her G.) needed to play outside, and I decided to go out, and monitor her from my shack, perhaps snagging a QSO or two on one of the high bands. Here's what I saw when I walked into the shack:

had to take this in sideways

 I needed to tidy up a bit.
I did some tidying up and now my shack looks a lot better. Still needs work, but progress is progress. One of the things that popped up front was the little regen kit...

My big girls have shown some interest in what their Dad does in the weird looking, funny smelling shed in the back yard, and they frequently ask me for a "radio project". Usually, what that means is taking one of my old junker radios, and tapping various parts with screwdrivers. I'm cool with that most of the time, keeps them busy, and maybe one day this seed will grow into a desire to learn radio. The five year old has been showing interest too, and she popped in the shack while I was cleaning up.
"Can I have a radio?" she asks, normally, she gets the little Vectronics 80m Direct Conversion radio kit I got when I was single, lived in Atlanta, and wanted something to accompany my NoGANaut. The last time she "Fixed" it, she destroyed several components on the board that I would have liked to junk off of it.
"Baby girl, last time, you broke parts I can't fix."
"But I'm five now, and I'm not a baby, I want to build my own!"
I can argue with cute, and I can argue with logic, but when you combine cute and logic, what can I really do?
"Ok, come check this out,"
I took out the kit, showed her the parts, and we looked at the schematic:

 We began looking around for any of the parts that were missing in the kit. I'm still looking for a 1k pot, we found a 500 ohm pot, and I might try that, and if it doesn't work, we'll make something up as we go along.
Soon we had to get back inside and get our supper. Every day since then she's asked about "putting together her radio". Yesterday we started populating a board with some of the parts. We haven't 100% settled on a final box for this, probably do an altoids tin, because I've got about a million of them. 

We had to find some caps:

Searching for Unobtanium

 An ever elusive component, the 100pf NP0 capacitor foils every effort I make at homebrewing. I set G to searching them out from a jumble of leads and discs that comprised a baggie of "assorted capacitors" from RadioShack. There were NO 100pf caps in the whole thing. Fortunately, my SK Elmer, W3IRZ taught me that 3 33pf caps in parallel work very well for a 100pf cap.

learning by doing
When the task of sorting the caps got to a stopping point, G wanted to play with the DVM, she learned that a cap is "good" if the 1 shows up on the ohmmeter. She also learned about potentiometers, and how turning the knob makes them change value. After stuffing the board with a few resistors, the 2N4416, and the LM386, we called it a day.

She's already asked me about her radio once this morning, maybe we'll make time to learn about soldering!


Dan KC7VDA said...

My Daughters went thru the same process, all are now very self sufficient ( and Happily Married)
See Ham radio is good for something!

Gary Auchard said...

Looks like an interesting project. I don't have this book in my library. What is the winding info on the coil? I'd like to make one of these as I've lately been building various regen receivers.

Gary A. - W0MNA

GB Hoyt said...

Hi Gary,
from the Notebook:
"L2 has 22uH of inductance to cover 3.4-8.5MHz with C1, Use 46 turns of no. 26 enam. wire, close wound, on a 1-inch dia x 2-inch coil form. Place tap at 11 turns above the grounded end of the coil. L1 has 5 turns of no. 26 enam. wire, close wound, over the grounded end of L2"