- 2022
- Aug
- 7
The Hallicrafters S-41G Skyrider Jr.
I’ve been looking for an AA5 “Shockbox” radio for a while now, but these seem to be getting kind of rare, which is odd considering how many of those things were made. So I’ve decided to instead look for an older multi-band unit. While this one wasn’t exactly what I wanted, it was cheap enough that it will work until I find a better example.
The Hallicrafters S-41G “Skyrider Jr.” was introduced right after WWII as a low-cost entry level receiver, alongside the company’s Echophone EC-1B which is electrically and mechanically identical. This unit lasted for a few years, and was replaced with the more common and more familiar S-38 line, which lasted for 6 models (S-38 through S-38E.)
This unit is in “acceptable” condition, and is complete with original knobs, a usable face, and limited damage to the chassis. It was purchased for $25 on August 6th, 2022 at the Columbus, Ohio hamfest.
When I first saw it, the friend I was with said “That looks like it sat around in a shop for years as the shop radio.” Turns out that was correct, the gentleman that sold it said it was in his father’s shop for years, but his father was unable to answer any questions about it, being in a state of mind that didn’t allow for much these days. That’s kind of sad to know I won’t be able to get any history, but that’s how it usually goes with these things.
First thing I did when I brought it home, of course, was to give it a quick lookover and then plug it in. Unsurprisingly, it came right up, and after getting the crud of the ages out of the switches, I was able to receive one of the strong local AM stations without any antenna connection. It must still be decently aligned.
The radio had the “science fiction squeal” as you turned the dial. Bad AGC capacitor, but that’s expected. Then the volume started dropping. Grid coupling capacitor was leaky and slowly allowing voltage through, cutting off the tube. I was about ready to turn if off, as I don’t want to destroy the tubes when it went POP and smoked. Capacitor blew out. Since the volume didn’t change, I expect it was the one across the line. But I rapidly pulled the plug anyway because it was shown to be working and that’s what I needed to see.
What’s a good initial showing without tearing the bottom off and baring the goods to the world? So that’s what I did next, and probably should have done first.
There were those big orange replacement filters. That was visible from the back, so no surprise. These were 450VDC capacitors with a 1974 date code, and decently installed. The voltage was far too high for the rectified line, but there are multiple schools of thought on this. One says go to the max, others say keep the voltage near the working voltage. The thought behind this is if you don’t give the capacitors their rated voltage, they can lose their ability to be a capacitor, and will try to “reform” and become capacitors again every time you apply voltage. I’ve always followed that rule, so a B+ of 150VDC probably would net a 200WVDC capacitor. In any event, these will go and get replaced with modern (and smaller) capacitors. Since these are nearing 50 years old themselves, it’s probably time regardless.
The other changes were the addition of a new line cord (sans the probably long dried out grommet in the chassis it went through) and a phone jack across the pin terminals originally placed by the factory. Not bad, usually these things are just a mess inside.
What’s going to happen next is the finding of a schematic. While I’d like to get the original Riders or Sams set for the radio, that may be difficult. There are a number of offerings online, so it’s just a matter of finding one that’s not a honeypot and downloading it. Then, the process of determining which parts need to be replaced begins - but that’s probably a job for this winter when the snow flies and the days are short. But check back in a few months for more on this set.
- 2022
- Aug
- 7
My haul from the 2022 Columbus Hamfest
I really need to stop doing this. What am I going to do with these things? HOARD THEM!
- 2022
- Aug
- 7
Pictures from the 2022 Columbus Hamfest
This year’s show was a bit muted - the sky threatened rain all day, and it did rain in several locations around the city. Fortunately, it held off at the Aladdin Shrine Temple, but still kept things low key. More vendors showed up as the morning went on, and the inside of the building was still fairly well packed as usual.
There was enough to keep me and a friend busy for almost 3 hours, and we found ourselves going back and forth as new people arrived. A few things I probably should have walked out with, but I have to be kind of choosy because I have too much junk already. Oh well…there’s always Findlay in a month!
- 2022
- Jul
- 5
Columbus, Ohio Hamfest 2022
The Columbus, Ohio Hamfest is happening this year on August 6th, same location as last year. It’s usually pretty good, and I’ve always pulled an excellent deal or two out of there.
When: August 6th, 2022. 8AM to 1PM or so
Where: Aladdin Shrine Temple - 1801 Gateway Circle, Grove City OH 43213
Homepage https://aladdinshrine.org/hamfest/
ARRL Ohio Listings http://arrl-ohio.org/hamfests.html
- 2022
- Jul
- 4
Unusual and interesting light sensors
There used to be a place in Dayton, Ohio called Mendelsons. This was a giant surplus house in one of the old Delco buildings on 1st street, near where the current Dayton Dragons field is. In 2021, the store did it’s final sale and closed.
There were several bulk bidders, including a place in Mansfield, Ohio called ESL Surplus. One of the things in the lot they bought was these unique little sensors. I had purchased a number of these years ago from Mendelsons, and I always wanted to get some more - unfortunately, with the world being afraid to open their door for two years, that didn’t happen. When the store went out of business, I figured that was it.
Fortunately, I had the chance to get more this past weekend.
These are tiny solar cells embedded in a plastic bubble, with an output of about 0.5V each - just enough to amplify and detect. I have no idea who made them, or when they were made - the discolored lens suggests they’ve been around for a while, quite possibly the 1970s. There’s no marks or other ID on the plastic housing - perhaps these were made to order and never used?
I’m not really sure what I’m going to do with these devices, but they go in my parts stash as, at minimum, an unusual piece of technology from years past.
ESL Computers (and surplus) URL removed
Mendelsons (archive) https://web.archive. … 30/https://meci.com/
ESL does not appear to exist at this point. Their website is now a malware pot.
