Gear and Gadget Notes – 9/10/11

Here are some gear and gadget notes:

  1. Ed, WA3WSJ, has opened up the Hot Water Corner, a website devoted to Heathkit HW-xxx radios.  He says, “If you have any pictures of your Heathkit HW-xxx radios, please send then to me with a story about the rig(s). I’m sure others would like to read your story.” I need to dig out my HW-101 and take some pics of it.
  2. On the AMRAD mailing list, Terry, WB4JFI recommends the SDR Cube.  He says,

    I wanted to say how impressed that I am with George Heron’s (and OH2NLT) SDR Cube kit. I have an SDR Cube Development setup sent by George, as I am considering how to interface it to the Charleston SDR & Digilent FPGA boards. I have since ordered and received a complete SDR Cube kit, less the Softrock 6.3, which I already have. I anticipate cutting some traces, and soldering additional wires directly onto the dsPIC chip for the Charleston interfacing, so I needed my own boardset.

    The kit has excellent instructions, see the sdr-cube.com website. Each board comes prepackaged with its own parts, with SMT resistors and capacitors taped to a paper sheet, and ICs in a small anti-static bag. I have put together almost two boards so far, and everything went together very nicely. Almost Heathkit quality instructions and construction techniques.

    I normally don’t like to push a vendor, but this kit is very well done.

  3. Looking for a club construction project? Consider the Sure PS-LP11111 5~16 VDC linear DC voltage power supply kit. I think this fits the bill perfectly for a club construction project. It’s inexpensive, relatively simple to build, and when it’s complete, the builder has something useful. As one of our club members pointed out, this isn’t actually a complete power supply—it’s missing a transformer and enclosure—but it costs less than $9 in quantity. Suitable wallwart transformers can be purchased for about $5 mail order, probably less if you snoop around the next hamfest.

Operating Notes – 9/10/11

Some operating notes covering the past couple of weeks:

  1. The bands have been in fine fettle most evenings lately. I’ve been getting great reports and stations have been booming in here. It’s made operating a lot of fun.
  2. Despite that, conditions on 20m seemed kind of poor today while operating down at the museum. I made a couple of contacts in the Arkansas QSO Party, then turned the beam NW and worked a station in Luxembourg that was operating some European DX contest. Luxembourg is a new country for us.
  3. I don’t know if our 40m dipole has deteriorated, or the conditions have been marginal, or if it’s the difference in antenna performance between the beam and the dipole, but operating on 40m is now just a real pain. We’re scheduled to move the dipoles on Thursday, and I’m hoping that rebuilding the dipole and moving it to the other side of the roof will help.

Two Radios for You to Build

On the AMRAD mailing list, Andre, N4ICK, posted a link to the YouTube video, “12AU7 regenerative radio on a tin bake plate” (see photo at right) It’s a very cool regenerative radio made with a single 12AU7 vacuum tube. The only problem is that there are no links to the schematic for the radio.

So, I Googled a bit, and came up with this circuit. The cool thing about this circuit is that it uses a 12V power supply, not the high voltage power supply normally required for a tube circuit.

Over the weekend, I went to a big rummage sale sponsored by the local Kiwanis club. They had quite a few aluminum baking pans there for very little money. I should have picked up a couple of them. :)

Simliar Radios
VK3YE has also posted a YouTube video
of his experiments with a similar circuit. Unfortunately, he also doesn’t include a link to a schematic.

Another related YouTube video is for a one-transistor radio. This is actually a very well-done video. It shows you step-by-step how to build the radio. This is something that we may actually be able to do down at the museum with some kids.

At the very least, watching the videos is amusing. At best, maybe they’ll inspire you to do a little experimenting.

Build a TX for the 1929 QSO Party

This from VE7SL via the qrp-l mailing list:

If any of you were thinking about putting something together for the Antique Wireless Association’s 1929-style QSO party, there is still time to throw together a little Hartley or TNT!

The 1929 QSO party runs Dec 05/06 and Dec 10/11 (2300z-2300z). This is the contest where entrants are required to use a tube and tx circuit design that was only available in 1929 or earlier (210, 245, 27….there’s a bunch of them, mostly triodes). No xtals are allowed …..self-excited oscillators only! Your transmitter doesn’t have to look pretty either! Most of the activity is on 80m (3550-3580) but there are always a handfull of brave soles venturing way up to 40m (7040-7060) as well.

