About Russ Lankenau

I work on software, and do carpentry, electronics, and amateur radio for fun.

T-Kit 1380 Kit Build: Part 2

Today, I’ll be continuing my 80m transceiver build that I started in T-Kit 1380 Kit Build: Part 1.

At the end of the last post, the board looked like this:

The full board

The full board

Today I’ll be moving on to the VFO section of the board.  A VFO, or variable frequency oscillator, is the circuit that allows you to tune a radio.  This particular VFO is based on a Collpits oscillator, and can tune over a 50-70 kHz range centered on a frequency determined by the component values.  The frequency range shown in the image may seem a bit strange.  This transceiver can be built to cover that 50-70 kHz range somewhere near 3.5 MHz to about 3.75 MHz.  The short explanation is that the frequency we’re interested in is shifted by the frequency of the VFO to an intermediate frequency of 8 MHz, where we can do filtering and amplification at a single fixed frequency.  Since a lot of circuit characteristics are frequency-dependent, performance is much better if the components can be selected for just one frequency.


The majority of the components are supplied with the kit, so their values are fixed.  One of them, an inductor, I had to wind myself.  Since this phase required quite a few components, I decided I’d lay them out before I started.


Rather than start building immediately, I decided to wind the inductor first, so I could get that out of the way.  The instructions specified 28 turns of the green #28 enameled wire on the red toroid core.  I had to count the turns several times to be sure.


The inductance of the coil is dependent on a lot of things, including the material the core is made of, the diameter of the core, the number of windings, and the spacing between the windings.  Later on in the build, I tweak the range covered by the transceiver by adjusting the coil spacing.


From this point on, it was simply a matter of stuffing the board and soldering, as per the instructions.  The one thing I would have changed was the process for doing initial testing of the inductor.  They have you tack a couple leads to the pads you’re going to use, and then tack the inductor to those.  Unless your inductor is wildly off, you’re not going to be rewinding it, so I would have skipped that step and just soldered it in directly at the beginning.

The testing of phase 2 was relatively simple, because I’m using a frequency counter.  I just hooked up the frequency counter, and adjusted the spacing of the turns on the coil I mentioned before until the VFO covered the range between 4.470 MHz and 4.391 MHz.

I’ll talk more about it in the next post about the transmit mixer and filter, but that provides an actual range of 3.530 MHz to 3.609 MHz.  This includes the QRP CW calling frequency at 3.560 as well as W1AW’s code practice sessions transmitted on 3.5815.  It does not include the main CW DX window between 3.500 and 3.525 MHz, but I’m still working on getting my Amateur Extra license, so I’m not authorized for that part of the band anyway.


T-Kit 1380 Kit Build: Part 1

I won a T-Kit 1380 80m 3 watt CW transceiver kit at the WCRA Hamfest back in 2014, and it’s been sitting on my bench unopened since then.  I didn’t have my license at the time, but I got my General license about a week later. I decided that this summer was a good time to start building it. Here’s a link to one you can pick up if you’re interested : http://www.rkrdesignsllc.com/-13/

I have quite a lot of kit-building experience, but most of it is digital electronics, so this is probably the most complex kit I’ve ever built, both in number of components and circuit complexity.

If you’re not familiar with amateur radio, this kit will let you transmit and receive on the 80m band (between 3.5 and 3.75 MHz) using CW (morse code).

1380 Manual

The schematics in the manual are a bit low-res, but the instructions for assembly are very good.  My biggest complaint with the manual so far is that errata are supplied as a stack of papers inside the manual.  Some of them referenced parts this kit doesn’t use, so it was a bit of a chore to go through and update the instructions and update the steps by hand.

The assembly process is documented in phases, with testing procedures at the end of each phase.

Phase 1 is construction of the DC input circuitry as well as the keying circuit.  The keying circuit is connected to the code key, and disables the receive circuitry while transmitting.  Here’s the diagram for phase 1.

