Monthly Archives: January 2019

Dave’s review of the Sangean DAR-101 digital recorder

Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who notes that he has updated his Sangean DAR-101 recorder:

Yes, a newly tested (latest production) sample of the [DAR-101]. My years old “lightly used” sample died back in the fall. New one seems to work less sluggish with the updated firmware as well as adding monitor speaker selection in the menu’s.

http://n9ewo.angelfire.com/dar101.html

The AC Adapter info should also be valid for the ATS-909X as well.

Nice standalone MP3 recorder with a built in amplifier and large speaker.

Thanks, Dave.  This is a very tempting purchase. I do quite a lot of off-air recordings for the SWLing Post and, especially, the Shortwave Radio Audio Archive. I typically use my Zoom H2N for line-in recordings, but at home would prefer something that would sit on my desktop better and with a built-in speaker. The DAR-101 might fit the bill.

I see that it’s currently $81.52 on Amazon right now (affiliate link) and $99.95 at Universal Radio.

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Radio receiver innovations over the last century

(Source: Microwaves and RF)

A Selected History of Receiver Innovations Over the Last 100 Years

by Brad Brannon

This article, the first of a two-part series on receiver technology, looks at the genesis and early advances of this all-important area.

Many contributed to the early days of wireless, but it’s safe to say that Guglielmo Marconi ranks as one of the more prominent. While known for his wireless technology, many people are less familiar with the business he created around wireless technology at the turn of the 19th century. For about 20 years after the start of the 1900s, he built a critical business that launched the world of wireless toward what we have today.

His commercialized technology was not the most up-to-date.  However, it was good enough despite rapid technological changes because he figured out how to use the technology available to him to enable a new industry.

Marconi set out to deploy a worldwide network capable of sending and relaying messages wirelessly at a time when the world was in turmoil at the end of colonialism, mainly due to the wars and disasters that pockmarked the start of the 1900s, including the sinking of the RMS Titanic in April of 1912. The role that wireless played in both the rescue of survivors and the dissemination of the news of that accident reinforced the importance of this fledgling technology.

The key role that wireless technology could play wasn’t missed by either the public or the military, notably Joseph Daniels, who later became the secretary of the U.S. Navy. In the U.S. and elsewhere, leaders such as Daniels felt that the military should nationalize radio to ensure that they had access to it during wartime. It must be kept in mind that during this period, the only usable spectrum was below 200 kHz or so. At least for a while, things moved in this direction. After World War I, the government’s control of wireless weakened, but not before the formation of the government-sanctioned monopoly that created the Radio Corporation of America (RCA).1

The Early Radio Days

By our expectations, the radios of Marconi’s time were quite primitive. The transmitters employed spark-gap devices (only later did they employ mechanical alternators) to generate the RF. But on the receiving end, the systems were fully passive and consisted of an antenna, resonant LC tuner, and some sort of detector. These detectors will be covered shortly, but they were either mechanical, chemical, or organic.

Some of these systems employed a battery simply to bias them, but not to provide any circuit gain as we might recognize today. The output from these systems was supplied to some sort of headset to convert the signal to audio, which was always very weak and just a simple click or buzz at best.

Because these systems provided no gain on the receiving end, range was determined by the amount of transmitted power, the quality of the receiver, the experience of the operator to adjust it, and, of course, atmospheric conditions. What Marconi realized was that given a reasonably predictable range, a network of stations could be built to reliably communicate information across both continents and oceans. This included installations both on land and at sea.

Marconi set off to install his wireless stations across the globe and at sea, both on passenger ships and cargo ships.[…]

Click here to continue reading the full article at Microwaves and RF.

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Radiwow offers deep discounts for R-108 unbiased reviews

Many thanks to SWLing Post contributor, The Professor, who notes that Radiwow is offering free and half-price units to consumers willing to review their R-108 receiver. All of the details are on the Radiwow R-108 product page at AliExpress.

Here’s a copy of the statement:

Dear friends

Are you still struggling to find a cost-effective radio? Now the FREE  opportunity is coming!

Recently ,our store have launched a RADIWOW® R-108 Radio which has  great sound quality, selectivity and sensitivity .R-108 Radio is a good world receiver with great FM Stereo/LW/SW/MW /AIR/DSP. It will start selling on January 30, 2019.You deserve it!

We are looking for 20 people from Japan, the United States, Canada, the United Kingdom, Germany, Spain, Italy, France to test and write an unbiased and honest review for our latest radio.

