Fifty years ago this month, November 1964, Electronics Illustrated reviewed Allied Radio’s Knight-Kit Star Roamer Receiver.  I never had one, but this basic receiver was ubiquitous in the 1960’s and 1970’s, and many SWL’s got their start with the four-tube receiver.

According to the magazine, the kit sold for $39.95 and took about 20 hours to build.  The receiver’s low tube count was courtesy of a selenium rectifier and solid-state diode detector.  The radio did receive CW, but without a BFO.  The final IF stage was designed so that it could break into oscillation, making the receiver quasi-regenerative.  Interestingly, the radio included a key jack, since the oscillating stage could be used as a code practice oscillator for an aspiring novice to work on learning the code.

The receiver tuned 200 kHz to 30 MHz, but as the review points out, the longwave band was almost useless, and the overall performance left a lot to be desired.  But in an environment filled with strong shortwave signals, even a simple receiver like this one would give hours of interesting listening to the new SWL.

Good specimens seem to go for about $50 on eBay.  But if you’re in the market, there’s really no sense in getting a working one.  The simple receiver is easy to work on, and the full assembly manual is readily available.  This receiver would be a good candidate to “re-kit”: Take it apart, and keep the mechanical parts, IF transformers, and variable capacitors.  Then,  replace the resistors and capacitors with modern replacements.  The selenium rectifier is probably best replaced with a more modern silicon rectifier.  The old tubes are almost certainly good, and even if they are not, they are all easily obtainable as “new old stock.”  Finally, put it back together according to the manual (and the cautions contained in the EI review).

I’m not sure exactly why one would want a combination book light and radio, but if you wanted one 75 years ago, Popular Science for November 1939 showed you how to build it.  It was billed as being extremely useful for reading in bed, assuming of course, that you have a handy aerial and ground connection nearby.

The radio itself is a basic one-tube regenerative receiver.  It uses two trimmer condensers, one of which handles tuning and the other regeneration.  The particular tube used in this circuit appears to be unobtanium.  It looks like a standard miniature tube, but it’s actually a Hytron “Bantam Junior,” with a proprietary bakelite base.  The receiver drove a pair of headphones, presumably for quiet bedtime listening while reading.

The radio column for the Milwaukee Journal 75 years ago today, October 30, 1939, touches on the phenomenon of “border blasters” in Mexico and how they affected U.S. radio listening. Milwaukee was essentially the same radio market as Chicago. Even though Milwaukee had its own stations, listeners there ordinarily listened to the Chicago stations, including WCFL, then on 970 kilocycles. In 1939, WCFL carried the NBC “Blue” network, and would have been the main outlet in Milwaukee for listening to that network.

During the daytime, WCFL would have provided good coverage to the Milwaukee area, but the situation was different at night. The radio columnist, Edgar A. Thompson, pointed out that listeners who wanted to hear the NBC symphony, conducted by Arturo Toscanini, especially in the northern suburbs of Milwaukee, would experience difficulty to to the 100,000 watt signal of Mexican station XEAW in Reynosa on 960 kilocycles.

The solution was to tune instead to KDKA Pittsburg on 980 kilocycles, where the columnist reported that he heard the entire concert on a five tube “midget” table radio with good reception.

XEAW was one of the “border blaster” stations in Mexico, broadcasting with powerful transmitters that blanketed North America from just across the Mexican border.  XEAW was owned for most of the 1930’s by Dr. John R. Brinkley, a Kansas physician (with a degree from a diploma mill known as the Eclectic Medical University in Kansas City).  Brinkley’s most famous cure involved an extract from goat testicles that would allegedly cure various maladies.  By 1939, Brinkley had sold the station to Carr Collins, another practitioner of alternative medicine, whose “Crazy Crystals” from Mineral Wells, Texas, were reported to have various curative properties.  It was probably Collins who was causing the interference to WCFL reported in this news item.

Brinkley owned at one time or another various of the “Border Blaster” stations in Northern Mexico, and he was quite well known throughout the United States.  My dad recounted hearing Dr. Brinkley, and his broadcasts were apparently a source of amusement on the farm radio in Indiana.  XEAW, weighing in at only 100,000 watts was one of the lower powered border blasters.  Some operated with power of up to 500,000 watts.  At one time, Brinkley was the owner of the most powerful radio station in the world,

The problems caused by the “Border Blasters” were largely solved in 1941 by the North American Radio Broadcasting Agreement.  Unlike Canada and the United States, Mexico had never been assigned any “clear channel” stations, and it therefore had little incentive to rein in powerful stations like XEAW.  The new agreement assigned clear channels to Mexico, on 800, 900, 1050, 1220, 1550, and 1570 kilocycles.  To make room for the new channels, the broadcast band was extended upward from 1500 to 1600 kilocycles.  As a result, most American stations changed frequencies (usually moving up the dial) the morning of March 29, 1941.  At that point, WCFL moved from 970 to 1000 on the dial.  It remained there as WCFL until 1987, when it became WLUP and later WMVP, which still inhabits 1000 on the dial.

