Tag Archives: Radio Nostalgia

Bob’s Radio Corner: Where it Began – The AM Medium Wave Broadcast Band

Copilot Radio, Model Unknown
The dial certainly has some problems, but the rich, Bakelite, art deco cabinet is superb.

By Bob Colegrove

One of the great attractions of the radio hobby is that it has so many different areas on which to specialize. As examples, one can focus on a particular band, collect or restore radios, DX or just listen. With so much to choose from, one can impulsively skip from one area to another. I have tuned the shortwave bands for many years, but I also like the AM medium wave band. If there is a purpose to this post, it is simply to bring some occasional attention to AM listening and DXing. There is nothing new in what follows.

What’s in a Name?

To start with, this subject is somewhat confusing by calling it what we do. There are at least three common terms for the electromagnetic spectrum between 530 kHz and 1700 kHz: 1) AM, 2) broadcast band, and 3) medium wave. This poses an identity dilemma; that is, none of these names are exclusive. AM defines a form of modulation, amplitude modulation, which is used in other portions of the spectrum. The same may be said of broadcast band. There are several international broadcast bands within the shortwave spectrum. That leaves us with medium wave. But that term lacks precision. What exactly are the boundaries of medium wave? Shortwave bands have relatively precise names related to their wavelength, 80 meters, 31 meters, etc. Should we call medium wave the 176-thru-943-meter band, instead? Let’s just stick with any of the old familiar terms.

In the Beginning

I’m sure many readers share the experience related here. Even before shortwave there was medium wave. Our initial encounter may have been with the monolithic, multi-band console radio in the parlor. However, the house was likely home to one or more less pretentious table radios, which were limited to the medium wave broadcast band. It all began with curiosity about what lurked in the relative space between the few local stations that played so clearly along the dial. We likely found less listenable stations poking through in the inter-station space. These were stations like our own in neighboring communities. Then, at night, a strange thing happened. Like stars in the sky, more stations appeared, some hundreds of miles away. At the same time, some of the stations we heard during the day disappeared, maybe even a local station or two.

Well, one thing led to another, and soon we were keeping track of stations that we heard. We took note of where they were located and their position on the dial using a new term called kilocycles. The fastidious among us kept daily logs with dates, times, and reception conditions. So, our DXing career began.

I came along a full generation after the advent of AM radio broadcasting. In my early years, it was still the mainstay of public information and entertainment. Television stations were beginning to pop up across the country one by one, and FM radio’s popularity was still a decade away. Like any imposing distraction, there was curiosity in what was being heard and, in the case of radio, where it was coming from.

Our house was home to perhaps three or four AM radios. At the age of seven, I was gifted of a 4-tube Sears Silvertone – mine to keep in my own room. But the radio that really got me going came along several years later and belonged to my father. This was a General Electric Model P755A, five-transistor portable. Shaped somewhat like a lunchbox, including the handle, it was the quintessential portable radio that the world had been waiting for. It ran for many hours off a single, but pricey 9-volt carbon-zinc battery. There was purposely no provision to run it from AC power. Also, it used an internal ferrite core antenna. There was no jack or terminal for an external antenna. Besides the tuning knob and volume control, it had a jack for a single earplug. It was truly portable in all respects. For all its simplicity, it did its job very well, and I borrowed it whenever the occasion presented itself.

Left: Silvertone Model 132.818-1, Sears, Roebuck & Co (1949, $11.95)
Right: General Electric Model P755A Transistor Portable (1957, $19.95)

As an only child, I was the sole recipient of any goodies that came along, and it wasn’t too long before I had my own comparable Westinghouse portable. But the GE was really the one that got things started.

A Plethora of Stations

I have recently wondered whether shortwave use has contracted about as far as it can go. This is not the case with AM, at least not yet. The graph below shows the total number of AM radio stations in the US throughout history, 100 years. The total has remained relatively stable since 1960, albeit with a slight downward trend from the peak around 1990. Stations occasionally come and go. Some rebrand with a different format or fresh call letters. Note that the steepest rate of decline, 217 stations, occurred over the past five years, amounting to 4.7%. Whether this rate of attrition will continue is a matter of speculation.

