March 26, 2010


Prior to receiving my ham radio license in 1991, I was already an electronics experimenter.  I had built a lot of audio-frequency gear, such as guitar effects devices and preamps and mixers and such.  But I didn't really keep good notes on the stuff I made.  Shortly after I was licensed (originally as N0NZQ), I decided to begin a radio electronics experiments notebook.  In it I keep schematics of circuits I've built, results of experiments I've tried, calculations of component values for VFOs, and stuff like that.  I also periodically have written down my amateur radio goals for the year.

I've drifted in and out of the hobby over the years (mostly because work or other interests have supplanted radio at times), so I'm still using the same notebook I started with (although it is nearly full now).  (For what it's worth, the notebook I chose was one of those composition notebooks with the black speckled cover, like they sell at college bookstores, except mine was filled with graph paper, to make it easier to draw neat schematics and diagrams.)

Anyway--today I sat down and reviewed that notebook, which now covers about 18 years of messing around with radio electronics.  And I read with particular interest my recurring lists of goals, noting that some of the same goals keep coming up, time after time.  For example, it seems like I'm always hoping to get a better antenna system up, and another recurring theme is the goal to build small QRP rigs for every HF band.

One of the things I've learned over the years about setting goals (not just in ham radio, but in any area of life) is that it is a good idea to review them periodically, keep track of your progress, and if necessary, change or update them.  This spring I think I'm finally going to get that antenna project done--my new son-in-law is a strapping young man who is game for climbing a tall tree in my back yard, so I'm optimistic that I'll at least have some wire up soon, higher than I've ever had it before.  I also have noted that I have completed small QRP rigs for 40 and 20 meters--granted, they were kits and not purely homebrew designs, but I'll count them.  One goal was to try one of the digital modes--PSK31, and while I haven't transmitted in PSK31 yet, I've got some software and have been able to receive, so that goal seems attainable soon, too.

My goals in the past have often included acquiring or building various bits of test gear, and I've been fortunate in that regard, as well.  I now have a pretty nice (albeit basic) 30 MHz oscilloscope to replace an old 5MHz 'scope that I borrowed from my dad years ago.  I've managed to find a nice frequency counter at a hamfest, and a signal generator, too (although it only goes to about 2MHz).  I've recently built a crystal test oscillator that works from around 2MHz to around 25MHz, which has been quite useful, and I also built a small dual-range QRP wattmeter--it's not calibrated, but it has two ranges (50 mW and 4W), and it's enough to tell me if I'm stirring the ether at all.  One of my goals for this year to is figure out a way to calibrate the thing and replace the meter's scale with one that is more useful to me.

So here are some of my latest goals:
  1. I want to build something with tubes.  I have a bunch of old tubes and high-voltage parts (resistors and capacitors), plus some broken tube-type gear that I can cannibalize for parts.  Maybe I'll start with a simple one-tube regenerative receiver or something.
  2. I want to restore an old Atwater-Kent radio that a friend gave me a few years ago.
  3. I want to restore a couple of old tube testers that another friend gave me a long time ago.
  4. I want to build a CW rig for 6 meters.
  5. I want to try my hand at QRSS or WSPR.
  6. I want to experiment with frequency multiplier circuits.
  7. I want to build a variable DC power supply.
  8. I want to build a very small trail-friendly 40-meter CW transceiver to take on hikes and bike trips (with a portable antenna and transmatch).
  9. I have a large supply of 2N2222 transistors, so I'd like to try one of the 2N2-xx rig designs.
That's probably enough to keep me busy for the year, don't you think?

So (in case there is anyone reading this out there), what are YOUR goals for this year?

73 de aa0ms

March 25, 2010

Radio-related calculators

I was messing around in the shack today, breadboarding a signal generator circuit from Ashhar Farhan's (VU2ESE) Web site. He wound his coils on fast-food soda straws, I didn't have any straws lying around, but I did have a bunch of T50-2 powdered-iron toroids, so I decided to use a couple of them. I wasn't entirely sure about the inductance of VU2ESE's coils (he just gave the number of turns), but he did mention that he designed the signal generator circuit to run from 3 to 30 MHz, and given the size of the tuning capacitor, I did some rough calculations concerning what inductance would be required to resonate in that range.

Armed with that information, I went Googling in search of a toroid calculator, and found this calculator site, with exactly the sort of toroid calculator I needed. You just pick the type core you're using (iron powder or ferrite), pick the core size, enter the desired inductance, and the calculator gives you the number of turns to wind on it.

I thought it was pretty cool, anyway, and it saved me some time (and math).