Phase 1 schematic

Phase 1 schematic

Here’s the board as assembled:

Phase 1 assembled

Phase 1 assembled

This is a pretty densely packed board, and the silkscreen suffers for it.  The manual gives pretty decent drawings of the section of the board each phase is concerned with, and this helps quite a lot.  You can usually locate a component by finding a nearby component you’ve already installed, or one whose silkscreen isn’t broken up by a pad.

Once this phase was assembled, there was a short test procedure to verify that it is operating correctly.  Essentially, I had to apply 12v to the 12v input, and then verify that R13 (the resistor in the center of the board, just between the two beige ceramic capacitors) read 0v while the key wires were disconnected (the white and black wires just under ‘J1’), and 12v while they were touched together.

I misread the directions and it took me a while to figure out what I was doing wrong (I was measuring voltage drop across the resistor, not between the resistor terminal and ground), but in the end, everything checked out.

The full board

The full board

As you can see, there’s quite a lot of work still to do, so come back next time, when I move on to assembly and testing of the VFO section!

Book #2


I couldn’t find an empty notebook this morning, so I made threw one together from printer paper and the remnants of the box my Amazon Echo came in.


This one is a quarto with two quires, simply sewn together with waxed linen thread and no glue.

The top stitch on the cover is a bit strange, but topology wouldn’t allow the initial pattern I was planning on. I might use a small ring or a bar to secure the top stitch the next time I try this format so I can avoid the strange fifth hole in the spine.

It fits nicely in a pocket, and the cover feels pretty sturdy. I could probably have creased the spine a bit more heavily to make it close better, but I’m okay with that.

First Try at Bookbinding

I’ve always been interested in bookbinding, but haven’t given it a shot until now. I followed these excellent tutorials by Sea Lemon on YouTube, and I think my book came out okay.

I made the case using black Tyvek for the cover, and 1/4″ masonite for the spine and front and back boards. I think it worked pretty well, and I like the way it looks.


I sewed the signatures together using upholstery thread, and the book opens up really well.


This is the view of the cover with the book open on the table. I cut the board for the spine about twice as wide as I should have, and I’m not entirely happy with that. I got a bit impatient once the text block was done, and just charged ahead…


Another issue with rushing ahead was that I used a bit too much glue on the endpapers, and they wrinkled a bit as they dried.


All things considered, I’m very happy with the way the book turned out, and I’ve got some different techniques to try next time.


What have we been up to this summer?

It’s been a bit quiet around on the blog this summer, but that’s mostly because we’ve been pretty busy.  I thought I’d put up an update on what’s been going on around the space.


We’re always out at the space on Thursday nights for our public meeting, so drop on by! We had a lot of fun last week playing with some Tormach stepper drivers that Tom M. brought in, but every week brings something new and exciting.


We’ve been doing a lot with libraries all over the burbs.  You might remember this thing that we built for Glen Ellyn Public Library back in May.  In addition to that, we also do a lot of classes and DIY fairs.

This summer, we ran events at Bloomingdale, Glen Ellyn, Indian Trails, Winfield, Lisle, Addison, and at Lake Park High School.  We’ve got even more events coming up in the next few months, at the libraries I mentioned before as well as Roselle and St. Charles.

Improving the space!

We’re currently updating the back room, with the front room next on the list.  There’s been a lot of great discussion about what to do with the front room, and we’ve got a team working on getting it all done.

Paul R. did a bunch of work to rehab Prof. Braino’s Enco mill, and it is now up and running.  We’re going to be offering a class to members this summer to get them up to speed on how to use the mill.


We’ve been a bit lax in getting classes scheduled, and we’re trying to address that.  We have a bunch of classes scheduled this summer, so check back for scheduling details once they’re announced.  Next up on the list are Electronics 101 and Basic Networking, both this July.

We’ve got a bunch of other topics coming up, here’s a condensed list:

  • Electronics
  • 3D Printing
  • CNC Machining with Shapeoko
  • Networking Basics
  • Running the Lathe
  • Linux Basics
  • Cloud Computing
  • HAMP (see this for more info)
  • Intro to Hadoop
  • Running the Mill
  • Using the RPi GPIOs
  • Arduino 101
  • Arduino Music

Let us know (info@workshop88.com) if you’ve got requests for other classes, we’ll see what we can do about getting them scheduled!


