Special thanks to Ray Robinson for sharing the Wavescan script with our readers
Part 1
Jeff: The era of High Fidelity radio stations in the United States was an experimental era that lasted for approximately ten years and it was the forerunner for the now widely accepted FM system. This High Fidelity experimental era was made up of two specific time periods, and two widely different broadcasting bands. Let's go back to the beginning. Here’s Ray Robinson.
Ray: Thanks, Jeff. Back in the early 1930’s, reception of radio broadcasting stations in the regular medium wave band, stretching from 540-1500 kHz as it did in those days, was subject to the problems of static, and interference caused by long distance coverage at night. In an attempt to correct these problems and to produce a better quality radio signal on the local scene, some radio stations began to experiment with a high fidelity system, which included a wider bandwidth, the usage of higher frequencies, and the installation of a very high antenna system. In this way, it was hoped there would be less atmospheric and man-made static, and the signal would not be affected so much by the variables associated with day time and night time coverage.
The two bands that were in use were the top end of the medium wave band stretching from 1510 to 1600 kHz, and high frequency channels usually in the 9 metre and then the 7 metre ultra-shortwave bands, or what we would today recognize as part of VHF Band I. The two time periods were from 1931-1937 before commercially made receivers were available for this Apex band, and then 1937-1942 when commercially made radio receivers incorporating the high frequency Apex band became available.
The very first station to install a transmitter in the high frequency Apex band was the CBS station, W2XDV, in New York City, which was inaugurated on February 6, 1932. This station emitted just 50 watts and was on the air experimentally and spasmodically with a relay from the medium wave station WABC, now identified as WCBS. The transmitter was installed in the CBS headquarters building in Madison Avenue, New York City.
The very first station to commence a regular broadcasting service in the high frequency Apex band was W8XH in Buffalo, New York, with a relay from the well-known medium wave station WBEN. This was in the year 1934. On November 3 in the following year, 1935, the aforementioned W2XDV-WABC introduced a regular broadcasting service on the Apex channel 31,600 kHz. In the following year again, 1936, station W9XAZ in Milwaukee, Wisconsin was the first Apex station to originate its own specific programming in this High Fidelity broadcast band.
In 1937, radio receivers which included the high frequency Apex band began to appear on the American market. One of the most notable of these receivers was manufactured by McMurdo Silver, and they issued innovative advertising to this effect.
At this stage, the FCC allocated a total of 5 MHz bandwidth for Apex broadcasting, and this section of the radio spectrum ran from approximately 41 to 44 MHz. The station lists of this era show that 22 Apex stations were on the air.
In early 1939, the FCC issued a dozen additional licenses for Apex stations, though around this time they advised radio broadcasting stations in the United States to consider the implementation of the alternative FM system, which was far superior to the Apex High Fidelity system.
On June 15, 1940, the FCC issued licenses for three more Apex stations, the last licenses that were ever issued for radio broadcasting in the Apex high frequency band. The last station to leave the Apex band and convert to the new standard FM band is believed to be station WBOE in Cleveland, Ohio, and this event occurred in February 1941.
At the height of its popularity in late 1938 and early 1939, there were somewhere around fifty or sixty radio stations nationwide on the air in the Apex High Fidelity high frequency bands. During the ten year period in which Apex broadcasting was in vogue, there was a total of a little more than one hundred different stations on the air at some time during this era.
Many of these stations were heard at a great distance, and radio magazines in Australia and New Zealand show that at least thirty of these stations were heard "down under." These stations also issued QSL cards, and Dr. Adrian Peterson’s Heritage Collection contains at least a dozen.
However, at the same time as High Fidelity broadcasting was taking place in the high frequency ultra-shortwave bands, a similar attempt at quality radio transmission was taking place at the top end of the medium wave band, running from 1510 to 1600 kHz. Stations were allocated a wider bandwidth to accommodate higher audio frequencies, and this experimental era began in 1934, just two years subsequent to the launching of experimental High Fidelity broadcasting in the ultra-shortwave bands. The first four stations on the air in this section of the spectrum were:
Call kHz City State
W1XBS 1530 Waterbury CT
W9XBY 1530 Kansas City MO
W6XAI 1550 Bakersfield CA
W2XR 1550 Long Island City NY
However, the total number of broadcasting stations in this segment of the electronic spectrum was quite small, maybe just a dozen or so. These stations also issued many QSL cards to listeners. In fact one station, W9XBY in Kansas City, Missouri, numbered their QSL cards, and we have seen one card with a serial number as high as 4027.