Graph compiled from https://en.wikipedia.org/wiki/Radio_in_the_United_States

Medium wave DXing is a lot different than shortwave. The density of stations will vary depending on what part of the world you live in. Here on the East Coast of North America, the AM band is saturated with signals. That is, with a suitable antenna, one can at least detect a station on each of the 118 available channels – certainly at night and possibly even during the day. On the other hand, some years ago, I had an opportunity to visit Honolulu, Hawaii. With little time to listen, I only heard a few of the islands’ stations but imagined what possibilities nighttime Dxing held.

Despite the density of stations on the East Coast, there will still be limits on the number of stations logged. My experience is that initially the log grows quickly, then tapers off steadily as you go along. Your time is eventually spent locked in on a local or regional frequency, waiting for something you’ve heard to fade out and something you haven’t heard to fade in. In a previous posting, I worked the lower end of the band rigorously for some time, coming up with a fair number of catches.

Ten-kHz channel separation is the convention in Region 2, the Americas. There have been some occasional anomalies. Several years ago, there was a handful of so-called “split-channel” nonconformists, who placed their carriers midway between channels and presented an opportunity to log some hard-to-hear countries. It was also possible to pull in a few very high-power European and North African stations. This took advantage of the 9 kHz vs. 10 kHz channel spacings between Region 1 (east) and Region 2 (west).

Seasonal changes are also important. Winter is the best. Propagation is generally better and more consistent. Atmospheric noise is minimal. Local stations limited to daylight operation have shorter hours. The gray hours around sunup and sundown can produce unusual DX conditions.

Programming

Programming has changed since the 1950s. As the go-to medium for public information and entertainment, content was original and competitive. Mornings were often filled with local DJs playing occasional songs and generally keeping listeners apprised of news and weather. Traffic helicopters were still in the future. The genre of soap operas was born and consisted of 15-minute, serialized dramas one after the other during the middle of the day. Faithful audiences followed these melodramas for many years. DJs took over the airwaves again in mid-afternoon and continued through dinner time. Prime time lasted throughout the evening hours with regular drama, comedy and variety shows which were networked throughout the country. Continue reading →

Bob’s Radio Corner: What Is It About Radio Dials?

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– Recollections of Bob Colegrove

In the late ‘60s, I worked as a mechanical assembler at Communications, Electronics Inc. (CEI) in Rockville, Maryland (acquired by Watkins-Johnson Company). We produced military-grade receivers, mainly for the military (whom else?). These covered the spectrum from VLF through microwave. It was the early days of electronic digital readouts. There were no LEDs or LCDs. Instead, some of our models featured the Numeric Indicator eXperimental, or “nixie” tubes. These were glass tubes filled with low-pressure neon/argon gas, featuring stacked wire cathodes shaped like numerals (0-9) and a mesh anode. An analog-to-digital circuit encoded the frequency to illuminate the correct digits.

Below is shown a DRO-50 Digital Readout from the 1968 CEI catalog. It contained 6 nixie tubes for the frequency display, and the unit had an accuracy of ±100 Hz. Interestingly, this frequency display was designed specifically for the Hammarlund SP-600 Receivers (R-274A/FRR (Army), R-274B/FRR (Navy)). I never saw a DRO-50 come across our line and suspect it may not have gone beyond the prototype. About that time, the SP-600s were ending their military service, so there wasn’t much of a market for upgrades. It would still be a few years before I owned an SP-600 of my own, but how would I love to have one fitted with a DRO-50.

What I had instead of nixie tubes were variable capacitors or inductors, which changed the tuned frequency through a kluge of pulleys and strings, all these hidden behind a Raymond-Loewy-designed bezel and operated by the tuning knob.

What was visible on the front of the radio was an irregular representation of frequencies covering the tuning range of the radio, in other words, the dial. As you rotated the tuning knob, you set the whole tuning mechanism in motion. Signals were progressively tuned, processed, and reported through the speaker or headset as you advanced higher or lower.

Somehow the frequencies never quite agreed with the numbers or divisions on the dial. It could be that the circuits inside the radio were out of alignment. Just as likely, the design of the dial was determined using a preproduction prototype which could not possibly account for the tolerances of the components used on the assembly line.

Consider the figure at the beginning of this posting. It is a portion of the dial on a Hallicrafters S-38E – magnified somewhat. The full dial on the E model was big and bright. It extended across the front panel of the radio and presented frequency readout about as well as was possible. Nevertheless, there were real shortcomings.

