Category Archives: How To

Radio Waves: Eugène Aisberg, Filter Design, ABC Workers Face Cuts, and Data via Web SDRs

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Radio Waves:  Stories Making Waves in the World of Broadcasting 

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Paul, Marty, and Michael Bird for the following tips:

Eugène Aisberg, Radio Writer (OneTubeRadio.com)

After a wartime absence, the January 1946 issue of Radio Craft carried an article by writer Eugène Aisberg.  While that name might not be familiar to American readers, Aisberg was a prolific author in the early days of radio, and wrote some of the best treatises on radio for the popular audience.  He was fluent in French, Esperanto, German, Russian, and English.

Aisberg was born in Odessa, Ukraine, in 1905, and lived most of his life in France. He was the director of the French magazine Toute la Radio and a prolific author of a number of books. His most popular book, which is still in print, is La Radio? Mais c’est très simple (Radio? But It’s So Simple!)  The book, currently in its 29th edition, an extremely solid background covering all aspects of electronics, and is written in a popular, easy-to-read style. While the book was ultimately translated into several languages, it was apparently never published in English.[…]

Filter Design Software (Nuts and Volts)

If you’ve ever lived close to an AM broadcast station, you probably experienced the phenomenon known as fundamental overload. It occurs when a receiving device is functioning entirely properly but unable to reject a strong signal. The receiver might be a wireless telephone, a scanner, or even a TV or radio receiver. The AM signal is completely legal but just too strong, disrupting the function of the receiver or overriding the desired programming.

[…]Hams often experience fundamental overload on the 160 meter band (1.8–2.0 MHz) which is adjacent to the AM broadcast (BC) band (550 kHz–1.7 MHz). Antennas for those frequencies pick up a lot of AM band RF, overloading the input circuits and creating distortion or false signals inside the receiver. The usual solution is to install a high-pass broadcast-reject filter at the receiver input, attenuating the unwanted AM signals below 1.6 MHz while passing the desired 160 meter signals with little attenuation.

So far, so good, but a filter that doesn’t attenuate signals very much above 1.8 MHz while attenuating them significantly in the adjacent broadcast band is not a simple thing to design. There are tables and equations, but they are tedious to work with. Practically, you’ll need to build the filter with standard-value components as well, and that will affect filter performance too. Sounds like a job for some filter design software, doesn’t it?

There are several filter design software packages ranging from simple calculators to sophisticated CAD programs. Luckily for hams and other experimenters, there are plenty of free or low-cost programs to try.[…]

ABC workers face anxious wait over job, program cuts (The Age)

David Anderson did not mince words at a Senate Estimates hearing last October. “There will be job losses,” ABC’s managing director warned. “It’s not something I can quantify at this point in time. There’s still more work to be done.”

Towards the end of March, Anderson will reveal a five-year plan for the national broadcaster. To the frustration of staff, it’s unlikely to specify which parts of the organisation will bear the brunt of these cuts or how many workers they might lose.

Several senior sources spoke about the situation at ABC on the condition of anonymity, given sensitive funding negotiations are yet to be finalised.

“All these media reports claiming the redundancy numbers will be finalised in March are just wrong,” says one ABC executive. “What we need is some clarity [about long-term resourcing] from the government.”[…]

Receiving Data With Web Based Shortwave Radios (Nuts and Volts)

Your computer and the Internet give you free access to over 100 web based shortwave receivers that you can use as if they were your own. Unfortunately, employing these radios to decode data transmissions can be very difficult or impossible — unless you know the secret. So, read on and we’ll guide you through the details of how to do it.

Web based shortwave radios are an amazing new implementation of software defined radios (SDR). These SDRs are free to use and widely available on the Internet. Even more remarkable is that they are located in countries all around the world.[…]

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Rescuing the Eton E1 from a sticky situation

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I’m back from a week of travels and the 2020 Winter SWL Fest. In short, is was another amazing Fest and so much fun. I hope to write more about it in the coming days, when I have a few moments to catch up and after I shake a nasty bug (chest cold) I picked up.

