Saturday, March 27, 2010


One of the frustrating parts of repairing older appliances is finding the right wire, especially power cord. Old ones very rarely survive in safe shape; most new ones look plain wrong.

For power cords, Sundial Wire has the answer. You've seen their work and haven't noticed it, in films and TV shows. They have very old-fashioned twisted-pair power cord...that just happens to be hiding modern insulation under the cloth.

Wiring up a classic radio or a telephone? Building retrotech from scratch? Check out the "Wire" listings under "Components" at Radio Daze; they have solid and stranded cloth-covered hookup wire in several sizes and many colors, including "pushback" solid, plus multiconductor cable and tinsel cord for telephone handsets, headphones and old-fashioned speakers. They have their own line of parallel-wire cloth-covered power cord and matching plugs, too.

Antique Electronics Supply has cloth-covered magnet wire in #24 and #26 size, plus Litz wire and cloth-covered hookup wire assortments, some power cord, cloth-type "spaghetti" insulating sleeving and #12 square tinned busbar.

Not Esoteric enough? Try the all-cotton-insulated wire at Jupiter Condenser Co. --And if you just have to have waxed-paper condensers, why, Jupiter's your only source of new ones, as far as I know. (The latter are not inexpensive but feature manufacturing techniques far superior to the old type; they've a line of modern Mylar fixed condensers as well). I have not done business with this company -- but they look interesting.

(Also stumbled over general-line/audiophile supplier Parts Connection, worth adding to your do-they-have-it? resources).

Wednesday, March 24, 2010


Sometimes, if you're looking in the right place, there are wondrous things to be found; some are very large, like the 1920s-designed city park in a quarry in Huntington, Indiana. Others are much smaller. My eagle-eyed friend Og found this and thought of me:It's the smallest "professional" sized Yankee screwdriver, the smaller ones generally being sold as "handyman" versions and marketed more to homeowners and casual users. It's in very nice shape, with the original box and bit envelope, though no bits. --I make a habit of picking up Yankee bits when I find them (and the hex-bit adapters), so this is no hardship. This one does not have a return spring; it is intended for work where control matters more than speed. A splendid gift indeed, and one that I'll use.


My favorite pair of glasses -- and the only ones with a current prescription -- broke awhile ago and I have been tacking them back together with Tix, a low-melting hard solder. Alas, the break was in a high-stress point, where the temple begins to curve around one's ear, and it wasn't holding.

There's a fix for that:It helps to have the toys to do the job but the real key is that stick of what looks like brass rod at the center of the image. It's hollow tubing from world-famous Hedlund's Hardware (Motto: "We have it. Somewhere." It's true, too) A little flux, a little Tix heated by the big iron and taa-daa:It's not beautiful but it doesn't show that much, either. And I'll be seeing the optometrist next week.

Saturday, March 20, 2010


In the 1930s, engineers at the Radio Corporation of America[1] introduced what they called "six-wire transmission line," a neat dodge that used U-shaped supports and a handful of insulators to turn ordinary wire into a good approximation of high-power coaxial cable (scroll down for drawings and photos) without all the trouble and expense of using large-diameter copper tubing: in cross-section, four wires apart occupied the corners of a square about twelve inches on a side while two more, very close together, were set in the center. The outer wires were all grounded (just like the outer shield of coax) and the center two, connected together, made up the center conductor. (Here's an example of genuine American six-wire line at WGY).

It got a little attention; the technology of the day used what's known as a "balanced two-wire line" between transmitter and antenna, both wires "live" and rather sensitive to weather and temperature, or even dodgier methods. But about then, a little war broke out and the engineers suddenly had different priorities.

The WW II development of fancy plastics, smaller concentric line and the boom economy of the 1950s left that Depression-era trick in the dust -- real coax made out of big copper tubing was just the ticket for the 250W to 5kW stations that made up the bulk of broadcasting in the U.S. and they could afford it.

...Other places don't do things the same way; in the rest of the world, fewer stations and higher power were more usually the case and in cases where one country sought to, ahem, get to know the neighbors better, very high power was the norm. Nobody makes coax for that and even if they did, most outfits -- many governments! -- couldn't afford it. But some wire, insulators and few custom castings? That's well within the budget and it leads to images like these.

The young gentlemen in the lower photograph are standing in (or nearly in) a ring that supports the outer wires of a scaled-up version of RCA's penny-pinching 1930s six-wire line. Call it five and a half feet in diameter, at least. Once completed, it carried a 1.2 million Watt signal from the transmitter to the antenna. Not bad for something an RCA guy dreamed up to avoid the cost and trouble of turning two sizes of water pipe[2] into coax, hey?

This is why it pays to remember old tricks.
1. At the time, not the "RCA Corporation," a name-change that was the knee of a long curve down for the former technology giant.