There has been a significant rule change this year that allows the ’29 member stations to work non-’29ers for points (previously these QSO’s could not be scored) so even if you don’t put a transmitter together, please join in the fun and listen to the chirps and buzzes of what the bands once sounded like….and then call them!

For inspiration, I have posted a gallery of eligible transmitters. The AWA has a ‘quick-build’ plan on their website, and a page on replica vintage transmitters.

Hope to hear you in the contest.

73 / Steve

An Interesting Find

Recently, someone donated an entire TS-820 station to our Ham Radio at the Hands-On Museum project. The equipment included a fully decked-out TS-820, plus a lot of other stuff from that era (the late 1970s), including a Heathkit code practice oscillator, a Handbook, and other assorted books and materials.

I’d looked through this stuff before, but somehow I’d overlooked the Heathkit Amateur Radio Log. Here are a couple of scans I made:


heathkitlogp1
heathkitlogp2
heathkitlogp3

Kinda cool, isn’t it? I’d never seen one of these before.

Hams Aren’t the Only Nuts Who Restore Old Electronics


IEEE Spectrum is running a short article on a group of “vintage” engineers who are restoring a vintage IBM 1401 computer. The computer had been in storage, but there was extensive water damage, damage that took 10,000 man-hours to repair! Think about that next time you get your hands on an old Hallicrafters.

Make sure to check out the slide show at the end of the article.

WD8DAS Searches for Heathkit

While his family went to the beach, WD8DAS visited the sites of the old and new Heathkit plants in St. Joseph, Michigan.

A Tale of Two Tubes

A couple of weeks ago, I worked N4QR on 40m CW. I could tell by the tone of his signal that he was operating a homebrew transmitter. There wasn’t any 60 Hz on his signal, and it didn’t chirp exactly, but I could tell it wasn’t the pure tone you get out of today’s radios.

I asked him about his rig, and he told me that it was a one-tube transmitter made with a 6L6. I forgot to ask him where he got the schematic, but a quick Internet search turned up the following:

  • The May 2005 issue of the K9YA Telegraph has an article written by N4QR titled, “The Wonderful One-Tuber,” that contains the schematic for the transmitter. The K9YA folks don’t make issues of The Telegraph available on their website, but I was able to get a copy of the issue by e-mailing them.
  • A 6L6 Classic (shown below)
  • WB2MIC 6L6 Transmitter Project


This one-tube transmitter is made with a 6L6 pentode.

The 6L6 is a pentode that, according to Wikipedia, was introduced by the Radio Corporation of America (RCA) in July 1936. Apparently, it was used quite a bit in public address systems.

After the tube became successful, tube manufacturers introduced a number of variations, including the venerable 807. The original 6L6 was capable of delivering 19 W; the latest variation, the 6L6GC is rated for 30 W. The 6L6GC is still used in guitar amps, and is still manufactured in Russia, China, and by Groove Tubes in the U.S. They sell a number of different 6L6 variants; the cheapest is $16, the most expensive $180!!

Tube #2
One of the reasons I was interested in the 6L6 is because about a year ago I came across a schematic for a transmitter using 6A6 dual triode. I had just come into possession of a couple hundred tubes, and while I didn’t have a 6A6 (at least I haven’t found one yet), I do have a couple of 6J6 dual triodes. They’re not quite as high power as the 6A6, but I’m still thinking about building a little transmitter with one.

As you might expect, there’s a bunch of information on the Internet about this tube:

One interesting fact about the 6J6 is that IBM used it in the 604 computer. Unfortunately, they found it to be not as reliable as they wanted it to be, but at first none of the tube manufacturers were interested in making a more robust version. This led IBM to set up a tube-making laboratory where they could experiment with designs. They developed a more reliable version of the 6J6 and finally convinced RCA to manufacture the tube. According to the author of the history of the 604, part of the concern is that IBM would decide to get into the tube business.

So, the next time you hear a signal that doesn’t sound so perfect, remember that there just might be a story behind it. Ask the op about his transmitter, and listen to what he or she has to say.

