First Band, Top Band

On 20 March 1923 Secretary of Commerce Herbert Hoover convened his second national radio conference and, as before, the ARRL was there in force. A May QST photo shows Maxim at center flanked by C. F. Jenkins, identified as “inventor of radio transmission of photographs,” and Major General G. O. Squier, US Army, Chief Signal Officer. Paul Godley of transatlantics fame and ARRL Secretary Kenneth Warner can be seen in the background. Besides Maxim and crew, other prominent participants from the radio research community included inventors Edwin Armstrong, Louis Hazeltine, Professor C. M. Jansky—amateurs all—and many others from government, academia and industry.1

QST May 1923 p. 12 (Maxim, et al)

Maxim at the conference, with Godley and Warner behind

The majority of the attendees, however, represented the broadcasting industry, as expected. After all, the conference’s main purpose was to determine what could be done to ease the industry’s interference problems by establishing new regulations deemed permissible under the current law, now eleven years old. Since the previous year’s attempt at legislation had failed, this was the only path left.

To accomplish any meaningful relief, other services had to give up spectrum space to create new wavelengths for the broadcasters. Recommendations included reclaiming the 450-meter maritime wavelength and the amateur extension at 275 meters to create a continuous broadcast band from 222 to 545 meters (approximately 1,351 to 550 kHz, which is very close to today’s AM broadcast band limits). The “government reserve” allocation above 600 meters was then recast to include the maritime service that would be displaced from 450 meters.

The broadcast band was further divided between Class A stations, those with high power and continuous service, and Class B stations “of restricted range and ability.” Class B would operate below 286 meters where wavelength assignments would be made on a geographical basis so as to minimize interference.

Assignments for Class A stations above 286 meters would be handled a bit differently. One wavelength would be assigned exclusively to each geographical region, and stations in that region would further divide up the use of the channel into time slices. The conference asserted that this would make it possible to assign fifty such regional wavelengths spaced 10 kHz apart. With this scheme in place, anyone with a good receiving setup could tune in to various other areas of the country and, conditions permitting, would have some hope of hearing them without interference.

Ten local areas within each of five national zones would have allocations separated by 50 kHz, and no areas in adjacent zones would be closer than 20 kHz. All broadcasters were required to have measuring equipment to ensure that they were operating within 2 kHz of their “assigned wave frequency,” as the rule phrased it.

To ease the transition for an existing broadcaster, a temporary classification could be assigned to allow it to continue to use its present allocation until it could obtain a new one and move there.

The amateurs would get exclusive use of 150 to 200 meters (1.5 to 2 MHz), which is larger than our current 160-meter band—widely called top band by hams. Special license holders would be permitted to operate between 200 and 222, and “extra special” licensed stations could use “some quiet wave below 286 meters for use in the difficult Rocky Mountain region for the benefit of trans-continental relay work.” There could be at most six of these stations—a severe restriction. Spark transmission was tentatively assigned to 175 to 200 meters, with only straight CW allowed between 200 and 220, and CW, ICW and phone between 150 and 176 meters. Further subdivision was possible and the ARRL was asked to recommend allocations by transmission type at a later date. Significantly, everything below 150 meters was designated as reserved but open to special licensing.

The department would also require all radio stations to surpress harmonics to a level yet to be specified. And the conference resolved that spark transmitters should be replaced “as rapidly as practicable by apparatus which will produce a minimum of interference.” It further resolved that amateurs should “by mutual arrangement” observe periods of silence during religious broadcasts on Sundays. To put some teeth into the regulation, it stipulated that the Department of Commerce had the power to minimize or eliminate interference by rescinding licenses, regulating operation and other means.

Although the major conference benefits went to the broadcast industry as intended, nearly all concerned parties were pleased with the outcome and some wondered why the government had not done this a year earlier instead of expending energy trying to get legislation passed. (The answer would become clear a few years later.) The ARRL board was to study the proposed regulations in full and make its own recommendations before they became final.