73 de aa0ms

March 23, 2010

The LowSWR Podcast

When I first started listening to the Soldersmoke podcast, it didn't appear to me that there was a lot of other amateur radio stuff out there in the podcast world. That's been a few years ago now, and the other day I decided to check again and see what's available, and I stumbled upon the Low SWR Podcast, hosted by Rich (KD0BJT) and Brady (KD0BJS). I'm only a couple of episodes in so far, but I like this one, and I think the appeal is partly the presence of young KD0BJS--I'm not sure how old he is, but he sounds like a very bright young man, and it is very cool that he's gotten into the hobby with his dad, and that they are collaborating on the podcast.

I hope you'll check it out! You can subscribe in iTunes, or via the RSS feed on the Low SWR Web site.

(I've since loaded up a couple of other ham radio podcasts on my iPod, and once I've had a chance to listen to some of them, I'll post some information for you.)

73 de aa0ms

Caps are often the culprit...

I recently viewed an episode of the Electronics Engineering Video Blog by Dave Jones, from Australia, and was reminded that capacitors can be awful. (Go check out Dave's video blog sometime--great fun.) He did a two-part series on capacitors last fall that was entertaining and informative, and it reminded me of some of the troubleshooting and repair tasks I've faced in the past.

Seems like many of the times I've been successful in repairing broken electronic equipment it's been because I successfully identified an electrolytic capacitor that had ceased to work properly. Recently I decided to investigate the reason why one of the output channels of one of my audio mixing consoles wasn't working any more. I hooked up a signal generator to an input and began tracing the signal through to the output, and sure enough--at one point the signal looked fine going into an electrolytic cap, but it didn't show up at all on the other side. This was one channel of a stereo signal, and the signal appeared on both sides of a similar cap in the other channel, so that's what tipped me off. (It's not that I had any great understanding of the circuit function!)

Turns out that that cap was located fairly close to a voltage regulator chip that tends to run fairly warm, and I suspect that that heat contributed to the cap's failure. Electrolytics can be a weak link--they can dry out as they get old, they can be adversely affected by heat, and there are a lot of low-quality electrolytics out there.

If you're like me, you don't throw any piece of broken gear away--you salvage whatever parts you can strip from it. I would humbly suggest that you be sure to check the electrolytics you pull from old gear before you stick them in your junkbox--they could be evil!

73 de aa0ms

March 22, 2010

Lots of stuff added to my pages

If you haven't checked out the pages links at the top of the right sidebar, you might want to take a look--over the last few days I've been adding a lot of links to other people's blogs and sites, plus some reference-type pages and resources. Some of these I've found myself while net-surfing, others I've found on other people's links pages. I'm trying to keep the signal-to-noise ratio good, though, and only include the sites that seem to me to be the best (and which are actually up and running).

Also, the picture of my bench that I sent to Bill (N2CQR) for the Soldersmoke blog got a nice mention in his excellent blog--thanks, OM.

More to come.

73 de aa0ms

March 21, 2010

Keeping test leads organized and handy

A few years ago I bought a roll of test-lead wire and various styles of banana plugs and test clips to make my own test leads. The problem has always been with storage. For years they were all just stuffed in a drawer that, as you can imagine, became a mess--a rat's nest of wires and such. I don't have a lot of space around my bench for hanging test leads, but when I was reorganizing things the other day, I found a length of plastic angle stock (don't remember what I bought it for), and decided it would make a nice test lead rack.

I drilled a series of holes along one face of the stock, just big enough to put a banana plug in, then mounted the strip vertically next to my bench. Now the test leads I need are easily accessible and tangle-free!

73 de aa0ms

My experiment box

Seems like I'm always breadboarding a VFO or something around here, and I always end up with a rat's nest of clip leads and wires when I'm testing the thing, so I decided to make a little test box that I can use for such experiments. The case is plastic, but it is sprayed on the inside with conductive paint ("nickel-spray," I think they call it), and I've mounted a piece of unetched copper-clad fiberglass circuit board to the bottom. I've added a smaller strip of copper-clad board to that (to use as a power-supply buss, for example, and a small terminal strip. The front and rear panels of the case are also made from double-sided copper-clad board, and on one panel, I've mounted a couple of banana jacks for power and an RCA jack; on the other panel, I've mounted two BNC jacks.

I can build circuits right in the box, or I can build them on smaller scraps of copper-clad board and mount them in the box, with power and signal connections to the appropriate jacks. Although the lid is not shown in the photo, I can also attach the lid if shielding is necessary when testing.

Although I have a couple of small solderless breadboards, I really prefer soldering parts together, ugly-style, when I'm experimenting, and this little box makes it very easy to deal with power and other connections.