Now, at the same time as High Fidelity broadcasting was being developed during the 1930’s in the twin areas of the electronic spectrum, at the end of the medium wave band and in the Apex ultra-shortwave bands, so also was experimental broadcasting using the FM, Frequency Modulation system. At this stage, the FCC recommended the usage of FM for high quality radio broadcasting.
Thus, in 1940 and 1941, both of the earlier systems were abandoned; High Fidelity in the upper end of the medium wave band and Apex in the ultra-shortwaves. However, if you look at the radio dial of receivers manufactured in the late 1930’s, you may still find a radio receiver that tuned one of the Apex bands, a symbol of a bygone era.
Apex Radio Stations Worldwide - Part 2
Jeff: Last week in Wavescan, we presented the story of experimental radio broadcasting on the part of Apex radio stations in the United States. This week, we continue the story of Apex radio broadcasting stations in other countries around the world, and also take a look at other later efforts to improve the technical quality of AM radio. Here’s Ray Robinson.
Ray: Thanks, Jeff. The purpose of the experimental Apex broadcasts in the 1930’s was to determine the effectiveness of transmissions on a very high frequency from a very high antenna, hence the name Apex. It was considered that these two factors combined, high frequency and high antenna, would reduce the effect of static caused by man-made electrical interference and by thunderstorms, as compared to in the standard medium wave band.
Even though the United States played the most prominent part in experimental broadcasting in the Apex band, this experimental era actually began in Australia, not North America. Sometime during the year 1931,perhaps as early as May 1931, the AWA radio organization installed a low-power transmitter in Sydney on a frequency somewhere in the 7 metre band (in what is today VHF Band I). The programming was a relay of the Sunday broadcasts from their shortwave station, VK2ME, located at Pennant Hills, an outer suburb of Sydney, New South Wales, though no specific callsign was allocated to this 7 metre transmitter.
It had long been thought that these experimental AWA broadcasts in Australia on 7 metres were in the FM mode, but a closer investigation demonstrates that instead, they were in the AM analogue mode, using a very high frequency, equivalent to the American Apex transmissions. The original series of test broadcasts, using only the Pennant Hills callsign VK2ME, lasted possibly a couple of years, but because no commercially-made receivers incorporating the Apex band were available, the tests were abandoned.
However, five years later, when Apex broadcasting was catching on in the United States, AWA re-commenced similar tests with an antenna located on top of a downtown department store, using a transmitter under its own licensed callsign, VK2MA. Programming was again a relay from shortwave VK2ME, and at times from medium wave stations in the Sydney area. The last broadcast from "Apex" VK2MA was on Monday morning, August 28, 1939.
This station was heard at times in the United States and QSL cards were issued.
During 1932, when stations in the USA were just beginning to experiment with Apex transmissions, station listings of the era suggest that four other countries were engaged in experimental broadcasting on very high frequencies – Canada, England, Germany and Russia.
The Canadian station was located at Bowmanville, Ontario, and used the callsign VE9GW. This station began life as a commercial facility, used for both radio broadcasting and communication purposes. When it was broadcasting radio programming, it relayed medium wave CKGW. VE9GW was subsequently taken over by the Canadian Radio Commission and re-designated with the callsign CRCX.
Anyway, the high frequency registered for use by shortwave VE9GW was 24380 kHz, in the 12 metre band.
In England, the Marconi shortwave transmitter G5SW located at Chelmsford, 30 miles north east of London, was licensed for experimental broadcasts on a channel in the 11 metre band. In those days, it was not realized that the 11 metre band could be effective for international broadcasting during years with high sunspot counts, but rather it was considered to be useful for high fidelity ground wave broadcasting in the station's primary coverage area. Little is known about the results of these test broadcasts from station G5SW in England.
Other stations that were listed as on the air during the year 1932 were located in Berlin, Germany, and Moscow, Russia. The schedule for the German station was for a short period of time on Tuesdays and Thursdays in the 7 metre band; and the Russian station, in the even higher 5 metre band under the callsign RW61, was simply listed as "broadcast".
During the following year, 1933, two more stations came on the air in this high fidelity mode in these high frequency bands. Indonesia, as it is now known, was listed with station PK4PA with experimental transmissions on 5 metres; and Italy was listed with station IAF with experimental transmissions on 10 metres.
The final batch of countries, five in total, in which experimental transmissions were carried out in the very high frequency bands were located in South America, Europe and Asia, all listed in 1935. In South America, Argentina was listed with stations LQK and LQL at Monte Grande on 7 metres, and Chile with station CEC in the 13 metre band. In Europe, France was listed with station TYZ in the 8 metre band, and Madrid, Spain was listed with station EDS in the 13 metre band. In Asia, station HSJ in Bangkok, Thailand was shown as on the air in the 12 metre band.