Audible Donation Box

Our local library recently asked us to help them out with their summer reading program, which is raising funds to support the Willowbrook Wildlife Center.

Here’s what I came up with:Glen Ellyn Public Library Token Box


When a patron turns in a book they’ve read for the summer reading program, they get a token to drop into the box.  Since the Willowbrook Wildlife Center rehabilitates native animals that have been injured, I thought that playing local native animal sounds would help create a connection between the program and the organization it is supporting.

Here’s what the box looks like inside.

Glen Ellyn Public Library Token Box Electrionics


The speakers are driven by an Adafruit Music Maker Shield run off of an Arduino Uno, using the Adafruit VS1053 library.  The token detection mechanism uses a high-intensity LED and a voltage divider, consisting of an 180 ohm resistor and a CdS photocell, to create an optical detector.  The voltage across the small resistor is checked with an analogRead() in a tight loop to detect a token falling through the slot.  Volume control is done through software on the VS1053, so I just hooked the sweeper on a 10K linear potentiometer up to a second analog input.  When a token is detected, I play a random sound from the SD card in the background while continuing to check the volume control.

Here’s the schematic and a breadboard layout.  I’ve just shown the control circuitry, as the Music Maker shield should be pretty easy to hook up.Coindrop SchematicCoindrop_Breadboard

All of the code, these schematics, and a Fritzing file are available on Github. Pay particular attention to the pin assignments at the top of the sketch if you’re using the Adafruit Music Maker board.  They are hard-wired on the shield, but Adafruit’s tutorial is based on their breakout board, which you have to wire to an Arduino yourself.

One thing I had to consider with this build was power.  I initially powered the box off of 4 AA batteries, and it looked like it worked great.  After a few days of testing, it started to act a bit flaky.  After being on for about 10 minutes, the speakers would just play static.  After some testing, I found that the supply voltage was too low, so I swapped in a USB power supply for the batteries, and it worked much better.  Since this has to run all day long for a couple months, USB is a better solution anyway.

We’re teaching a couple audio classes this summer, make sure to check back for scheduling details if you’re interested in doing something like this project yourself!


Bart Dring talks LinuxCNC and BeagleBone Black

Bart's Delta Router - Probably not going to be there on Saturday, but look at how awesome it is!

Bart’s Delta Router – Not going to be there on Saturday, but look at how awesome it is!

Bart Dring of MakerSlide fame is going to be out at Workshop 88 on Saturday, March 1 demonstrating CNC concepts and giving a brief talk about how he has constructed several CNC builds.  This talk immediately follows Arduino 301: Controlling The World, so come out for both! He has designed and built many great tools, such as a laser cutter, several types of 3D printers, including delta style printers. One of his most recent creations is a delta-style CNC router. Very cool! We look forward to having Bart out at Workshop 88 to share his expertise.

This event is FREE and OPEN to everyone! Please come out and bring a friend.


Ham Radio at Workshop 88

There’s been a lot of activity around amateur radio at Workshop 88 in the last few weeks.

The biggest portion of that was organized by Eric S. and Paul R., who had a table at the WCRA Mid-Winter Hamfest. Andrew M. helped with the table as well, and Tom M. and I also stopped by.

Paul and Andrew man the table at the WCRA Mid-Winter Hamfest

Paul and Andrew man the table at the WCRA Mid-Winter Hamfest

We’ve had a lot of electronics gear donated over the last year, and most of it just wasn’t being used. We were able to sell quite a bit of it to people who will actually get some use out of it, and raise some money for Workshop 88 in the process.

In addition, we’re talking about organizing some sort of study session or workshop to help people get their start in amateur radio. We have several very knowledgeable hams who are members, and a number more who are interested in getting their license for the first time.

If you’re interested in radio or want to find out what it is all about, come out to a public meeting night at Workshop 88 (every Thursday at 6:30) and introduce yourself!