Saturday, December 13, 2014

The Lightbulb Came On When the Lightbulb Came On

Sitting on the floor with a battery, jumper wires with alligator clips, a small light bulb, she traces the circuit in the picture on the book. She'd seen me put the circuit together and now she wanted to do it herself.

It all started with a well intentioned mistake. She cares about making sure her mom and I understand when she's cleaning something up. Getting cooperation in picking up her room, or putting away toys is as big a challenge as it can be for any five year old, but sooner or later things start to click, and it begins to come automatically. In this case, she was very proud of the fact that she was taking the batteries out of their packaging and putting them in a smaller box.

Because I don't want the house to catch fire from a shorted battery, I had to explain why putting batteries in a box like this was a bad idea. A couple of years ago, I got a kit from Radio Shack that introduces kids to electricity, circuits, etc. She knew about this kit, and got it out to ask me how a battery works. For the next hour she discovered how batteries work, how motors work, how a lightbulb comes on, and that some parts only work in a circuit one way, and she even did Morse code with a piezo buzzer.

That brought us to the moment when she could do it all by herself, help the electricity make a loop so the battery could do some work.

She just had to hook the alligator clip to the bulb and...

The electricity in the battery made a loop and the light came on.
She of course couldn't wait to show Momma.

Thursday, December 11, 2014

Finding Obsolete Parts: Furthering This Idea of a STHR

In a recent Post, I put forward the idea of a Strategic Thru-Hole Reserve of parts commonly found in kits made in the mid 90s to today. There's been some good feedback about this, so the next step is to discuss what comes next. I envision a website where people go to share what they have and what they need. Let's say I need a 2SC2166. I should be able to search for the part, select a person with the part, and contact that person to make some sort of arrangement to acquire the part.
Sound about right?

Wednesday, December 10, 2014

Operation Rock Garden Update

While I wait for #3 to bug me about her radio again, I'm working on my 10DE7 project.

Here's the skinny:
I took some parts that look like this:

and turned them into this:

and in the processed learned something about phasing.

Some project notes,
I did make the connection between taps 9 and 7 permanent, that is, soldered the wire in place. I made a short jumper with spades so I could experiment with places to put them on the taps. The first time, I soldered a jumper wire between pins 8 and 9, and didn't get the results I wanted. I thought for a minute that I had a bad transformer. I learned a couple of things in the process.

1. Autoranging digital VOMs can mess with your head. I kept getting jumpy measurements in the milivolt range, and it kept making me nervous. Verifying some readings with an analog meter really helped me settle down.
2. When dealing with AC transformers phasing matters. I should have realized from the schematic of the taps that the phasing a the bottom of one set of secondary taps would be out of phase with the top of the next set, but it took a little experimenting to figure that out.
3. When dealing with an unknown quantity, don't solder things down. I know better, but sometimes I don't do better.
4. Alligator clips for VOMs have their place.

I got to bed pretty late last night, so probably no shacktime tonight.

I have to think some more about plate voltages anyway.

Tuesday, December 9, 2014

Operation Rock Garden Phase One: Supplies!

I've decided to call my One Tube MOPA project "Operation Rock Garden." Because it is another project that involves a crystal controlled oscillator, I figured, why the heck not?

Phase one deals with power supplies. Not supply in this case, but supplies. There are three distinct voltages for this project, 2 different DC B+ voltages, and an AC filament voltage. Each one needs to be able to handle a certain amount of current as well. bBcause of this, I'll probably need a few solid state parts, like diodes and voltage regulators, for creating a rectifier circuit, or voltage doubler.

Step 1 of this phase is to light the filaments. To do this I need a circuit that can supply 9.7V at 600 milliamps. The easiest way to get there is to take the massive milsurp filament supply voltage I have, and series up the proper combination of taps to get as close to 9.7 as possible.

It came from a homebrew power supply for a Heathkit SB-102, and other than that, I don't know much about it, but I figure if I connect tap 8 to tap 9, and take my voltage from tap 7 and tap 11, I should have somewhere in the neighborhood of 9.45 Vrms, maybe a little more, because this primary is listed at 117 Vrms, and I'm around 120 consistently here.

Backside, showing taps.

I don't see this as an optimal solution, but it can handle the current, and the voltage should stay reasonably under the max. The supply has this lug sticking out of it.