- 2022
- May
- 25
Breezeshooter’s (Butler, PA) Hamfest cancelled for 2022
Unfortunately, it looks like the Butler, PA (Breezeshooter’s) Hamfest has been cancelled this year.
http://breezeshooter … -2-day-hamfest-2022/
Perhaps I’ll see you at the Mansfield, OH show instead.
http://www.arrl.org/ … d-summer-trunkfest-1
Mansfield Mid Summer Trunkfest
07/09/2022
Richland County Fairgrounds
750 North Home Road
Mansfield, OH 44901
ARRL Hamfest
Talk-In: 146.940 - PL. 71.9
- 2022
- May
- 23
Pictures from the Dayton Hamvention 2022
After being closed for two years, the amount of goodies that showed up this year didn’t disappoint. There was so much stuff it was hard to see it all in one day, and I missed some photos I should have grabbed. I probably should have went Saturday as well, but one day of this stuff is plenty - and there’s more shows to come.
It was hard to resist dragging junk home, but I only wound up with one large piece of equipment. It appears to be fully functional, so I’m happy with the $20 I spent on it. The rest of my purchases were books and tubes and some odds n ends, nothing really major.
As always, this was an experience from the sheer amount of stuff that shows up. Hopefully, next year will be just as good - see you there!
- 2022
- May
- 22
An EAS-1 Emergency Alert Decoder
My one “big” purchase from Dayton this year, this EAS (Emergency Alert System) decoder was designed for the broadcast industry. It listens to terrestrial radio for the SAME data burst that indicates some agency (such as NOAA) has issued an alert.
This device is capable of spitting out decoded text, audio, or other formats useful for the broadcast industry, but it also has serial outputs. I plan on using this device in conjunction with a Pi that listens on a serial port, and takes the decoded text and emails it to interested parties. It’s a bit overkill, but I like being able to do this myself and not rely on someone else’s connection.
What really makes this device unique is that it was made here in the USA, is still being made, and is made by a company that’s based right here in Ohio. It’s fully supported and all data is downloadable. As soon as I can get it programmed and get a few sources for it to listen to, it goes into service.
- 2022
- May
- 4
A potato of a board.
I was laying out a power distribution board and happened to show the render to someone. They said “That’s a real potato of a board.” Thus, the line of “Power Potato” boards was born. I was even able to find a “Potato Block Letter” font to complete the tuber theme.
- 2022
- Apr
- 27
Revisiting an old project with new ideas.
A few years ago, I wanted to create a device to measure the current being consumed in my home. This isn’t a particularly new idea, especially with rising energy prices - having some sort of feedback on what you’re doing can help reduce unecessary useage.
There are a number of devices and systems out there that already do this, including some that can access the information from an electronic meter connected to the mains supply of a house. These are meant for Joe and Jane Average, and often rely on proprietary backends to do their work and don’t expose any kind of data that can be placed into a historian. If they do expose data, then again, you’re relying on someone else’s computer and your internet connection to provide said data, and those systems may change or go away at any time.
The goal, then, was to create something that could provide a universal data output that could be connected to any device capable of reading said output. An analog voltage from an analog circuit was chosen, both due to the instantaneous response, the the availability of cheap current transformers, such as the one in this picture. This device simply snaps around an incoming AC line, and provides a physically isolated output of either (in this case) current, or voltage.
This solves the biggest problem of how to get the measured current out of the fusebox without cutting AC lines. I’ve chosen voltage output devices for this particular project, and since the voltage output is small (usually in the mV range for full scale,) the first thing to do is amplify it a bit. This is accomplished with a standard op-amp circuit with a gain of 10-20, depending on the current transformer chosen. This also gives a bit of isolation, but that’s not really necessary at this point.
Next is how to feed this into something that a hobbyist would have access to. Measuring DC is much easier than measuring AC with commonly available microcontrollers, so the problem to solve is converting this signal to DC. This can be done with a simple bridge rectifier circuit, but I prefer to use something I found years ago in one of those “Big Books of Circuits” that TAB Books used to publish. The circuit in question is called a precision rectifier circuit, and the goal is to output a signal similar to the input, while minimizing losses. It works well enough, and a small capacitor and resistor on the output gives a decently filtered DC signal with fast-enough response.
While I’ve built this circuit on bread- and protoboards many times:
(I’ll put the image here when I can make it a decent size)
I decided to lay this one out on a board.
The board turned out ok, but now that I have more experience with layout, I’m not really happy with it. But it works, and all of the germanium glass diodes used as rectifiers provide a rather cool look. I’m going to go with shottky diodes for the next round, simply because germaniums are getting harder to find and the shottkys are better at handling even the low slew rate of a 60Hz signal.
Two remaining tasks at the time were to test the board and it’s output, and to choose a microcontroller platform. Testing was easy, the project had originally found a home at a former employer as a monitor for air compressors - the company wanted to run tests over the weekend requiring compressed air, but needed to know if the compressors were to become locked in an on state (which would subsequently result in overheating and damage.) I did the initial testing in the fusebox for the compressors, and was able to translate the resulting DC output into a correct current draw. The employer then lost interest as it was revealed this was going to cost more than nothing to fully develop. I had to abandon the project as the business slowed and let people go while the sky was falling.
For the next round, I’m planning on trying out some of the new microcontroller options on the market, especially the Raspberry Pi Pico. This is a fast, dual-core Arduino-like that’s extremely inexpensive, and has an Ethernet onboard option offered by a third party. My original design choice was to use an ESP8266, but that didn’t go well, so was abandoned. Read this entry for my misadventures with the ESP controllers: https://pygg.xyz/pro … of-cheap-technology/. A new board with multiple channels of input is in the works, and will offer a better onboard ADC as well as some user amenities like a display. Stay tuned for the next update!