Eugene

Control head stand

Necessity, as they say, is the mother of invention.

To address the need for a stand for the radio’s control head, I headed off to the workbench and dug up some scrap pieces of MDF (it was actually part of the packaging for a treadmill we bought a while back). Fired up the table saw to cut it to an appropriate size and glued/screwed the pieces together.

It’s a simple L-shaped base with the top part where the control head mounts to at a bit of an angle (30° according to my table saw)

4 screws provide the attachment point for the mounting plate from a goose neck stand. It was already on the radio and made sense to make use of it for this table stand. Here it is with the control head mounted.

A little bit of spray glue and some rubber kitchen liner on the bottom finishes off the stand. Not the prettiest thing, but it works.

Shack project ideas

Putting together the new shack has given me a few project ideas to work on:

Large dual display clock
~~Radio head stand~~
Window pass-through for coax and wires

I have a couple ideas in mind for the clock, including something powered by one of my *duinos, and something widget-y that can run on my tablet. Needless to say, neither one will be coming quickly since I have a lot to learn about doing both.

The control head for the radio doesn’t really sit all that well by itself on the table. There’s supposed to be a “foot” for it, but it’s lost in a box somewhere. I’ve got a few ideas to craft one out of some scrap pieces of wood lying around the garage. Shouldn’t be too hard to put something together that will work in the shack. Might not be pretty, but it should do the job.

The coax feed out the window to the antenna is a little less than optimal. The coax is sandwiched between a couple pieces of foam pipe insulation, which works but doesn’t look that pretty. There are window feed through units like the MFJ-4601 that would look nice. I was thinking it would be a fun project to make my own version.

Off to the workbench!

1N34A diodes

One of the projects I’ve been considering for a while is trying my hand at building some crystal radio receivers. Crystal radios are pretty simple and traditionally use a germanium diode as the detector element because of its low forward voltage drop.

Found several people selling 1N34A germanium diodes on eBay and ordered a batch of 100 a couple of weeks ago. They arrived in the mail yesterday, and today I got around to checking them out. The diodes themselves are unlabeled so there’s really no way to tell what they are by looking at them.

The forward voltage (V_f) drop of 1N34A diodes is supposed to be around 0.25V. According to my DMM, a random sampling of the ones I got showed a V_f of 0.29-0.30V. I figure that’s pretty close.

Measuring forward voltage drop of the diode

For comparison, the V_f of some random 1N4148 silicon diodes was around 0.6V.

Now to do some homework and see how to go about building a crystal radio receiver.

Shack relocation

We’re getting ready to move the shack out of the office/shack into what used to be the guest bedroom. It will still be the guest bedroom for the rare occasion we actually have people stay over, but it will become mostly the shack.

It should be a much better room for playing radio, especially from a temperature standpoint. The office tends to get pretty warm in the summer and especially so when the computer/heater is running as well.

The room is also a lot closer to the antenna and I’ll be able to have a much shorter coax run out to the antenna than I do now. The room is all prepped for painting, and we’ve selected what we think is a nice shade of blue for the room. A day to paint with primer and let it dry, another day for the paint and we should be ready to move the shack into the room.

Right now the plan is to have a long table with the radios against the inside wall.

The antenna feed point is just outside the windows, so I’ll bring the coax through one of these windows and run it along the walls to the radio.

This should also make it easier to use the back yard for antenna projects since it will make the feed line runs shorter and easier.

Morse code at 25 wpm

For a while now, I’ve been listening to Chuck Adam’s (K7QO) code course. It’s a good, methodical course that first takes you through each letter, with a cumulative test after every second letter. You get lots of practice hearing each letter by the time you get to Z. I’m starting to recognize most of the letters up to K now.

The course sounds like it’s recorded at somewhere between 15-20 wpm. For most people that’s probably plenty fast enough but it’s just slow enough that my brain still wants to count the dits and dahs and then convert to the corresponding letter rather than just listen to the rhythm of the sound.

What I needed to do is convert or generate a new set of files that plays the code faster. With a bit of experimenting at lcwo.net, I found that 25wpm was where my brain stopped trying to count dits and dahs, letting me focus more on the sound of each letter.

A little bit of searching brought me to a program called ebook2cw by Fabian Kurz/DJ1YFK, who also happens to be one of the people behind lcwo.net. From there, it was a trivial exercise to feed the answer files from Chuck’s code course into ebook2cw to generate a new set of audio files (OGG turned out to be about half the size of MP3) at a character speed of 25wpm and effective speed of 15wpm.

Here’s the shell script I used to generate the OGG files

#!/bin/sh
for file in *.txt
  do /opt/bin/ebook2cw -O -p -o `basename -s .txt $file` $file;
done

Do this in the directory where you’ve extracted the text files from K7QO’s answers file and you’ll end up with a bunch of .ogg files. Then copy them to the media player of your choice (if it can’t handle OGG files, it’s time for a new player). If you insist on MP3 files, just drop the -O parameter. The file names will have some trailing 0’s tacked on before the extension (chapter numbers automatically added in by ebook2cw) but it doesn’t affect anything.