In addition, we need friends from Spain, Italy, France to help us translate R-108 English user manual into Spanish, Italian and French.

In all top three users who apply for the test will enjoy the radio for free, and the 3-20 will enjoy it at half price. Please indicate in the subject when contacting us: your country; product model; leave review or translate user manual.

Click here to read this statement on the Radiwow R-108 product page.

Please comment if you’ve successfully ordered a unit under this program. I’m currently evaluating the R-108 here at SWLing Post HQ.


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Tivdio V-115: Simple modification to abate internally-generated noise

Many thanks to SWLing Post contributor, Marc Thomas, who shares a link to this site which describes modifications to eliminate the Tivdio V-115’s internal noise.

In a nutshell, the author made two small mods:

  • Decouple the power/battery with an electrolytic capacitor of around 10uF soldered to the battery connector inside the radio (see photo above)
  • The author also grounded the speaker, but didn’t test to see if this alone had any positive impact

I could not find contact details for the author of this mod, so I hope they don’t mind the fact I shared it here on the SWLing Post.

Note that the Tivdio V-115 is also known as the Audiomax SRW-710S and Kaimeda SRW-710S (and likely rebadged as a number of other models).

Click here to read reviews of this radio.

Retailers:

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Bedside radio: Jeff ousts the Sangean WR-2 in favor of the Grundig G4000A

(Source: The Herculodge)

Our friend, Jeff McMahon, over at the Herculodge blog has just replaced his bedside radio–he writes:

Inexplicably, the Sangean WR-2 wasn’t getting 89.3 KPCC without static, distortion, and bleed-in from another station, over the last few weeks, even with the wire FM antenna attached to the back of it. Who knows why FM reception is subject to variation. It could be the weather.

In any event, I put the Sangean WR-2 in my daughter’s room (she gets her pop station MyFM 104.3 very easily, with the pigtail antenna on the back) and put the 13-year-old Grundig G4000A by my bedside. With the telescopic FM antenna alone, KPCC has a weak signal, evidenced by the Grundig’s reception meter, but when I put the wire SW antenna to the side SW antenna port, the reception is strong and clear.

Over the years, I’ve had many portables, including the Degen 1103, and some old Tecsun models from about 10 years ago. They all suffered from weak tin speakers. Not so with the Grundig G4000A. The speaker sound is very pleasing.[…]

Continue reading at the Herculodge.

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Building a Raspberry Pi magnetometer network

Source: Ciarán D. Beggan and Steve R. Marple

(Source: Southgate ARC)

Ciarán Beggan of the British Geological Survey describes how a network of 9 Raspberry Pi magnetometers were deployed to schools around the UK to measure geomagnetic storms

As computers such as the Raspberry Pi and geophysical sensors have become smaller and cheaper it is now possible to build a reasonably sensitive system which can detect and record the changes of the magnetic field caused by the Northern Lights (aurora).

Though not as accurate as a scientific level instrument, the Raspberry Pi magnetometer costs around 1/100th the price (about £180 at 2019 prices) for around 1/100th the accuracy (~1.5 nanoTesla). However, this is sufficient to make interesting scientific measurements.

During 2017, a network of 9 Raspberry Pi magnetometers were deployed to schools around the UK from Benbecula to Norwich. On September 8, 2017 a large geomagnetic storm was captured by the school magnetometers. Using these data and the array of other magnetometers around the North Sea, we were able to recreate the spatial and temporal changes of the magnetic field during the storm in great detail. The two phases of the storm show the westward (night time) and eastward (daytime) flow of the auroral electrojet currents in the ionosphere.

Source http://www.mist.ac.uk/nuggets

Download the paper Building a Raspberry Pi school magnetometer network in the UK
https://www.geosci-commun.net/1/25/2018/gc-1-25-2018.pdf

Click here to read at the Southgate ARC.

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WRTH 2019: Now at Book Depository

Many thanks to SWLing Post contributor, Richard Langley, who writes:

WRTH 2019 is finally available from Book Depository — quite a bit later than last year.[…]

It’s up on their website today at $32.59 U.S. (26% off) with free shipping:

https://www.bookdepository.com/World-Radio-TV-Handbook-2019/9781999830014

Thanks for the tip, Richard! Book Depository is a great source. You can also check pricing at the publisher’ site, or from a distributor like Universal Radio (US), and Amazon.com (US). Book Depository’s price is hard to beat, though, especially for those living outside the US.

Click here to read our review of WRTH 2019.

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