Yesterday, we posted this quiz from the November 1956 issue of QST. You have a 99-conductor cable, unlabeled, and you need to mark the conductors. If you have only a buzzer and battery, how many round trips will you need to make?

That issue of QST promised that the answer would be published “next month,” but I couldn’t find it. The December issue talked about the October quiz, and there was nothing in the January issue. So much to the consternation of 1956 hams, the solution was never pHappy Valentine’s Day! | OneTubeRadio.comublished.

Fortunately, we now have this internet thingie, and it’s possible to find answers to questions like this. It turns out the puzzle was originally authored by Martin Gardner, the Scientific American puzzle columnist, and editor of Humpty Dumpty’s magazine. Only one round trip is necessary. Here’s the full solution:

DX4U can identify and label all 99 conductors with just 1 round trip (Side A → Side B → Side A) across the chasm.

Step 1: At Side A (Starting End)

1. Pick any single conductor and leave it isolated. Label it Wire 1.
2. Take the remaining 98 wires and twist them into 49 separate pairs:
   • Pair 1, Pair 2, Pair 3, …, Pair 49.

(At this stage, Side A has one isolated reference wire and 49 independent closed loops.)

Step 2: First Trip (Cross over to Side B)

DX4U crosses the chasm with the battery and buzzer tester:

1. Find Wire 1: Test continuity across combinations of wires. Exactly 49 pairs will buzz, leaving one single conductor that shows no continuity to any other wire. That isolated conductor is Wire 1. Label it 1.
2. Map the 49 pairs: The buzzer quickly identifies which wires belong together in the 49 pairs. Label these pairs arbitrarily:
   • (A₁, B₁), (A₂, B₂), …, (A₄₉, B₄₉).
3. Daisy-chain the wires in series: Connect the pairs into one long chain:
   • Connect Wire 1 to A₁.
   • Connect B₁ to A₂.
   • Connect B₂ to A₃.
   • … continue chaining until B₄₈ connects to A₄₉.
   • Leave B₄₉ unconnected.
4. Label Side B permanently in order:
   • Wire 1 → 1
   • A₁ → 2, B₁ → 3
   • A₂ → 4, B₂ → 5
   • …
   • A₄₉ → 98, B₄₉ → 99

Side B is now completely identified and labeled!

Step 3: Second Trip (Return to Side A — Completing 1 Round Trip)

DX4U returns to Side A and untwists all 49 pairs made in Step 1.

1. Trace from Wire 1: Using the battery and buzzer, test from known Wire 1 against all loose ends. The one wire that buzzes is connected to Wire 1 across the chasm, so it must be Wire 2.
2. Decode Wire 2’s partner: Because Wire 2 was originally twisted with a specific partner wire in Step 1, its old partner is instantly known to be Wire 3. Label it 3.
3. Trace the rest of the chain:
   • Test from Wire 3 to find the wire that buzzes → that is Wire 4.
   • Its original Step 1 partner is Wire 5.
   • Repeat down the line until all 99 wires are labeled.

Every single conductor is now uniquely identified at both ends after exactly one round trip.

Seventy years ago this month, the November 1956 issue of QST carried this quiz. You have a 99-conductor cable, unlabeled, and you need to mark the conductors. If you have only a buzzer and battery, how many round trips will you need to make? We’ll post the answer tomorrow.

Sixty years ago this month, the October 1966 issue of Popular Mechanics showed how to put together this pocket guitar amplifier. Of course, the entire amp didn’t fit in your pocket–what you built was a miniature transmitter, and the other half was any AM radio. If the radio was battery powered, then the entire setup could be used off grid. Or, if your venue had an AM radio, you could simply use that.

This ad for WYSR, Syracuse, NY, appeared in Broadcasting 85 years ago today, October 27, 1941. It announced that the station was now 5000 watts on 570 kHz.  It was billed as the perfect combination, because a signal on that frequency has a much greater reach than a station on a higher frequency.  In this case, the ad notes that a station on 1400 kHz would require 340,000 watts to have the same coverage area.

Here in the Midwest, WNAX in Yankton, SD, has the same frequency and power, and it blankets four states with its signal.

Eighty years ago this month, the October 1946 issue of Radio Service Dealer carried this ad from GE about the facts of life, namely, the importance of good replacement dial lamps for your radio.

Of course, it wasn’t just a cosmetic issue.  In an All American Five receiver, the dial lamp played an important role, and you would want to replace it as soon as possible if it ever burnt out.   It was wired generally directly across a tapped heater section of the rectifier tube. In this spot, the bulb acted as a current-cushioning ballast that absorbed the dangerous power surges that occur when cold vacuum tubes first switch on.  Running a radio with a dead dial light overloaded that rectifier filament, quickly destroying the expensive tube and disabling the entire set.

Eighty-five years ago, this gentleman (Bill) and his wife Mary were experiencing a dilemma about their radio.  It wasn’t working, and Mary suggested that because Bill was always fooling with radio, that perhaps he could fix it.  Bill lacked confidence, but undertook the repair anyway, knowing that he would make a fool of himself.

Fortunately, Bill’s friend Joe just happened to stop by and gave some pointers.  Joe had started the National Radio Institute home study course, and was able to diagnose the problem for the free introductory lesson.

Bill went on to a successful career in radio.  The ad appeared in the October 1946 issue of Radio Craft.

Seventy years ago, Popular Electronics had been running a series of simple projects designed to show off what transistors could do. And the October 1956 issue featured this simple two-transistor regenerative receiver. The magazine doesn’t mention the frequency range, but from the looks of the coil, it appears to be for the broadcast band.

The circuit used a 2N35 NPN transistor for the regenerative detector, with a CK722 audio amplifier.

Seventy-five years ago, the BBC realized that it needed to start broadcasting on VHF. The reason was simple: The mediumwave band in Europe was too crowded. But unlike America, which had been using FM on the old 42-49 MHz band, and was about to move to 88-108, Britain hadn’t decided on whether to use AM or FM modulation on the VHF band. In order to decide, they ran a test in the London area. From the same antenna, two signals would be broadcast, both carrying the same program. The transmitters are shown above, from the October 1951 issue of Radio Electronics.

Both transmitters used approximately equal power, with the AM signal going out over 93.8 MHz, with FM on 91.4.

Fifty years ago this month, the October 1976 issue of Field and Stream carried an ad for this interesting radio receiver, which undoubtedly appealed to the avid outdoorsman.

The GE Model 7-2995 (or 7-2995A) was a portable AM-FM receiver powered by six D-cells, so the batteries were sure to last a long time.  But it was also a scanner covering the VHF high band (150-174 MHz) for tuning in on action such as fire, police, and marine bands.  It required no crystals, as the four channels could be preset.  Undoubtedly, it was a slightly painstaking process getting them tuned in initially, but once they were set, there were no crystals to buy.  If you didn’t need AM-FM, the scanner by itself was available as the model 7-2985.  The picture of that set reveals that the tuning is accomplished by individual adjustments concealed by a small door.  So no tools were needed to adjust the tuning, although a little patience was probably helpful.

I don’t think I’ve ever seen one of these in person, but examples are available on eBay.

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