The figure is not only typical if communication receivers of the time but also living room console radios of an earlier period. Take the 31-meter band as an example. Broadcast stations were bunched roughly between 9400 kHz and 9800 kHz. At 5-kHz channel spacing, this resulted in roughly 80 channels. Of course, not all were in use at any given time, but still a smidgeon turn of the knob could traverse two or three stations.

This situation was relieved somewhat on communication receivers by the addition of a bandspread – a separate tuning mechanism which could effectively magnify a small portion of the main dial. The idea was to place the main tuning dial at the high end of the desired band and the bandspread at 0. Then, by tuning the bandspread toward the other end, lower frequencies could be tuned with greater separation.

Since the bandspread could be used at any place within the tuning range of the radio, a separate dial became a problem, so it was usually annotated with a simple logging scale incremented linearly from 0 to 100. Thus, one had to compile a log-to-frequency conversion table or graph to interpret the frequency. More sophisticated receivers could display the 80- through 10-meter ham bands on the bandspread dials.

As an example, I located some notes made in 1959 using the S-38E. The table shows the frequency, bandspread reading, station and country. Thirty-one meters was an easy match for the bandspread, as WWV on 10000 kHz was a steady marker which you could use to calibrate the bandspread with the main tuning. For all practical purposes, the band was bounded by the Voice of Spain on 9360 kHz and R. Budapest on 9833 kHz. For many years, Tel Aviv was an outlier on 9009 kHz.

Alternately, one could construct a graph as shown below. Unfortunately, most inexpensive radios did not produce linear tuning, so you couldn’t simply draw a straight line between two points on a graph and expect to interpolate the intermediate frequencies with accuracy. Instead, graphs were constructed laboriously by hand adding intermediate points for known frequencies. The figure shows the resulting parabolic function where the slope is greater on higher frequencies and gradually levels off as the bandspread is tuned lower. Notice that most of the activity was mashed between 40 and 60 on the bandspread, then compare this with the picture of the bandspread above.

On the S-38E a bandspread was something of an improvement, but not the complete answer. The problem only got worse as you went higher in frequency. At 19 and 16 meters the band compression became quite severe.

Our esteemed leader, Thomas, occasionally uses a picture of the dial shown below as a lead figure of a posting. It is possibly an RCA Victor Model 110k console radio. When I see this, I think, who wouldn’t give a king’s ransom to own that radio in its fully restored condition? Note the 31-meter band has been magnified as its own separate band and appears in a near linear progression. Thirty-one meters was arguably the center of international shortwave broadcasting in the golden age.

Have you ever wondered what the rest of that radio looks like? Here’s one in sore need of some Pledge. Now imagine yourself, perhaps 11 or 12 years old, perched in front of it on your grandmother’s needlepoint stool tweaking the dial. If you have experienced this, no explanation is necessary. If you haven’t, none is possible.

Source: https://www.liveauctioneers.com/

So, as it turns out, I have tempered my earlier conviction that a digital frequency readout is necessarily better than a classic dial. Not to say you can easily pry the PL-880 with 10-Hz resolution from my cold, stiff hands, but I have come to realize that intrigue and mystery of shortwave listening rested in the uncertainty of knowing exactly what frequency you were on. There was always the possibility that the elusive Nibi Nibi Islands lay somewhere near the shadow cast by the dial pointer. It was a land of enchantment, and once you left its borders, you could never return again.

A DXer Looks Back at the Voice of America

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by Dan Greenall

50 years ago, Voice of America broadcasts could be found all over the shortwave dial.

In addition to a number of transmitter sites located stateside, the VOA used to broadcast from a number of other facilities located in overseas countries in order to help get its signal into all corners of the globe. Many of these “relay” stations made for challenging DX catches and there was even an award offered by NASWA to those providing sufficient proof of reception of them all. An example of this can be found on this link: https://k5nd.net/2011/06/voice-of-america/

The familiar tune of Yankee Doodle (heard at the beginning and end of a transmission) along with station ID in English would often include the particular transmitter site in use. Several old recordings of these can be found on my links to these on the Internet Archive.

Technical staff hired to help maintain equipment at overseas facilities were often licensed amateur radio operators. See the attached scans of two QSL cards from amateurs who worked at the station near Monrovia, Liberia.

