Category Archives: AM

Bad Signals: Transmitters in need of care

China Radio International via Radio Havana Cuba

Click to enlarge

Each morning, I enjoy listening to Radio Australia on 9,580 kHz, but I’m forced to tune elsewhere due to interference when China Radio International starts broadcasting on 9,570 kHz, via Radio Havana Cuba’s relay.

Hypothetically I should be able to mitigate any adjacent interference from CRI by listening to Radio Australia’s upper sideband. But unfortunately, RHC’s transmitters spew spurious emissions a full 20 kHz on either side of their carrier. It’s most annoying.

Here’s what RHC/CRI’s 9570 kHz signal sounds like on 9560 kHz:

Here’s what my waterfall looked like when CRI signed off:

Notice how clear the 35 kHz waterfall window became (that’s Radio Australia centered on 9850 kHz):

The reason for this is clear: obviously, some of RHC’s transmitters are in need of care–and they’re not the only ones.

Radio Cairo

I’ve received a number of requests from Radio Cairo to post notices about their English language broadcasts. Normally, I’m quite happy to post press releases, but in each case I’ve mentioned that their English broadcasts are almost impossible to understand. For years, RC has had a problem with AM modulation (I assume) and, to my knowledge, have never addressed it.

I’ve sent RC feedback on a number of occasions; in response, I’ve received only the inconclusive reply that they’re “looking into the situation.”

To underscore the point, on Sunday Andrea Borgnino shared the following video/audio of Radio Cairo via Twitter.

Radio Cairo & worst am modulation @SWLingDotCom @LondonShortwave @John_Northants @UlisK3LU pic.twitter.com/o0aRCkPtwt

— Andrea Borgnino IW0HK (@aborgnino) March 20, 2016

There are other broadcasters that emit messy signals, but Radio Havana Cuba and Radio Cairo are the most noticeable in my listening area. And, it seems, neither broadcaster is in any hurry to address their ongoing problems.

In Radio Cairo’s case, especially, the broadcaster is simply wasting money by attempting to broadcast a signal that can neither be received nor interpreted. It’s rather sad. Ultimately, one has to wonder why they bother to broadcast at all…

Radio Havana Cuba, China Radio International, and Radio Cairo (among others) take note: a little care of your radio transmitters will go a long way toward increasing your listenership.

What you can do: Consider contacting broadcasters when when you become aware of transmitter problems. Despite RC’s notable exception, oftentimes a broadcaster may not be fully aware of the issue––thus your feedback is necessary to help correct the problem.

Paul Litwinovich on “The Life, Decline and Possible Rebirth of AM”

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Many thanks to the SWLing Post reader who noted this latest post by Paul Litwinovich at WSHU (Paul is frequently referenced here on the Post).

A short excerpt:

“AM occurs elsewhere in nature. A lightning strike or manmade electrical discharge will produce a burst of electrical noise that varies in amplitude. Since AM radios are designed to detect variations in amplitude, this is why they are prone to interference from such things. AM held sway as the primary method of modulating a radio wave up to WWII, not only for broadcasting, but for all types of radio communications.

Every vintage consumer radio, be it standard broadcast or shortwave, up to WWII, received amplitude modulated signals. Nowadays, AM broadcast stations are associated with lower quality audio, but such was not always the case. Receiver design really came of age in the 1930s with the superheterodyne circuit and advancements in loudspeaker design. The grand floor consoles of the late 1930s leading up to WWII were capable of producing audio that was very good, even by today’s standards, the only exception being that they were monaural, as stereo technology was still a ways off.”[…]

Litwinovich’s article is a must-read as he gives a concise overview of amplitude modulation, AM vs. FM, and even covers current proposed uses of the broadcast band (something we’ve also recently mentioned).

Click here to read The Life, Decline and Possible Rebirth of AM.

KIRO saves radio history by accident

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Many thanks to SWLing Post reader, William Lee, who shared the following story from Mynorthwest.com about how radio station KIRO saved a bit of radio history through “accidental preservation.” Here’a an excerpt:

One of the most important events of the 20th century was World War II. The Cold War that followed and many of the national borders that exist to this day were largely created during that deadly, years-long conflict from the late 1930s to 1945.

An expert speaking at the Library of Congress at the first-ever Radio Preservation Task Force Conference described how one of the most important tools for understanding World War II is available to researchers only because of an “accident” at KIRO Radio more than 70 years ago.

During his keynote address last week in Washington, DC, longtime archivist and librarian Sam Brylawski spoke of KIRO Radio’s role in saving a priceless audio record of American history.

It was a case of “accidental preservation,” Brylawski told the audience of more than 200 radio history scholars from around the US and Canada, that resulted in the creation of a nearly complete archive of CBS news broadcasts during World War II.

“KIRO is the station in Seattle that cut lacquer discs to timeshift,” Byrlawski said, explaining how the scheduling of live broadcasts of CBS Radio’s news coverage was aimed at the Eastern time zone, which was not convenient for West Coast audiences. KIRO, as Brylawski described, violated network radio policies to make recordings of news programs on giant, 16-inch diameter discs, and then play them back a few hours later at times that were more convenient to Seattle-area listeners.

