Category Archives: Amature Radio

40 is dead, long live 40!

I had mentioned a little while ago that I was planning to work on a 40 meter receiver followed by a 40 meter transmitter. This is still the plan but there was a snag that I thought was worth mentioning, particularly for those new to Amateur Radio or to homebrew radios.

The 50 Ohm 5Watt dummy load I built last month, and most of the diagnostics tools I have been building recently for that mater, came from the book QRP Basics, second edition by Rev. George Dobbs G3RJV.  Another project in QRP Basics is the 40 meter (7-7.3 MHz) receiver I planned to build. The receiver in the book has some additional modifications to the RF (Radio Frequency) input section, an RF band filter and a modified tuner that replaces the VXO (Variable Crystal Oscillator) with a VFO (Variable Frequency Oscillator.) The VFO has a wider tuning capability, it can tune the entire band rather than 600-700kHz of the band centered on the crystal frequency in a VXO.

First go at the 40
First go at the 40

The diagram made sense, for the most part, and I could see and define the separate sections of the receiver. The challenge was my minimal knowledge of circuit diagnostics.

I got the AF (Audio Frequency) amplifier working fine. Likewise the AF input filter. It was the RF side of the equation that was giving me trouble.

It was clear that I needed to improve my skills in diagnostics so I picked up a copy of Experimental Methods in RF Design by Wes Hayward W7ZOI, Rick Campbell KK7B, and Bob Larkin W7PUA, here after referred to as EMRFD, with hopes that it would give me the information I need to better approach the radio build projects I have planned. Just 8 pages into the first chapter and it is making me think and work!

The receiver I originally planned on, and started, was from QRP Basics. A stripped down basic variation of this receiver is the first project in EMRFD starting on page 1.7. The nice thing is that this design has fewer parts, a VFO that uses a LC (an inductor capacitor network circuit) tuner that gives you the whole band, approximately 6.9MHz to 7.5MHz, best of all the complimentary transmitter is also in the first chapter.

EMRFD makes you think more about what you are doing and requires you to actually learn about each circuit segment. The first chapter outlines a very modular approach, the building blocks of the larger picture but in reverse. Start big with simple broad strokes, then narrow it to more manageable chunks, then further and further as you go. It encourages the start simple philosophy to get it working, then refine individual areas as you go.

The book goes on to give a more in-depth look at specific RF circuits, not a list of projects though, it gives you an idea as to how various RF circuits may be improved or incorporated into a design to improve the over all performance of a project. It seeks to instill an adventurous and experimental approach to RF design. Rather than a “you must” approach it is a “hay, what if” way of looking at overcoming the challenges in RF design work.

QRP Basics is a great book, and it covers homebrew radio, but more as a kit builder and operators guide rather than a circuit designers/builders guide which is what I am really looking for right now. I don’t see myself getting an electrical engineering degree, but I do need to up my game in RF circuits and basic electronics knowledge, big time.

Second go at the 40
Second go at the 40. Parts poked into an anti-stat mat grouped by receiver segment, RF to the left and AF to the right. Look at those sexy toroids!

About the title of this entry… Yesterday I completely disassembled the receiver I started two weeks ago and restocked all the parts.  The 40 is dead. Today I poured over the schematic of the EMRFD design and began picking the parts and planning the layout. Long live the 40!

While part of the goal of EMRFD is to use whatever parts you have lying around, I was going to have to make some weird choices in parallel and series multi-value/component clusters and I am not yet up to the challenge of re-designing things like LC tuning circuits so it was also shopping list time today as well. With a bit-O-luck HSC will have the variable capacitors, resistors, and jacks I need finish this project quickly.

My neatnic brain is not ready to go with “ugly” construction so my boards, at least for now, will be done on perf-board.  I know “ugly” is a perfectly acceptable prototype process, and has benefits in VHF/UHF/SHF frequency applications, but I am working in HF so a little attention to not building in inductive ground planes should be fine. My aversion to “ugly” includes using two 100 ohm resistors in series when I don’t have a 200 ohm resistor. I’m sure I will get over this affliction at some point, I’m just not there yet. In the mean time I will spend a little more time on the layout phase.

Until tomorrow the 40 is on hold. The plan is to have it up and running before April. I have a lot of projects to do this year. 😉

73,
~KK6GXG

ETA: 2015-04-03 The new project page for the EMRFD 40 meter receiver is here.

Flickr photo set for the 40 meter receiver

My first homebrew toroid inductor. Aint she purdy?
My first homebrew toroid inductor. Aint she purdy?