Presumably, after 1941, WCFL’s listeners north of Milwaukee no longer had to worry about goat testicles interfering with their concert listening.

After the 1941 agreement, “Border Blasters” didn’t completely go away.  For example, Wolfman Jack famously broadcast on XERF, Ciudad Acuña, Mexico, in the 1960’s.  XERF went on the air in 1947 using the facilities of one of Brinkley’s old stations, which had been seized by the Mexican government in 1939 and had been dark for eight years.  XERF, however, operated on 1570, in full compliance with the 1941 agreement assigning this channel to Mexico as a clear channel.

References

Border Radio at Texas State Historical Association

Border Blaster at Wikipedia

1934 station of U3EB, later reassigned call U1AP, Leningrad.

An Interesting article detailing Amateur Radio in the Soviet Union 80 years ago appeared in the October, 1934, issue of QST. If you’re an ARRL member logged in to your account, you can download the full article.

Even during the height of the Cold War, Amateurs in the Soviet Union communicated freely with Amateurs in the rest of the world, and they had a well-deserved reputation of being excellent operators, often dealing with severe equiipment limitations. An excellent 1965 MIT paper describing Soviet Amateur Radio during the Cold War is also available online.

The 1934 article was written by physicist John D. Kraus, W8JK (1910-2004). Kraus likens the state of Soviet Ham Radio as being roughly equivalent to that in the U.S. about a decade earlier. The typical receiver was either two or three tubes, with one serving as detector and the second as audio amplifier. A third tube as a tuned RF stage was popular. Transmitting tubes of 20-150 watts were available. Crystal control was becoming popular, but simpler designs were still more common. The most popular antenna was a single wire known as the “American type.”

The author noted that very few Russian hams spoke English or German, and that his Russian was also almost non-existent. During his travels, he normally made use of an interpeter, but he could often bypass the interpreter by whistling CW and using standard radio abbreviations.

I guess if you really had your heart set on building a one-tube radio 75 years ago, this one might provide some amusement. It’s from Popular Mecahnics, October 1939.  It is, indeed, a radio, and it has one tube.

As you can see from the circuit, it’s basically a crystal set with an audio amplifier. The audio amplifier uses a 25A7GT, which is a pentode and rectifier in the same glass. To run the 25 volt filament from 110 volts, it relies on a line-cord resistor. The cord to the set does double duty: In addition to supplying 110 volts for the B+, it has a second conductor made of resistance wire to power the filament, and just maybe set fire to the curtains if it gets too close. In fact, this type of line cord was popularly known as the curtain burner.  And as you can see, the chassis is “hot.” If the switch is turned on, there’s a 50/50 chance that you would get zapped by 110 volts if you touched the chassis while also touching anything that was grounded.  (According to the pictorial diagram, the antenna ground is not hooked to the chassis, so it wouldn’t provide any safety).

Like any crystal set, the radio requires an external antenna and ground. It has no main tuning condenser. Instead, “the set is designed primarily to receive the ‘best’ broadcast station in any given area,” and you just tuned it once with a small trimmer condenser.

There’s no volume control, but if that station comes in too loud, you can just detune it a little bit.

If you want to build a replica of a vintage one-tube radio, there are probably a lot better choices. But for a beginner 75 years ago who wanted to work his way up from a crystal set, this one was certainly an option. I just hope that his parents warned him to keep the thing away from the curtains and not plug it in near the bathtub.

First issue of Popular Electronics

Sixty years ago this month, the very first issue of Popular Electronics magazine, October 1954, rolled off the presses of the Ziff-Davis Publishcing Company.  The complete issue is available online along with millions of other pages of old radio and electronics publications at
americanradiohistory.com.

Transistors were already on the horizon, since the issue contains an ad from Raytheon for the CK-722 transistor, along with the offer, “Raytheon will supply you with complete information free. Just write to Department P.”

There’s a guest editorial from ARRL president Goodwin Dosland, W0TSN, extolling the virtues of Amateur Radio, the international hobby. Robert Hertzberg, W2DJJ, gives some pointers on getting the ticket in Part 1 of “So You Want to be a Ham.”

Carl and Jerry Stories at Amazon

Construction projects include a four-tube bicycle radio (powered by a 90 volt B battery and 1.5 volt filament battery), a fire alarm (with low melting point alloy sensors), a light meter, and a code practice oscillator.

For those who want to dabble in servicing radios, there are two articles on how to align or repair an AM radio, although one cautions that beginners should steer clear of FM and TV receivers with their more complex circuitry.

The first “Carl & Jerry” story by John Frye also appears in the issue.