The conference also asked the ARRL to recommend how the 200–150-meter amateur allocation might be subdivided.2 The League’s board then canvassed the membership across the country to come up with a unified set of recommendations about allocations and other issues that might arise. Although the membership opposed any sort of elaborate subdivision plan based upon signal type, there was widespread support for something that would protect the shorter wavelengths from QRM. So, in a proposal similar to but simpler than the one made by the Conference, the board recommended that all modulated forms of transmission be limited to the band from 176 to 200 meters, and that straight CW be permitted anywhere in the amateur allocation, thus protecting the shorter wavelengths which were increasingly viewed as important by amateurs. (This reversed the previous scheme where, like today, broader modes were confined to shorter wavelengths, that is, higher in each frequency band.)

In a worrisome surprise the Commerce Department began to recall amateur licenses in order to add a stipulation that no transmitting could occur between 7:30 and 10:00 p.m.—an official mandate for the Rochester Plan. Knowing about the ARRL’s voluntary program and realizing that not all amateurs were League members, the Department was trying to “help” but only ended up alarming most amateurs. After the League explained the difference between how amateurs viewed a voluntary program as opposed to a required one, the Department agreed to suspend further action and only apply the new regulation to new licenses until the ARRL Board could consider it. With unanimous objection the Board concluded that such a mandatory regulation was undesirable and, in particular, would obviously prohibit operation during emergencies. The Department’s action would remain pending.

The League also suggested that the amateur allocation be expanded to 220 meters in a more formal manner and establish an “Extra First Grade Amateur Operators License” which would conform to the 1912 law permitting special licenses. Action on this was also still pending. Meanwhile all of the old 375-meter special licenses were being recalled since that wavelength was now part of the broadcast band.

On 28 June the Commerce Department signed approval of the new regulations, designated General Letter No. 252.3 General and Restricted Amateur Radio Station Licenses would permit the use of pure CW anywhere between 150 and 200 meters, with spark, modulated CW and unfiltered CW being restricted to wavelengths of 176 to 200 meters—basically adopting the League’s suggestion. Special Amateur Radio Licenses could extend the use of pure CW to 220 meters. Pure CW was defined as oscillations produced using a power supply of “substantially direct current” such as a battery, generator, or rectified, filtered AC with less than 5% “supply modulation,” the term used to describe any remaining non-DC component. Input power for all three classes was limited to 1,000 watts. Each station license would specify the equipment in use and the restrictions that applied to a specific transmitter (more than one was possible).

Special stations had to be operated by amateurs holding an Extra First Grade Amateur operator’s license,4 a newly established class, or a First Class or Extra First Class commercial license. The new Extra First Grade Amateur license required passing (with a 75% grade) an examination containing a new set of questions, sending and receiving code at twenty words per minute, and two years of experience as an amateur operator, as the League had recommended. General and Restricted licenses were again being recalled for modification, this time to specify wavelength and quiet hours, whereas special licenses were being replaced with newly issued ones to reflect the new allocation.

All licenses would specify that transmitting was not permitted between 8:00 and 10:30 p.m. local time “nor Sunday mornings during local church services.” On one hand, this was recognition of the effectiveness of the voluntary quiet hours in the Rochester Plan, and on the other, observation that it was not being uniformly observed. The later 8:00 p.m. start time was a welcome change.

For the first time, amateurs officially had a band assigned to them rather than a single specific wavelength (200 meters). Although the League did not get the desired access to wavelengths shorter than 150 meters, the Commerce Department assured amateurs that it would grant special licenses to operate there for all applicants who were “seriously interested” in experimenting.

Having a band of wavelengths opened up new possibilities for reducing QRM. Warner optimistically, if unrealistically, suggested that, “we have so many cycles in our band that if we distribute ourselves even approximately evenly we should have almost no QRM.”5 But to take advantage of the space, amateurs needed a technique to make it easier to change wavelength, normally a cumbersome procedure. “This is something we have never developed because it hasn’t been permitted us before,” he noted. A frustrating yet common occurrence was that you would hear a station you’d like to work calling on a different wavelength from your transmitter, then fail to raise him because he was not tuning around with his receiver. The League secretary marveled at “how funny it is to call blindly and hope our correspondent will be kind enough to turn his knobs to our wave; how much more to the point to call on the wave we know he’s listening on!” He cited an example where two stations miss each other, one on 200 meters and the other on 215—a difference of about 105 kHz. And he called for invention by the members, writing that, “We don’t believe there is a circuit whereby it can be done efficiently with even two controls; the couplings have to be changed and it is likely to become a half-hour job” just to QSY!