Learning CW Online

Cheap USB mouse
Cheap USB mouse cost $7 new from Amazon or any spare junk drawer mouse will do.

There is a neat site Learning CW Online or LCWO.net I am just starting with.  Since I am just starting with them I don’t have a whole lot to say about the site, but, it did spark a short project idea.

ETA: For a bit of history on CW and the Telegraph in general take a look at this page a reader of this post replied with. Thanks Corrine.

The site is a a commercial text messaging advertising site I don’t know anything about but the Telegraph and CW history is interesting. CW is the first digital mode, was a commercial enterprise, and was the original text messaging system with number of character limitations shorthand codes, and abbreviations. All it was missing were emojis.
/ETA 11/20/2021

LCWO has different sections for copying code and for transmitting code. The copy side is easy, just listen through the speakers on the computer or headphones. Transmit requires action, you need to key something, usually the left mouse button. I have a touch pad and not a mouse. Besides, a mouse doesn’t have the feel of a straight key (SK) and that’s what I will be using on the radio…

Enter the idea… a USB cw key! I’m cheap and more homebrew so I came up with an incredably simple USB mouse mod that allows me to use the key with any site or program that will allow you to key by clicking on a virtual key.

All I did was open up the mouse ans solder two wires to the left mouse switch and run those wires out the side of the mouse case and tie them down to the binding posts on the straight key. Now the key is parallel to the switch. You can still use the mouse, and you can use the key too.

I still need to do one thing before this project is done. I need to install a jack in mouse so I can easily unplug the key when I just need a mouse.

Helpful Hint: If the mouse keep sliding around while you are trying to use the key, just line it up with the on-screen button and slowly pick it up and turn it on its back. This will stop it from tracking.

Here is a link to my progress shots on Flickr.

USB mouse/cw key with jack

ETA: The jack has been installed and it works great. 

Interests In Phase

My last post was full of projects I have been working on all year, an annual wrap-up as it were. If you payed only slight attention to the post you would probably notice that nearly all of the projects were woodworking projects. If you went back to posts and social media of late 2013 and early 2014 you would find that most references were to amateur radio, go back a little further and there was a nearly three-year stretch of mostly aviation mechanic stuff.

What does it all mean? Does this guy flit around from interest to interest and never finish anything or stick with anything? No, and yet sort of.

When you have a wide range of interests it is difficult to work within the scope of all of them at once. Often times projects will spur interest or rekindle interests never pursued when they encompass something “new.” Take radio for example. I have been doing radio stuff since the early 80s. I was into CB back then and later with Search and Rescue that continued. When working in towing I did a lot of auto-electric and radio work. One of the things that got me into CB was a desire to work short wave. What brought radio back into phase for me was aviation.

My personal interests in aviation mechanicing are widely separated, and at the same time not so divergent. My greatest personal interest is in restoration of early aircraft, around 1910-1930. In the latter part of this radio was just making it into aircraft. To work on radios in aviation you need an FCC General Radio Operator License (GROL) as well as FAA approval. As an A&P student I found that while the FAA mandated curriculum lags behind current technology (some stuff from the 40s is still required knowledge) it is still much further ahead of the period I am interested in.

Beyond my personal interests, I need to be marketable as a mechanic to get a job. An A&P mechanic with an FCC GROL with a RADAR endorsement seems to have an advantage to me. To get the commercial licenses it made sence to get an education on the subject matter. I had just finished two years of A&P school and the thought of starting a new major and taking on more student loans seemed like a bad idea. Re-enter amateur radio. Now, 30 years after my initial desire to get  a ham license, I have my Amateur Extra Class license. 

Woodworking also ties into this mix. Hams don’t just talk on the radio, they build them. They build structures to contain them, they build a lot of stuff. Well, some do anyway. It wasn’t just radio that pushed me further into my woodworking zone though.

Back in the early 90s I rebuild my great-uncles house after he passed away. I have been doing odd construction related stuff for years but this was my first big project. I had to learn a lot before starting various trade work, and I did learn a lot and I have put it to good use over the last few decades. I like wood working and construction, it is very satisfying.

So with this back ground of making stuff building my own airplane seemed like a good idea. Many of the early aircraft were wood structures. Even the largest airplane ever built, the Spruce Goose was a wood structure airplane. This is how woodworking got me into aviation maintenance.

By now I bet a few things are clear and some are clear as mud. All of my interests tie together, somehow. Even homesteading ties to my interests. Some more obvious than others.

So, back to interests in phase. The desire to work on projects in various areas of interest all the time is always there. The needs of the time dictate what specific areas need the most attention at that moment. I can keep a few things floating at a time but not everything.