2. Honest. Early on, the commonest size of "rigid line" with copper-pipe inner and outer had a non-standard impedance (determined by the ratio of the diameters of the inner and outer conductors, times a fudge factor) because that's what you got with the off-the shelf pipe sizes. To this day, the outer conductors connect using standard large size high-pressure water-pipe flanges. But the inner conductor's now a size that, oh, gosh, a size that works out to a more slide-rule friendly number.

Thursday, March 18, 2010


A long time ago, back when I was shopping (the used market) for my Gerstner machinist's toolbox, I stumbled across an interesting no-name one that had a few...problems. Like somebody had carved big squarish openings in one of the drawers, and the outer case -- metal -- was in terrible shape, covered with flaking paint in a livid shade of green.

But it had this: I couldn't resist it. After all -- Hammarlund!

As you can see, the paint was fixable. The openings in the drawer front took a little more finagling:The small holes, I just drilled out to a consistent diameter (1/8") and filled with dowels. To fix the big ones, the drawer fronts were oak and I found some similar red oak, cut it oversize and did a lot of scraping and sanding. ...A whole lot of scraping and sanding. To hold the patches in place, I drilled from the top and bottom of the drawer front and glued in more 1/8" doweling.
At some time in the past, black ink or paint has spilled down drawer fronts, too; the only fix for that was sanding and refinishing, though I didn't want it piano-glossy like a new one. What's on it is mostly dark boiled linseed oil and multiple coats of wax. You can still see where the stain was but it's not too bad.

Trivia: The edge detail at the top of the drawers is a bead -- that's the rounded bit -- and a quirk, which is the little square-bottomed groove between the bead and the rest of the drawer front. This example's only a little quirky. Traditionally made with a custom plane, a scratch stock or (cheater!) router bit of the proper profile. The look can be faked with nothing more than a large flathead woodscrew, a bit of scrap wood and some sanding, but that's a story for another time.

Sunday, March 14, 2010


At long last, I have cleared my workbench! Taa-daa:Some interesting stuff on it, too. Across the top, my fancy extending light on a custom (see below) support hides a pair of hand drills, while the far end is occupied by a bench supply (450 VDC/100 mA plus lower B+ and heater supplies) and breadboarded tube utility amplifier ('76 triode driving '42s in push-pull!), both based on Modern Radio Labs plans. Lookie:Power Supply -- that's a real type '80! The shiny front panel is what happens if you have a buffing wheel and a lot of time; it's aluminum, which can be...interesting to buff: you have to do it all in one go, especially the final stages.Amplifier, with salvaged knobs (from an old Thordarson product) found all alone at a hamfest or surplus dealer. The finish on the plywood cabinet is brown shoe polish(!!) followed up with a little wax.

Next shelf has a commercial bench supply for tubes -- regulated 0-400 VDC (with current limiting!), ditto 0-100 negative for bias, and heater voltage. Simpson 260 next to it, the Meter You Should Own -- the Triplett 630 has its adherents, too -- one or the other, if you fiddle much with electronics, you'll want a real VOM and they're the definitive ones this side of the water. Both show up used at reasonable prices. Next to the Simpson, an RF signal generator, a hamfest find a couple of years old.

Various toys on the bench top -- an anvil, a Hakko high/low soldering iron at the far left, small hand drill, some drivers, a 4" square, an awl and my nice, big American Beauty 100W iron, plus a recently-modified small-tools holder.

Recently-modified? Glad you asked!
Here's the mod in progress; I was cheating by planing off the pencil marks, using a beat-up miter box as a vise-replacement (you clamp it to the bench and clamp the workpiece to the miter box). The wooden "Gent's Plane" was bought on sale, I think from Lee Valley, and is outstandingly good. (They don't seem to have that brand right now). It's true what they say about wooden planes. I cheated on drilling the holes vertically, too. I'm very fond of this tiny Plexiglas square for that purpose. But you're wondering what the thing does? Why, this: It's the driver-holder across the back, holding a couple of awls, a ratcheting multi-driver and two sizes of tweakers -- yes, that's the genuine tech-identifying Green Tweaker at the right.

The bracket for the accordion light? Built of scraps, old wood found here and there, but it's got wedged tenons at each end and all manner of done-by-hand chamfering. Did it several years ago, just to see if I could. I can.
It's not a thing of exceeding great beauty but it works. You can just see a bit of the chunky triangular block that's supporting it off the left side of the shelves.

Still to come: some diagonal bracing for the legs and perhaps installing my smaller carpenter's vise. (The bigger one, I'm saving for a sturdy woodwork-specific bench, probably out in the garage). And perhaps a project or two!
* Need tube data? Frank's the guy! Duncan's TDSL is nice, too.