Continue reading the full article and listen to the audio report at Mynorthwest.com…

CBS considering the sale of its radio division

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When Charlie Chaplin finally allowed the world to hear his voice after 20 years of mime, he chose CBS's airwaves to do it on. (Source: Wikipedia)

When Charlie Chaplin allowed the world to hear his voice after twenty years of silent performance, he chose CBS for the broadcast.

(Source: LA Times)

CBS Corp. is poised to exit the radio business that it helped create.

Eighty-eight years ago, the company’s founder, William S. Paley, bought the nascent Columbia Broadcasting System, and those radio stations became the nucleus of a budding broadcast empire.

But on Tuesday, CBS Chairman and Chief Executive Leslie Moonves said the company was exploring strategic options, including a sale or spinoff, of its entire radio division.

“The aim here is to unlock value for our shareholders,” said Moonves, who made the announcement during an investor day in New York.

The decision marks the end of an era and highlights the waning influence of commercial radio, which is no longer considered a growth industry. Young adults spend more time listening to digital music files, podcasts and subscription Internet radio services such as Spotify and Pandora. The shift has prompted major advertisers, including car dealerships, wireless phone companies and financial services firms, to steer more of their marketing dollars to digital platforms.

Continue reading at the LA Times’ website…

Stuart Sizer: Heathkit designer, dad, and “bon vivant”

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Two weeks ago, through a radio preservation group, I met the son of Heathkit product designer of the 1950s-70s, Stu Sizer––”stylist, artist, maker of models, bon vivant.” His son described the discovery of a few vintage Heathkit brochures, photos, and illustrations his father kept in his family’s basement shop, many of which had been scanned at some point.

Stu Sizer––”stylist, artist, maker of models, bon vivant”––was tasked with crafting Heathkit’s user-friendly and attractive exterior designs. For many years Sizer was Heathkit’s only product designer, and was therefore often busy. “He was a great dad,” his son told me, “but he spent a lot of time in the basement proof-building kits.” He adds wryly, “Let that be a lesson to the hams of this world.”

Sizer’s son kindly shared with us the following scans and photos of his dad’s work, many of which are original drawings; the series concludes with some clippings featuring Sizer.

On Stuart Sizer

James adds an LM386 amplifier kit to his Heathkit GR-150

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Many thanks to SWLing Post contributor, James Surprenant (AB1DQ), who shares this update to his review of the Heathkit Explorer Jr. TRF AM radio receiver kit:

With regard to the Heathkit TRF AM receiver kit, I did indeed build my LM386 amplifier.

I was planning on home-brewing it from scratch as the chip is pretty much all you need and there are various proven schematics for the circuit, but in the end I went with a small kit from Nightfire Electronics for $10 plus $5 shipping that I found on Amazon.com.

It was a bit cheaper to buy it in kit form, of course, and then there was the convenience of having all the parts in one place.

Here is a photo of the kit as advertised on Amazon…

And here is my build with the Heathkit…

I modified the kit to add a 3.5mm input jack, replacing the RCA jack that came with the kit, to make it easier to plug into the Heathkit radio.

I deliberated whether to install the audio amp into the Heathkit cabinet drilling out a couple of holes for the pot shafts. It all would have fit and I could have easily mounted the 3″ 8 ohm speaker to the back panel of the Heathkit radio. In the end, I decided to keep the radio original and mounted the amplifier board on a small piece of wood I found at a hobby store and decided to leave it all exposed. It works well, all things considered.

(Click here to view video on Facebook.)

It worked well and per my original review on SWLing Post, I feel Heathkit should have included such a little amp in the kit – it makes a big difference.

Many thanks for the update, James! That little LM386 amp kit seems like an affordable addition for any receiver lacking an amplifier or adequate audio amplification.

Tuning the Scott Marine SLR-M at sea

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Many thanks to SWLing Post reader, Vendel Boeree (K2DSI), who writes:

Hi Tom, I just wanted to compliment you on your fine website. As a kid I would listen to Radio Netherlands which made me quite the hit with mom because she was homesick for our native Holland for quite some time. I was heart broken to find out that Radio Netherlands went dark not that long ago.

Back in 1967 my family moved to Australia and went there by freighter. Things didn’t work out as planned and we returned on an old American freighter, the “African Moon”.

I became friendly with the radio operator on that ship and he let me shortwave listen when he was off watch. The receiver was a “Scott” and appeared to be the same as yours. They also had a “Scott” receiver in the lounge that had a slide rule dial that was used for entertainment purposes. I was hooked. I wanted to be a radio operator.

Needless to say I didn’t follow through on that dream and I suppose that’s just as well seeing as how ROs are a thing of the past.

Take care and keep up the good work.

Vendel Boeree/ K2DSI

Thanks so much for sharing those memories, Vendel! I bet reception was nothing short of amazing while you were at sea. I’m guessing the slide rule model Scott you listened to in the lounge was the model SLR-F (click here for a photo).

Just the other day, my wife looked around my radio shack and asked what radio I would grab if the house were on fire. My answer was the Scott Marine SLR-M. It represents everything I love in WWII era receivers: built like a tank, great sensitivity, beautiful back-lit dial, built-in speaker, phono in, a magic eye and–since it was intended as a troop morale radio–beautiful room-filling audio.

Yep. Scottie’s a keeper!