The second big job was to devise transmitters that produced no spurious emissions—or at least fewer of them. The Commerce Department indicated that it might consider lifting the quiet hours requirement if amateurs could build “a transmitter which is silent on the waves it isn’t supposed to be using, even when listened to next door.” This was an implied reference to interference to broadcast listeners who would likely be using unselective receivers—a broadcaster on 222 meters, for example, is only 150 kHz away from 200 meters. This clearly called for the use of pure CW with no modulation effects of any kind. “When all these things are solved,” predicted Warner, “a bugproof amateur transmitter will be the result; we shall be much happier, our work will be much more pleasant and more enjoyable.”

Ahead of the ARRL board’s upcoming detailed consideration of the new rules, Warner summed up his impressions and suspicions this way:

From the standpoint of the broadcasters it’s FB but from that of the amateur—? It seems somebody else has their eye on the waves below 150 meters and we did not succeed in our effort to secure an amateur band around 100 meters … The majority sentiment on the Conference was to fix up the broadcasting business so it could succeed, and tribute was exacted from the government services; the amateur, the commercial, and even perhaps the facilities safeguarding life at sea, to make that possible.

BT sep smAround this time amateurs began to discuss how band allocations were specified and talked about. Echoing an increasingly popular opinion, QST correspondent A. N. Goldsmith asked how and why wavelength was chosen over frequency to describe radio waves, when frequency was much more “natural”6 in his estimation. After all, nobody referred to AC power as 5,000,000-meter waves. The practice of specifying wavelength probably dated back to Hertz (ironically enough, since his name would later be used internationally as the standard unit of frequency), who was experimenting with waves of only a few meters, and to studies of light waves which had frequencies so high as to be “practically impossible” to comprehend, wrote Goldsmith.

But for radio it seemed a big mistake to think in terms of wavelength. It was much easier to speak about “space for transmission” in terms of frequency, since that amount of space depended directly on the frequency of the modulating signal. Thus the frequency at the center of a signal’s band of occupied frequencies is the carrier frequency. It then becomes easy to say, for example, a 200-meter CW signal at a speed of 20 WPM is on a carrier frequency of 1,500 kilocycles and occupies a band 10 cycles wide. Similarly, a phone signal occupies a band having a width that is double the maximum desired audio frequency, which, Goldsmith asserted, ranges from roughly 4,400 cycles for speech to 15,000 for “high grade music.” The band of wavelengths depends on the wavelength itself, whereas the band of frequencies is the same for a given mode of transmission regardless of the carrier frequency. Using frequency made it much easier to talk about signal occupancy within bands.

This discussion also made clear why spark was on its way out. A spark signal extends out indefinitely from its carrier, getting weaker as you move further from the center. “A well-behaved modern station must have a definite address. It must occupy a certain numbered residence of reasonable width on the Street of Carrier Frequencies, and it may not invade everyone else’s home to some extent. And that is exactly what the spark station unfortunately does,” and why it must be eliminated, wrote Goldsmith. Having used wavelength for so long, it would be difficult to make the change due to “conventional and sentimental objection” to it, he added.  But converting was easy, really—dividing 300 by the wavelength in meters gives the frequency in megahertz. To get the frequency at 200 meters, you divide 300 by 200 which equals 1.5 MHz.

With the arrival of a band and allocations within it, amateurs would have to change both how they produced signals and how they talked about them.

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  1. Kenneth B. Warner, “The Second National Radio Conference,” QST, May 1923, 12.
  2. Kenneth B. Warner, “Amateur Regulations,” Editorial, QST, June 1923, 35.
  3. Kenneth B. Warner, “The New Amateur Regulations,” QST, August 1923, 13.
  4. The first antecedent to the later Extra Class license.
  5. Kenneth B. Warner, “Some Jobs to Do,” Editorial, QST, August 1923, 37.
  6. A. N. Goldsmith, Why Kilocycle?,” QST, June 1923, 32.

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