Although I had no intention of making purchases at the Fest beyond a few raffle tickets, I couldn’t resist snagging an Eton E1 (XM version) at a silent auction from the estate of our recently-departed friend, Tony Pazzola (WB2BEJ). Tim Moody kindly organized the silent auction.

Tony was an amazing friend to all and an avid radio collector, so there were some excellent radios offered up in the silent auction–I could have easily easy bid on each and every one of them! In the end, though, only one really caught my eye: the Eton E1 XM.

A small sampling of the radios from Tony’s estate.

Tony took amazing care of his radios, but his Eton E1 XM suffered from what all of those models eventually do: a sticky chassis.

Back in the day (roughly 2009 to 2013) Eton/Grundig covered a number of their radios models with a rubberized coating that unfortunately breaks down over time and becomes tacky or sticky to the touch.

I think this E1’s sticky coating put off potential bidders.

It was particularly nasty–if you picked up the radio, you had to immediately wash your hands.

The E1’s starting bid on Friday was $200–quite fair considering this unit is fully-functional and comes with all software, cables, manuals and a SiriusXM radio antenna. By Saturday, the starting bid had been decreased to $150. I resisted putting in an offer, but after seeing that it didn’t sell after all bidding had ended, I couldn’t resist. That E1 needed a good home, right? Plus the proceeds go to Tony’s family.

The sticky coating didn’t scare me. If you’ve been an SWLing Post reader for long, you’ve no doubt read our numerous posts about cleaning off this mess. There are a number of solutions, but I’ve heard the most positive long-term results by employing a de-greasing product called Purple Power (click here to read archived posts). Indeed, it’s the solution Eton Corporation recommends.

On the way home Monday, I stopped by a big box store and grabbed a bottle of Purple Power.

Tony still had the original plastic film on the large backlit display.

Sporting a pair of nitrile gloves, I grabbed a bunch of paper towels and a few cotton swabs, then started the cleaning process. I spent the better part of an hour carefully going over the entire body of the E1and trying to remove residue in every crevice without allowing the Purple Power solution to creep under buttons.

In short?  I’m very pleased with the results and am now a solid believer in Purple Power.

As others have reported, Purple Power breaks down the sticky residue and allows it to be removed with a cloth or towels with very little scrubbing. Indeed, the process was much easier than I anticipate.

Now I have a super-clean Eton E1 XM to put on the air!

Now I have no excuse to finally remove the sticky residue from both my Grundig G6 and G3!

So far, I’m loving the Eton E1. It is, no doubt, a benchmark portable. Of course, another motivation behind snagging this E1 is so that I can compare it with the Eton Elite Satellit once it eventually hits the market.

Do you have an Eton E1?  What are your thoughts about this receiver? Please comment!

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Guest Post: Radiofreunde NRW’s DXpedition-grade signal distribution system

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Many thanks to SWLing Post contributor, Joachim von Geisau (DH4JG), for the following guest post:

Signal distribution at SWL camps: The new JK-1000 HF distributor

by Joachim von Geisau (DH4JG)

The Friends of Radio NRW – an independent group of shortwave listeners and radio amateurs in Germany – have been organizing 2-3 SWL camps per year for a number of years, where they meet as far away as possible from electrical noise in order to listen to shortwave together.

To distribute antenna signals, we have previously used an RFT AVV01 antenna distributor.

At an SWL camp there are high demands on signal distribution. Both very weak and strong signals should be distributed well, un-distorted, without noise and other interference. The signal levels are approximately between 0.2 ?V (S1) to over 5 mV (S9 + 40 dB), with a frequency range of at least from 150 kHz to 30 MHz, thus broadcast bands from LW to SW are covered, also all amateur radio bands from 160 m to 10 m.