The lug is behind taps 5 and 3. I think it's there so the core can be grounded, but I'm not sure the core needs to be grounded in the application I'm using it.

I will take advise in this matter.

Here's the plan for tonight when I get home from work:
1. Hook up the Transformer, ground (or not) the lug.
2. Construct tube base breadboard.
3. Go to bed. Light the sucker when I'm sure I have at least 9.4 Vrms, and after I've rested.

I'll be listening to 3579 KC while building, and the NoGA Twin Tube 80 will be standing by...

General concensus is that the lug can be grounded with no ill effects, and the filaments should be ok at that voltage.
We'll see if I can get 'er done tonight!

Monday, December 8, 2014


so the band was pretty well non-productive at 21-2200UTC yesterday. Noise floor way too high, and I couldn't hear anything over the whole CW section.
I tried calling CQ a few times, no spots.
I checked out the RBN for North American to North American Spots on 80m CW, and what was getting spotted seemed to be close in single hop (maybe) type contacts. Exactly what you'd expect when the Solar Conditions have the A index at 13, and the K is 4. RADIO BLACKOUT.
It was frustrating.
I did call CQ CBLA, and I did call CQ AWA, just don't think the propagation was there.
Maybe next time.
Fortunately, over night the conditions cleared up, and things could be shaping up for an interesting late evening on 3579. I can't guarantee I'll QRV, but now would be a good time:

Eastern U.S. Sector Infrared Enhancement 4
The map above is from, and seems to indicate that everything is moving off to the east, and the next system isn't off the west coast yet. I should be set for some contacts in the midwest, possibly the North East, if there's no snow/rain static.
Weather is supposed to cool down here. That's down to 50 tonight, and low 40s the rest of the week.
We shall see!
In the mean time, I have a regen to complete and a powesupply to ponder.
Hope somebody out there gets QRV tonight on 3579KC.

Sunday, December 7, 2014


Our brothers in the AWA are undertaking a noble effort right now in the realm of retro-innovation.
They are currently using homebrew amateur radio gear patterned after homebrew circuits of the 1920s and 1930s in their "2014 Bruce Kelley 1929 QSO Party and W2ICE Special Event Station"
Link is here:

We're not worth any points for these guys, but I'm calling on all CBLA members to attempt contacts with these stations during the last two hours of the contest. Several CBLA members are participating and have expressed their willingness to QSY to 3579 KC for this event.
Our mission parameters:
1. Contact 1 (or more) AWA 1929 QSO Party stations on 3579.
2. Submit a log mentioning the CBLA.
3. QSO with other CBLA stations immediately after the QSO Party.

#003 out, happy hunting!


Saturday, December 6, 2014

The Strategic Thru-Hole Part Reserve

On twitter the other day, @imabug lamented the demise of a favored component

The ensuing discussion was great, and I began thinking about the last tweet I made in it:

I made it as an offhand glib remark, and reference to the strategic petroleum reserve created during the 70s, but there was also a little "Ha-ha only serious" going on too. It would be nice to have such a thing. It won't be long before @imabug needs that J310 and the box is dry, what if we had that reserve.

I think of it as a sort of social network with two lists, one of stuff you have available, one of stuff you need. The list of stuff you have available you don't use in projects, just store well. Trade as you need to on your own terms.

Hand Full of Parts 2.

Thursday, G asked me about building her radio as soon as I was up and drinking coffee.

"Wouldn't you rather run some errands with me instead?" I asked. I didn't want to push radio on her.

"Ok!" She just wanted to hang out. That's cool by me too.

After we returned, she wanted to play out back again, and she did so, my wife and I could hear her singing outside. I stepped outside to keep an eye on her more better. As I crossed the threshold of the door the question came again:

"Daddy, can we build my radio some more?"

"Are you sure?" I asked.

"Uh huh!" she said, blonde hair bouncing as she ran to the shack.

We sat down and she informed me that she wanted to keep testing the capacitors while I stuffed holes and soldered. I laughed, and said "OK"
Things went well, and I invited her over to clip a lead or too. She liked that, I figured she would, since she loves cutting her own hair, why not give the radio a cut too!
The fun lasted about 20 minutes, and then G decided to practice casting with her Barbie fishing pole, so that's what we did next.
This radio has less than 20 parts, and it's already taken me longer than the SMK-1.
Something seems a bit more fun about it though.

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!