Most of the various VOA transmitter sites are listed below. Some include links that will lead to related historical information, articles and/or photographs and are well worth exploring.

VOA Greenville NC

VOA Bethany OH

VOA Dixon/Delano CA

VOA Marathon, FL

VOA Wooferton UK

https://www.bbc.com/news/uk-england-shropshire-67133389

VOA Kavala Greece

VOA Thessaloniki Greece

VOA Rhodes, Dodecanese Islands

http://www.theradiohistorian.org/courier/courier.html

VOA Monrovia, Liberia

https://www.africabib.org/rec.php?RID=099870371

VOA Tangier, Morocco

VOA Okinawa, Ryuku Islands

http://jandd.org/photo_gallery/voice_of_america_on_okinawa.htm

VOA Poro/Tinang, Philippines

https://www.radioheritage.com/voice-of-america-relay-station-at-tinang-in-the-philippines/

VOA Udon Thani, Thailand

https://www.udonmap.com/udonthaniforum/viewtopic.php?t=54733

VOA, Sri Lanka

https://mt-shortwave.blogspot.com/2017/03/final-end-of-another-voa-relay-station.html

VOA Sao Tome

VOA Botswana

A year ago, in January 2025, I made a couple of recordings, using remote SDR receivers, of some Voice of America programs being broadcast from their Botswana transmitter site. These have been uploaded to archive.org and can be found here: https://archive.org/details/voa-africa-via-botswana-relay-january-19-2025

Since March 16, 2025, it seems the only former VOA transmitters being used are Greenville, NC (Radio Marti), Tinang, Philippines (Radyo Pilipinas world service), and Wooferton, UK (BBC and others).

Taiwan on Shortwave – Then and Now

Video: When Shortwave Radio Connected Soldiers Overseas with Their Families in WWII

1 Reply

Many thanks to SWLing Post contributor Fred Waterer, who writes:

“The History Guy” (a terrific YouTube channel) talks about the technical marvel of uniting the four radio networks and soldiers overseas via shortwave at Christmas 1942 and 1943.

Click here to view on YouTube.

Anachronism Alert: FM on a Radio in the WWII Blitz?

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Many thanks to SWLing Post contributor Paul, who writes:

Hi Thomas, while watching this documentary from the BBC telling how people Northern Ireland survived the Blitz in World War 2. I spotted this glitch. The picture is from a scene when Prime Minister Neville Chamberlain declared war on Germany.

It will be noted that the radio’s dial has an FM band. FM broadcasting commenced in the UK in 1955.

Cheers

Paul
Christchurch,
New Zealand

You’ve a keen eye for detail, Paul. Thanks for sharing.

Vatican Radio – Then and Now

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Many thanks to SWLing Post contributor Dan Greenall, who shares the following post:

When I began shortwave listening back in 1969, Vatican Radio was one of the first stations I came across. That same year, the late Dr. Richard E. Wood authored a book called “Shortwave Voices of the World” in which he writes some notes about the station that you can read here [PDF].

In fact, Vatican Radio was established in 1931 by none other than Guglielmo Marconi. It wasn’t until sometime after World War 2 that the present-day transmitter site was set up at Santa Maria di Galeria. A nice view of it is pictured on this 1970 QSL card.

By the early 1970’s, short English language broadcasts to North America were still included in their schedule as you can see from these pages in the 1972 World Radio TV Handbook [click to enlarge].

In 1983, Ken MacHarg, a former host of the DX Partyline on HCJB, was the author of a now out-of-print book entitled “Tune In The World”. Read Ken’s comments about Vatican Radio here.

Though their published interval signal (see WRTVH) was “Christus Vincit”, Vatican Radio could also be recognized by the bells of St. Peter’s, which you will hear in this recording from 1971 that I made from my listening post in Ontario, Canada: https://archive.org/details/vatican-radio-1971

In more recent times, I have read that shortwave broadcasts to North and South America, as well as Europe, ended in 2012. In addition, English language shortwave transmissions to Asia ended in 2017, though they could still be found online. A list of their current English language broadcasts, as found on short-wave.info is shown here:

Here is a recording made August 11, 2025 using a remote SDR in the UK, complete with “Christus Vincit” interval signal, as they began their African service on 9705 kHz.