About rlankenau

I do software for work, hardware 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.

schematic

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.

components

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.

inductor

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.

phase-2-complete

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

book2-cover

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.

book2-inside-cover

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

book2-open
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.

book2-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.

FirstBook-Front

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

FirstBook-Open

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…

FirstBook-Cover

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.

FirstBook-Endpapers

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.

FirstBook-Spine

Shop Maintenance Day

FastPlot1
With the start of the new year, we’re planning to spend some time cleaning up the space. We’ll be out at the space all afternoon on January 2nd, so if you’d like to come out and help clean up, stop by.

Networking Basics (July 2014)

Come out and learn basic computer networking skills!

The topics we’ll be covering include:

  • Network addresses
  • Basic home network design
  • Physical interfaces
  • Wireless networking
  • Debugging basic networking problems

Continue reading

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.

Thursdays!

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.

Libraries!

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.

Classes!

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!

 

Electronics 101 (July 2014)

This is an electronics class for the absolute beginner – we will cover many basic concepts such as:

  • Current
  • Voltage
  • Resistance
  • Ohm’s Law
  • Power
  • Measurement tools
  • Breadboards – How to use them to prototype circuits
  • Circuit diagrams and circuit elements

Continue reading

Introduction to Arduino class (Arduino 101) Wednesday July 2, 2014

Workshop 88 is offering our introduction to the Arduino platform at our makerspace in Glen Ellyn. This class is for anyone (member or non-member) who wants to learn how to get started with the arduino microcontroller, regardless of experience with programming or electronics. Class attendees will learn how to configure their arduino programming environment, how to design simple circuits for interfacing with the arduino and how to write simple programs to control the arduino. What is Arduino, you ask? From their home page:

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.

If you need to get an arduino, please see the Workshop 88 Arduino Store. Sales from that store are fulfilled by amazon.com, and help support Workshop 88. Alternatively, you can order Arduino systems from several places, including Adafruit and Sparkfun. Both companies have lots of tutorials and howtos to get you started with Arduinos. If you’re looking for a local source to get Arduinos, try Trossen Robotics.

What you’ll get from this class:

In this class you will learn how to start programming in the Arduino environment including interacting with the inputs and outputs of the Arduino.You should bring: a laptop with the Arduino environment downloaded and installed, and your Arduino supplies.  Please contact us (info@workshop88.com) if you have any questions.Image credit: By Linuswiki (Own work) [Public domain], via Wikimedia Commons