Popular among listeners are RFT AVV01 RF distributors from the former GDR, at least 30 years old. However, the use of an AVV01 has several disadvantages: high power consumption, difficulties in getting spare parts, high upkeep with corroded contacts and the like. In addition, the transmission of the LW/MW range drops, which is a disadvantage especially for MW listeners. The NV-14 system from Rohde & Schwarz from the late 1960s has the same weaknesses.

Two years ago, the desire arose to develop a concept for the replacement of the RFT system.
The following aspects were important:

  • Frequency range at least 100 kHz – 30 MHz, as linear as possible
  • frequencies below or above desirable
  • Running on 12 V DC or integrated noise-free power supply
  • Remote power supply for active antennas
  • Robust structure
  • Versatility
  • Hobby friendly budget

The amateur radio market offers several products for RF signal distribution (e.g., ELAD, Bonito et al.), but no solution to distribute 6-8 antennas to 10-12 receivers. It was clear from the beginning that DIY development was inevitable.

The starting point of the considerations was to integrate remote power supply for active antennas, an amplifier stage and a distribution network.

Such a distributor is able to distribute an antenna signal to several receivers; several antennas require several such distributors, which led to the decision to implement the project in plug-in technology.

With OM Frank Wornast DD3ZE (www.dd3ze.de), known e.g. for his converters, filters and the like, a well-known RF developer could be won, who took over the implementation of the concept based on the detailed specifications. OM Wornast first produced a prototype without remote power supply, which already did an excellent job of RF signal distribution.

A “hardness test” at an SWL camp showed that this distribution module easily fulfilled our requirements: Frequency range 10 kHz – 50 MHz (also usable with a few dB loss above 50 MHz). Supplemented by a switchable remote power supply and a 90V gas discharger at the antenna socket, the final PCB layout was created, representing the core of the new HF distribution system of Radio Freunde NRW

The distribution block consists of the following components:

  • Input with 90V arrester & 100 kOhm MOX resistor to dissipate static interference
  • Remote power supply, switchable, 10-14 V, max. 350 mA
  • Amplifier stage with 14-14.5 dB
  • Resistor network for distribution

The device is characterized by a very smooth frequency response and has a very low inherent noise. It offers the possibility of using levels of -120dBm with very good SNR
to process up to strong levels of up to + 14dBm. In addition, the reception on VLF is now possible, which did not work with the previous system.

 

The PCB is designed in a very practical way: series resistors for LEDs are integrated as well as fixing points for coaxial cables. The remote power supply can be switched separately, but can also be used permanently by means of a jumper.

With this concept, the distribution block can be used universally: use on an active or passive antenna with distribution to several receivers, by means of a step switch in front of it also for several antennas; if you leave the remote feed path unconnected, the block can also be used as a simple distributor, so it is almost universal for hobby purposes.

For use on SWL camps, we decided to install them in 19 “rack-mount technology. A standard rack can thus accommodate 4 distributors and a power supply, allowing  distribution of 4 antennas to 12 outputs each. An example of the installation is shown in the following picture: Parallel to the input is another BNC socket, which is connected via a C 100 nF where the input signal can be used DC-free for measurement purposes or the like. The distribution unit is installed in a transport case. The components themselves are mounted in slide-in housings which are provided with a corresponding front panel: Such front panels might be obtained from CNC manufacturers.

On the back + 12V DC must be supplied as operating voltage. For the power supply units, we opted for linear power supplies because we have made the best experience with these without interference. For a distribution unit with 4 slots, a power supply with 12V 1A is sufficient – each distribution block takes about 55 mA, an active antenna up to 150 mA, so even with “full load” a power supply with 1 A is sufficient. The distributor was tested with various well-known active and passive antennas, including a PA0RDT MiniWhip, active loops, long wires and T2FD.

Due to the wide input voltage range, the module can handle nearly any antenna. The cost for a distributor for 4 antennas amounts  (depending on the version: housing, sockets, switches, power supply, etc.) to about 700-1000 €. That may seem a lot at first glance. However, taking into account that a simple 5-gang distributor from mass production costs already around 250 ¬, the cost of the distribution of 4 antennas to each up to 12 outputs are not that much. The Friends of Radio NRW use two of these distribution units for SWL camps.