The Wesco BN-1

The latest buzz on the Glowbugs mailing list is about the sale of a Weskit BN-1. This rig, apparently sold by Western Radio of Kearney, NE is a one- or two-tube “Novice transmitter/receiver.” It originally sold in kit form for $14.95, assembled and test $19.95.

bn1

Sheldon, KC0CW, actually has a very nice writeup, which includes a schematic, about this radio. In part, he writes:

The Weskit transmitter-receiver was made by Western Radio (a.k.a. Western Electronics) of Kearney, Nebraska, around the 1956/1957 time period. It is an extremely simple rig, using only a single 7 pin miniature type 3A5 tube. This dual triode tube, which typically serves as a push-pull audio output tube in battery powered portable receivers, performs the transmit function with one triode, and the receive functions with the other. The front panel as shown above, is made of thin sheet metal, with a rather attractive gray paint job with red screen printed markings. The sides, top, and bottom of the box are made of a plastic impregnated cardboard, while the back of the unit remains open.

The transmitter is a modified Pierce crystal controlled oscillator on the 80 or 40 meter amateur bands. The L-C tuned plate tank circuit is link coupled to the antenna, and a type 1843 incandescent lamp in the antenna circuit is used as a tuning indicator. After tuning, the lamp is to be replaced with a type 41 lamp to reduce resistive losses. Power input can be as much as 5 watts with 180 volt supply, however the instructions suggest plate supply voltages as low as 45 volts, with “nominal” operation at 90 volts, with about 1 to 1.5 watts input. Snap on clips are provided for connection to dry cell batteries for high voltage, and a single D-cell battery holder is provided for the filament supply. Switching from transmit to receive applies filament power to only the half of the tube which is in operation.

The receiver is a regenerative type. Regeneration is controlled by a potentiometer across the feedback winding of the tuning coil. Frequency coverage is claimed to be 3400 kc to 8000 kc in the manual, however dial calibration does not go below 3500 kc. Audio output is intended to be fed to high impedance headphones. An optional stage of audio amplification using a type 3V4 tube can be added for operation of a small speaker. A pre-punched hole in the chassis can be utilized for the purpose of mounting the additional tube.

As you can imagine, comments were mixed.

One guy commented, “What a cutsy-kewl rig; and it’s DC powered to boot!”

Another replied, “I remember seeing an ad for the bn-1 when I was a novice and taking offense at the word ‘novice’ emblazoned on the face of the poorest excuse for a lunchbox with knobs I had ever envisioned. I still think that abomination was designed and marketed as a joke. I just cannot imagine any sane ham buying, building, or even wanting something that crude. The folk that brought that thing to market were confusing the words amateur and fool.”

A third said, “The thing with such gizmos, like the one-transistor radios and such that were advertised in the same era magazines, is not to expect miracles for your money. That the ad was the size of a postage stamp should be a clue to any reasonable reader that you were not dealing with the National, Hammarlund, or Hallicrafter class. The thing does work, whether you like it or not. What’s not to work?

“A 1-watt transmitter and a 1 or 2 tube receiver. Granted, the
tuning rate is atrocious, but it was intended to just tune to the frequency of the crystal.

“I prefer to consider such gizmotron products as kind of a friendly joke. The buyer understands, somewhere in his head, not to expect miracles, but you can still hope for them. The company provides a not-expensive learning experience (and I don’t mean learning about being ripped off!! ) and makes a little money as well.”

It does kind of amaze me that someone would actually buy one of these things, but as the last guy says, you could get them to work, and if they weren’t stellar performers, they were cheap, so it was an inexpensive education.

Three Random Links

Three random links from my pile of “links to post one of these days.”

  • HP Archive. This site is run by Glenn Robb, an Electrical Engineer and HP aficionado. It’s goal is to help others collect, preserve and enjoy vintage HP equipment and literature. By making hard-to-find documentation easily available to all, it is hoped that others will begin collecting HP, and help preserve the shrinking supply of vintage materials. This site will serve to organize a community of collectors, experts and gather volunteers to work together towards a common goal of preservation.
  • Simple CPO. Build this simple code practice oscillator (CPO) in an Altoids tin. The straight key is mounted on the lid.
  • Surface-Mount Kits. Nightfire Electronics offers a number of different kits and prototyping boards for surface mount circuits.