One of my current goals is to do stuff from various interests more often, mix them up a little more.  I have a tendency to go all-in when phase shifts and one skill becomes more timely than the others. Subsequently, it looks like I’m often distracted by another shiny. If I am truly honest with myself there is a degree of truth to being distracted. Fortunately it is distraction by a subject/project/research that I most likely would have ended up doing anyway.

~FlyBoyJon/KK6GXG/A&P/…

50 Ohm 5 Watt dummy load

I have been wanting to build a ham receiver and transmitter for some time but hadn’t found the right project, well now I have. A low power (2-5 watts) in the 40 meter band (7 – 7.3 MHz) for CW (Morse code.)

One of my reasons for this choice is its a good quality radio with tuning of the full 40 meter band and no crystals. I also need to get cracking on learning CW so this seemed to fit right in.

Anyway, I want to get started on the receiver next month so I am working on a few tools to work with and test the radio project as it moves forward.

I have five tools to build, all of them are relatively easy to build and don’t have many parts they are a Peak-peak RF probe, an RMS RF probe, an RF sniffer, a 50 Ohm 5 Watt dummy load, and an RF power meter. Today I built the 50 Ohm 5 Watt dummy load.

The dummy load is the black cylinder attached by a very short coaxial cable and connector. The guts of the load are twenty 1,000 ohm 1/4 watt resistors all connected together in parallel. One end of the resistor ribbon is connected to the shielding of the cable and the other end to the core wire. Then the whole thing is rolled up into a cylinder.

The roll of resistors is covered by a sleeve of heat shrink to insulate it from the copper casing made from two 1/2″ pipe caps and a short piece of pipe. With the resistor bundle insulated I put a small zip-tie as a strain relief on the cable. Then the copper tubing and caps are closed up and another piece of heat shrink is put over the whole thing holding it all together.

I futzed around for a while to make a cylindrical cage for the resistors and just wasn’t working out. The only reason I wanted to do it that way was to make in look a little classier… on the inside… anyway, now it is all done and works great. I can now test low power radios, up to 5 watts, without an antenna or transmitting spurious signals or doing damage to the radio. Yay!

50 ohm 5 watt dummy load

Acceptable Tech Level

Today was a great day. I got up early to head out to the Saratoga Fire Station to take my Amateure radio Extra class exam. I am happy to report that I can now use the temporary callsign KK6GXG/AE, for those not in Ham radio, that means I passed. Needless to say I was stoked to reach this, the highest level of amateure radio licence. Lots of plans are piling up for radio projects on my desk/bench so there will be reports on those to come, this post however, is not about radio.

Water Grinder & MotorAfter the test the wife and I went to the De Anza College Flea Market. I found something I have been looking for for a long time, a sharpening stone (wet stone) grinding wheel. What I had been looking for was a manual, or hand-crank type that can be easily adapted to a foot-treadle or bow-spring drive. The one that I found was attached to a motor via a reduction pulley-and-belt system, though in honesty I didn’t realize how low the reduction was at first.

My initial reaction was to remove the motor and adapt the wet-grinder to a manual power source right off the bat. After looking up the patent info on the motor and seeing what it was originally intended for a story began to emerge on the origins of this particular assemblage.

The board everything is mounted on does not appear to be that old. The dimensions are modern, making the mounting 2 x 12, at oldest, from the 60s. The mounting hardware is a mix of 50s and contemporary. The casting and markings of the wet-grinder suggest that it was cast in the 1920s to 1930s. The patent date of the motor is from 1926. This particular 1/4 HP motor was designed for washing machines of the 20s and 30s. A newer motor was produced after the war and the model and frame numbers on the data plate suggest that this motor was produced in the 30s.

20140607_191708The story I have come up with is that these parts were cobbled together in their current configuration some time the 70s from parts and used regularly for a significant time as such and eventually shelved in a shed where they had been sitting for at least a decade.
I ended up doing a mechanical teardown tonight. I was planning on getting started with the electrical teardown and testing tomorrow. For the most part this was an inspection teardown. I didn’t do any “repair” although I did fill the water reservoir with a rust remover to begin prepping it, and to see if it still holds fluid. I didn’t detect any leaks and we will see if it develops any overnight.

20140607_191718The plan is to deal with the mechanical and electrical as completely separate restorations. The mechanical is the primary because I can still set it up as a manual wet-grinder and begin using it.
I have a number of sharpening projects that need to get done soon and this would be a big help in speeding things up. Once rust is abated I think a couple of coats of iron oxide primer followed up with a couple of coats of oil-based paint should provide a sufficient level of protection.

