Saturday, April 28, 2012


Receive a radio station with loudspeaker volume using nothing but a shovel? Yes, you can do that, but you have to be a little close to the source:

Scroll this video to the 3:30 mark and you'll learn the trick.

I shouldn't have to say it but I will: DO NOT TRY THIS AT HOME. Or at your local station. Really. They won't like it -- and neither will you, if the base impedance is high enough. Higher the Z, the higher the E and the higher the E, the farther the spark will jump. The fellow in the video has a nice, low-impedance point to use and a transmitter so big it doesn't care -- and it's still no fun for the shovel. (Do it to your little "coffeepot" AM and you can end up in the Feddie pen as a bonus prize; it's worse if you're crispy, too but they tell me it's no fun either way.)

Sunday, April 15, 2012


Built from an article he wrote for Radio (not QST!) as a young adult. I'll scan it in later.

Here's the front panel, bandset condenser at the upper left on the side, bandspread tuning via the National type B dial, regeneration at lower left and on-off at lower right:I had to build the chassis. It's just galvanized sheet metal -- aluminum might look nicer. Top view with the lid off -- band selection by plug-in coils! I didn't have any simple-type grid-cap clips but the little brass coil spring works okay:From below, you can see my efforts to "fine tune" the regeneration control with paralleled resistors. The original used a carbon-compression rheostat, an early multi-turn variable resistance, but I had to come up with a coarse setting: Multiwire cable out the back to the batteries -- 3V "A" and a 45V, tapped at 22.5V "B." The detector is a type '32 screen-grid tube with two stages of audio from the '19 dual-triode in the back compartment.

LATER: Here are the scans, of the photocopies I worked from back when I built it. I don't seem to have the first page and there's about a decade (110 issues) of RADIO to go through, so gimme a few. I used a different bandset condenser, detector plate audio-coupling choke and RFC -- his looks to be a Hammarlund.

Saturday, April 14, 2012


Actually, it's an exhibition, not a contest of speed. My three Vibroplex No. 4 or Blue Racer bugs of varying vintage:
L. to R, pre WW II, with a U-damper and "cloverleaf" frame; 1946, with scaled-down "Original" style upperworks; a 2001 "Millennium Bug" with full-scale mechanicals on a small base.

From the front, the frame differences are clear:
The damper variations show in the rear view:The oldest one had obviously been dropped and was green and nasty with corrosion when purchased. I replaced the thumbpiece and straightened the frame gently, enough so it would function. The reed (flat spring) had been deeply filed by a prior owner, an old trick to slow 'em down:
The very oldest ones had smooth blue-enamelled bases, probably with the gold-pinstriping treatment; my oldest probably dates from 1921 through '41 but without the nameplate (long gone), I don't think it can be narrowed down any more than that.

They all work pretty well. The 2001 bug has a "bug tamer" extension on the pendulum to slow it down. I'd like to add a "Vari-Speed" to the '46 De Luxe (sold here, scroll down for a video link of the gadget in action), and give that a try. The oldest one, with the filed reed and massive pendulum weight, is already just about right.

Monday, April 2, 2012

1946 De Luxe Vibroplex Blue Racer

In 1946, the year's production count still included the famous "Lightning Bug" derived J-36 military speed key built by Vibroplex. (Other firms, including Lionel, made J-36s, too.) All told, the company made over 4200 bugs that year, but only a fraction of that number were Blue Racers -- and only a fraction of those were all-chrome "De Luxe" models like my recent purchase.

In fact, from 1943 to '45, you couldn't even get a De Luxe with a chromed base: as a war measure, Vibroplex used battleship gray paint instead. It wasn't only Technicolor red that went to war.

By '46, chrome was back:And how! This is an early version of the De Luxe, with a conventional-looking upper pivot screw and jam nut, but that's a jeweled bearing and there another one for the lower pivot. The cord and wedge, properly tied off at the binding posts, is a nice touch and marks this key as likely to have been originally owned by a professional telegrapher -- the wedge allows the key the "plug in" to the employer-provided straight key (screwed down to the operating table) without making any modifications or disconnecting any wires. (Landline telegraphy is a series system: unhook any part of it and the whole line is out of service; so they tended to frown on it.)
The owner took care to mark the carrying case......Which isn't the official Vibroplex version, but a cut-down cheese box from a well-known cheesemonger!*

Price? $150, a fair deal for a key of this age, condition and with the cord and wedge.
* At last, a chance to use the word in a non-pejorative sense!