If you are interested in building one, please contact the author ([email protected]) for further information. The development history of the distribution unit is also available at www.dx-unlimited.eu.

Wow!  What a beautifully engineered antenna distribution solution, Joachim!  I love how you worked together to sort out all of the requirements for your system then build it for ultimate performance and flexibility.  No doubt, you and your colleagues at  Radiofreunde NRW posses a lot of design and engineering skills!  Simply amazing and thank you for sharing your design with the radio community!

Contact Joachim for more details and check out notes and discussion at www.dx-unlimited.eu (may require registration).

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Mike Ladd’s primer on decoding NAVTEX using an SDRplay SDR with SDRuno

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Many thanks to SWLing Post contributor, Mike Ladd with SDRplay, who shares the following PDF primer on decoding NAVTEX with an RSP series SDR.

Click here to download “Basics to decoding NAVTEX using an RSP and SDRuno” (PDF).

Thanks for sharing this excellent guide, Mike.  Without a doubt, SDRplay has some of the best documentation and primers in the world of radio. Click here to check out more.

Also, check out Mario’s post, from our archives, which discusses decoding NAVTEX, RTTY, and Sitor B.

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DRM30 on a Smartphone: KTWR Shows Us The Way

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Image via the KTWR Blog

Many thanks to SWLing Post contributor, Dan Van Hoy, who writes:

[Regarding the reception of DRM via smart phone,] I happened to find this KTWR Guam post about decoding DRM30 with a smart phone, app, and an RTL-SDR:

Convert Smart Phone to DRM 30 HF receiver!

We are pleased to report successful use of an SDR Dongle used to directly receive and Decode DRM 30 over HF today.

The SDR Dongle is an RTLSDR v3 type connected to an android smartphone using an OTG cable (phone or tablet must be OTG capable).

The Software used:
1. Android driver (free)
2. DRM+SDR Android App ($4.99)

The Frequency of the HF broadcast is directly assigned within the DRM+ SDR app with two settings
1. Frequency in Hertz
2. RF Gain (0-512)

Demonstration video showing Clean DRM decode of AAC Audio and Journaline data along with live metadata.  (our signal was very strong, so only a short wire used for Antenna, DX’rs will need an appropriate Antenna)

Now anyone with a smartphone and a $20 SDR can receive DRM 30 HF broadcasts…

Click here to read this post on the KTWR blog.

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Restoration of a USN version of the ARC-5 command set receiver

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(Source: Southgate ARC)

Gregory Charvat N8ZRY writes on Hackaday about an un-modified-since-WW2 surplus CBY-46104 receiver with dynamotor.

He writes:

I’ve been told all my life about old-timey Army/Navy surplus stores where you could buy buckets of FT-243 crystals, radio gear, gas masks, and even a Jeep boxed-up in a big wooden crate. Sadly this is no longer the case.

Today surplus stores only have contemporary Chinese-made boots, camping gear, and flashlights. They are bitterly disappointing except for one surplus store that I found while on vacation in the Adirondacks: Patriot of Lake George.

Read the full story at
https://hackaday.com/2019/12/12/wwii-aircraft-radio-roars-to-life-what-it-takes-to-restore-a-piece-of-history/

Video

Video description: Repair and restoration of a USN version of an ARC-5 command set receiver. This model covers 1.5-3 Mc, runs off its original dynamotor, with no internal circuit modifications. This radio is original with the exception of a small number of caps that tested bad which were re-stuffed. Build date is Feb. 42, who knows where and what this radio may have been involved in?

I’ve always wanted a functioning ARC-5 command set to accompany my BC-348-Q receiver. This article has inspired me.

Post readers: Anyone own a functioning ARC-5 (or any variants)? Please comment!

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