Once the mechanicals are all taken care of I will spend some time on the electrical motor. At this time I have no information on the motor other than what’s on the data plate.

20140607_114338So why the title “Acceptable Tech Level”? one of the reasons I wanted a manual grinder was to further the off-grid hand tool goals I have been trying to work with. With this particular configuration I can easily swing it over to manual and with the motor most likely being from the 20s-30s it falls into my era of interest in aircraft and is also from around the same time as several of my inherited and acquired hand tools meaning it fits right in with many of my vintage tools. The important part is that it CAN be used with manual power.

Until next time…

☮ ♥ ✈ & 73,
~FlyBoyJon / KK6GXG

Voice Communications

20140518_105456You may have noticed this placard over my shack bench desk. I didn’t have this made for me, I inherited it. It was my mom’s placard, traveling with her throughout her various offices at Amdahl/Fujitsu.

Mom had a long relationship with telecommunications throughout her life. My earliest memories of my mom working were of her plugging the switchboards at an answering service. She made a second career for herself as a bookkeeper for many years but returned to switchboard communications where she stayed the rest of her life. She was a very talented communications operator and supervisor.

I didn’t spend huge amounts of time at the answering service growing up, but I was there enough to learn about tip & ring, how switchboards worked, the old cord-boards, and what the miles of wire behind them were for. I was lucky I suppose, there was a phone company technician swinging lines fairly often while I was there. In some small way I think that experience influenced my desire to go work for the phone company, which I did for a short time.

20140512_170250Looking at mom’s placard this morning I got a little nostalgic and started thinking about how I have been involved in communications, at least peripherally, as long as I can remember. In some way it seems as though I inherited more than just the placard. Communications seems to run through our veins.

As it turns out mom wasn’t the only family member in communications. My grandfather Robert was in communications while in the Navy during WWII. My great-uncle Allan was a signalman in the Navy as well during the war (WWII.) Allan also worked for a military aviation contractor working with navigation and avionics equipment after his hitch ended. These two related fields seem to be hereditary in my family. Robert had some connection to aviation as well, but the details are sketchy.

I never met my grandfather or spent any time with my great-uncle when he was alive. I found out about their experiences with communications and aviation while doing genealogy work after my mom passed in 2006. Like so many other vets, they didn’t talk about these experiences with their families.

Radio and aviation have always been comfortable places for me. I feel good doing these things. Even when I am frustrated or stumped, I can always figure things out and learn new skills. There are vast communities to get involved with for both, but they also provide space for solitary practitioners looking for some alone time. Both fields also seem to interact easily and many skill sets translate from one to the other well. Both also are very broad in scope, they have many sub-sets of interest to keep an interested party busy with a seemingly infinite variety of new things to learn and do. I am very grateful to be a part of both fields and I look forward to years of continued participation and sharing in both of these communities.

☮ ♥ ✈ & 73,
~FlyBoyJon / KK6GXG

CW Oscillator

The shack/radio bench is rapidly evolving. I have been working on several radio projects, most of which have been relatively small. The most recent project is a CW (Morse Code) practice oscillator. It allows me to practice sending code while I learn.

I had built a transistor based oscillator which worked okay but the tone wasn’t that stable, or loud enough to be that useful. I had a drawn up a simple transistor amplifier that I planned on adding to the circuit board, but the design is still less that optimal from a stability standpoint
After building the transistor version I decided to try an IC (integrated circuit) based oscillator. The tone quality, stability, and volume are much better than the transistor type. I built the oscillator on a breadboard to test the circuit out and make sure everything was in working order.

After checking everything out I started laying it out on paper the way I would actually wire it all together on a proto-board.

Everything worked great so I was ready to get to the next phase of the project, building the housing for the whole thing
The plan for the case was to build a wooden box with as much of a vintage (read steampunkish) look to it so it was time to move operations from the shack/radio bench down to the workshop.

First up was to design a basic box. I chose Douglas fir for the frame pieces and mahogany plywood for the panels.

Since I was going for the steampunk look, brass, lots of brass. Everything was stuff I had around the shop so there was no waiting. More importantly, I have lots of the stuff so I can experiment a little.

 

The box was all hand cut and assembled. Everything is held together with glue though I did use brass pin nails for accent. The brass speaker grill doubles as a retainer for the analog acoustic speaker. I didn’t want to use the cheap plastic one in the project. The sound just isn’t the same as the paper speaker.