73 de aa0ms

Cool stuff from my dad

My father, ex-K8LZO, was the one who got me interested in ham radio and electronics many years ago, in the late 1950s and early 1960s. Although it was many years before I decided to go ahead and get my ticket, I never forgot the pleasure of sitting beside him in his shack, watching him put together Heathkit kits, or tinker with bits and pieces of homebrew gear he was working on. I was fascinated with the sounds of CW that came out of his homemade speaker cabinet, and after he worked a station, he would point out the QTH on a big U.S. map that hung on the wall above his bench.

Sadly, he's inactive now, but the other day he gave me several boxes of stuff he had left over from his radio days, and here are some of the treasures he gave me. The first photo below is a 15-meter mobile rig he built from scratch. It's about 10 inches wide, 7 inches high and 8 inches deep--hard to imagine mounting that under the dash of the family car, but I have dim memories of him using that rig on a family vacation--mostly I remember that the ground-plane antenna he built on top of the car kept blowing off (it was attached with a large white rubber suction cup, as I recall).

Here's a photo of the VFO--he shielded the main tuning capacitor with tin from a Kodak photo chemical can:

Here's a Heathkit SG-8 R.F. Signal Generator that he built--it still works to this day, and it's surprisingly stable, all things considered. Observant Heathkit owners will notice that the output connector (under the green power lamp lens) is not original--a few years ago I replaced the funky old-style mic jack (like the ones on the left side of the front panel) with a BNC jack. I apologize in advance to any purist who considers this an abomination and an affront to all things Heath.

There are many other interesting things that I'll post later on--a whole bunch of old germanium transistors, for example, and an RCA 902A CRT, with a 2-inch screen. There's also an old 813 power tube, given to him by the engineer who worked at the radio station across the street from our house in Cambridge, Ohio--he had hoped to build an amplifier with it some day, but never got around to it.

There were piles of carbon-composition resistors, mica capacitors, even some old paper caps that are probably not any good any more, but I'll probably keep them around for sentimental value.

The last photo for this post is (I think) the beginnings of a keyer that he was in the process of building. I'm not sure it ever worked, but he kept it for years in hopes of reviving the project at some point:

Can I ever relate to that...

More to come later.

73 de aa0ms

The AAØMS bench

Okay--to kick this blog off properly, here is a photo of the workbench in my shack. The bench and operating position share a table (I know some would recommend against that, but that's the way my space has to be organized for now). It is a constant struggle to keep it neat enough that there is space for me to work on projects or operate my radios. The photos may not suggest that I'm staying on top of this, but trust me--it's been a LOT worse.

The main rig (an Elecraft K2, #03106) is at the far right, with a Small Wonder Labs SW-40+ sitting on top of it. That's an Astron RS-12A power supply behind it and to the right. On the shelf above it is an MFJ-949D tuner. To the left of the main rig is a Sangean ATS-803a short-wave receiver. At the center left in the photo is an Ugly Weekender I built--my very first homebrew rig, built in 1991. (I'll share some more detailed photos of that rig in a future post.)

Above the SW receiver are some bits of test equipment--an oscilloscope at the top, and a frequency counter and function generator below that.

At last count, I have four different multimeters in the shack--a couple of DVMs and a couple of analog VOMs. I've also built a QRP dummy load, a QRP power meter and a crystal tester--I seem to have accumulated a lot of surplus crystals.

That's the bench--more to follow.

73 de aa0ms

March 19, 2010

Do we really need another blog?

No, probably not--but in recent months my interest in amateur radio has been rekindled, and since I have benefited so greatly from the blogs of other amateur radio homebrew hobbyists in these past few months, I decided that perhaps others might benefit from my experiences, as well.

When I was first licensed in 1991 (as NØNZQ), blogging didn't really exist as it does today. Because of the normal requirements of family life and work over the last couple of decades, I've been in and out of the hobby a few times, sometimes allowing years to go by without ever plugging in my soldering iron or turning on a transceiver. When I finally started to get back into radio over the past winter (after a five- or six-year hiatus), I was very pleased to find a wide variety of amateur radio blogs and Web sites that didn't exist a few years ago.

I've done a fair amount of blogging myself, in other areas of interest and profession, so creating a chronicle of my radio and homebrew activities seems like a reasonable thing to do. (I will also benefit from having a digital record of my projects and experiments, so even if no one else ever reads this thing, it should be useful to me.)

So, on the off-chance that someone besides me reads this, thanks for stopping by. I can't promise that I'll be posting every day or even every week, but there will be more to come.

73 de aa0ms