Interestingly, during the time when station VK2MA was on the air in Sydney, Australia in the 7 metre band, a local radio monitor made the observation that no other stations anywhere in the world were on the air on these very high frequencies, apart from Australia and the United States. While it is true that low-power transmissions on these very high frequency bands would not have propagated very far, the station listings during the 1930’s show quite clearly that there were indeed numerous stations on the air in what was known in America as the Apex band.
Nevertheless, the Apex concept, using a high frequency transmitted through a high antenna, was abandoned when FM broadcasting took over in the early and then later 1940’s. Interestingly, FM stations these days also transmit at the high frequency end of the shortwave bands, and one of the major parameters in measuring the effective coverage area for an FM station is by the height of the antenna system.
Of course, that wasn’t the end of the hunt for high fidelity stereo broadcasting on AM. In 1956, LM Radio in Mozambique experimented with a series of stereo tests on shortwave. These were the first such tests in southern Africa, and probably the first on shortwave, anywhere in the world. Two frequencies were used in the 60 meter band, one for the left channel and the other for the right. This meant that the audio was given twice as much bandwidth as would normally be the case, but a listener had to have two separate receivers to achieve the stereo effect. Since not many households had more than one radio in those days when transistor radios were only just coming on the market, these tests were not pursued.
Then twenty years later in 1977, another attempt was made at facilitating high quality stereo transmissions on medium wave when the C-QUAM system was developed by Motorola. This is a system that allows both a conventional Amplitude Modulated audio source and a stereo Phase Modulated audio source to be multiplexed into the same signal, without causing interference and maintaining full compatibility with mono receivers. In 1983, Sony brought out their SRF-A100 AM Stereo/FM Stereo personal radio, as well as the SRF-A1 AM Stereo/FM Stereo Walkman. But by that time, there were four different AM stereo systems competing with each other – Harris, Kahn/Hazeltine, Magnavox and Motorola C-QUAM, and the lack of standardization is what deterred most radio manufacturers from implementing AM stereo. Even though the Canadian Federal Department of Communications mandated in 1988 that any station wishing to broadcast in AM Stereo must do so using the Motorola C-QUAM system, the FCC in the United States refused to make a ruling, preferring instead to take a ‘laissez faire’ approach and let the market decide the winner.
Although that approach really spelled the death of AM stereo, there are still about 45 AM broadcast band stations transmitting C-QUAM stereo signals in the USA and Canada today. There is also one station that uses the standard in Rome, Italy – Broadcastitalia which since 2014 has been using a Motorola C-QUAM exciter with a Nautel transmitter on 1485 kHz.
In the mid-1990’s, DAB was developed as a new digital radio standard, but it was not compatible with existing analog AM radio, and therefore it required its own frequency range which varied by country, but was typically around 175-240 MHz in VHF Band III. Although the DAB standard has been improved technically since it was first launched, it has not been widely adopted, and a number of countries which did start using DAB have since turned it off, including Canada, Finland, Hong Kong, Portugal, Ireland, Hungary, Romania and Sweden.
In North America in the late 1990’s, a competing digital system was developed by iBiquity - the proprietary HD Radio system. This WAS selected by the FCC as the digital audio broadcasting method for the United States in 2002. It is an IBOC, or In Band On Channel, system, which can be used in both the standard medium wave and FM bands with stations able to transmit hybrid analog and digital signals on the same frequency. While HD Radio has been widely adopted by FM stations in North America, on the AM band there are now very few stations still using it, due to problems with skywave propagation at night. Those AM stations that do still use it generally have to turn it off at dusk and back on at dawn. There are currently only two stations in the whole of the United States using digital-only HD on AM – WWFD in Frederick, Maryland and WFAS in White Plains, New York.
And then finally, there came DRM – Digital Radio Mondiale. That was developed in the early 2000’s, with the very first DRM broadcast taking place in June 2003. This system can be used on medium wave, shortwave and FM frequencies, and has been most successfully adopted in India, where availability on car radios is now standard. But globally, because of the lack of consumer radios that can receive DRM broadcasts, this system has still only been adopted by a handful of international broadcasters, and on a part-time basis at that. There is no doubt that DRM is the superior system technically for digital radio, but with the growing popularity of podcasting and webstreaming, it is now probably too late for any of the current competing systems for digital broadcast radio – DAB, HD or DRM – to establish themselves as a global standard.