The other end panel was going to just be wood and nails, but I decided to go with an accent that would double as a way to open the panel. This panel needs to be removable because the battery is on this end. I went with a key hole on a whim, it just looked right. It was a bugger to hand file the whole plate but I think it’s worth it.
The box took two days to plan, cut out all of the materials and to assemble. The brass work was done the second day as well. It took a third day to apply the several coats of linseed oil that I used for the finish.

Once the box was all done and the finish was dried it was time, on the fourth day now, to plan out exactly how I was going to install the guts.

I know this was not a very thoroughly planned project. I planned out the electronics pretty well, but the case, well that was very much an on-the-fly thing.

Any way, back to the timeline, with all of the case work done it was time to relocate back to the shack.
Back in the shack I worked out the bugs in case design, well, I developed the work-arounds for the issues that arose from the case design. What can I say, one of the reasons I am doing this project is for a learning experience and I have learned a few things about project design, and project housing design in particular.

There are several things I would do differently if I were to do this project again. One would be to reconsider trying to stick mostly with hand tools. I could have saved myself a ton of time had I built the frame using my router.
I could have routed a single channel strip on the router and just cut the pieces and mitered it all together.

Another change would be to use tiny screws to hold the panels in. I would have had much better access while installing the guts.

As they say, hindsight is 20/20. Lessons well learned and worth learning.

Below is a short video of the oscillator in operation.

Until next time,
~FlyBoyJon

I’m a multi-bench kind of guy

20140317_142358While I was in A&P school almost everything I posted was, of course, aviation related. Since I graduated a lot of my time has been spent working with wood. One of the biggest projects, literally, was a new woodworking bench using traditional joinery and oak draw-bore pegs to tightly secure it all together. (later I added a crochet at the left front that was attached with 2 lag bolts which constitute all of the metal on the bench)

But wood isn’t everything. Back in October I took my first Amature Radio license test and earned my Technician class license, last month I took the General class exam and earned my General class license. I’m used to doing computer hardware work and in the past I did a little electronics work so I was familiar with some of the stuff involved in radio, but not a lot.

20140518_130113Back in the 80s I was into CB radio. Later in life when I was working in the towing industry I did a lot of electrical work on our tow trucks which included the radios, and of course, installing my own car stereos since I could drive. These other activities made me a little familiar with Ham radio, but only in a very cursory way. What pushed me to finally do what I had wanted to do for decades was learning more about aircraft radios in A&P school.

Now my “electronics bench” is shifting from computers to radio. I have some basic electrical diagnostic tools and a full compliment of basic hand tools, but I am lacking in some of the basic radio diagnostics and bench-tools. As with woodworking and other trades, what better place to cut your teeth than making some of your own tools.

Dummy Load
Dummy Load

This week on my radio projects list I had one bench tool, a dummy load. For those who may not know, a dummy load is what you would connect a radio transmitter to, instead of an antenna, to conduct a variety of bench tests, usually power output related. Not having a load while transmitting, an antenna or dummy attached, a radio can burn out; basically you are generating a lot of “power” but not giving it anywhere to go. While testing you don’t want to connect an antenna because you would be transmitting all of your tests on-air wasting air-time and occupying a frequency someone else could be using for communication.

So thats why a dummy load, now for the what. A dummy load is used to dissipate RF energy, that would otherwise be radiating from an antenna as radio waves. The load can be dissipated through a resistive material as heat instead of radio signals.

20140430_131228An easy way to accomplish this is to use a resistor with relatively low resistance and that can also handle high power loads. Another criteria is that it shouldn’t radiate, or leak, spurious signals.

That last part becomes tricky because you can’t use resistors that are made from coiled wire, normally the kind used in high power applications because the coils inside the resistors will generate inductive fields. Another more practical way is to use a bunch of lower wattage resistors in parallel so the wattage is accumulated and the resistance kept low.

A trick that can be used to help in the dissipation of heat from the resistors is to submerge the resistor package in a fluid medium that will help dissipate the heat generated by the resistors making them more efficient. The trick with this is to use a medium that has a high flash point so you don’t accidentally start a fire. This is called a “wet dummy load.” It is recommended that transformer oil is used; this is what utility companies use for the same purpose in their large power transformers. Unfortunately this stuff is very expensive. The last time I checked it was $2,300 for a 55 gal drum, about $42 a gallon if you could find it in anything less than 5 gallons. Fortunately there is an alternate, mineral oil, which is pretty close.

So what’s in store next you may ask… A field strength meter is on the list for next week. With any luck I will be able to get out and do some shopping for that project in the next day or two.

That’s all for now, and 73
~FlyBoyJon / KK6GXG