Category Archives: Guest Posts

Guest Post: Switching a Remote Antenna, Low Noise Amplifier, and an Antenna and Audio Between Two Radios

Many thanks to SWLing Post contributor, Bill Hemphill, who shares the following guest post:

Remote Antenna Switching Remote Low Noise Amplifier Switching and Switching an Antenna and Audio Between Two Radios

by Bill Hemphill, WD9EQD

Remote Antenna Switching

I have two YouLoop Antennas. I had been placing them at right angles to each other. I would then put one of them on the AirSpy software defined radio. But manually switching from one antenna to the other was a real pain. If only there were a way to electrically switch between the two antennas.

It would be nice to place the antennas remotely from the radio (and computers) and then have some sort of remote switch that would select an antenna and then a single feed line to the radio. It was research time.

The YouLoop and the Airspy both use SMA connectors. An SMA switch would be required. A little research and I came across the following small board that can switch between two SMA antennas:

From Amazon Description: 50 Ohms RF Switch Module, 3-5V Remote Wireless RF Switch Single Pole Double Throw Board Input Output Impedance for DIY Electric Doors (HMC349)

This board is perfect for RECEIVE only projects. Apply 5V to the board and then 5V to the VCC (control pin) to switch from RF1 to RF2.

Now that I had the SMA switch module, a way to actually do the switch remotely was required. Maybe WI-Fi or Bluetooth module would do the trick. I found a nice Wi-Fi module on Amazon that looked like it would do the trick:

Amazon Description: DIYmalls SV Safe Low Voltage WiFi Wireless Switch Module DC 5V-24V Phone APP Remote Control Smart Home for Amazon Alexa Google Assistant

But do I really want to use a phone app to switch antennas. Further investigation discovered a really neat module that uses a Car Fob type control:

Amazon Description: RODOT Mini Relay Wireless Switch, 433Mhz Remote Control Relay Switch, DC 6V 12V 24V 1CH Channel Relay Wireless Secure RF Transmitter and Receiver kit, Momentary Toggle Latched Mode

BIngo!! I could just press a button and switch antennas. But a problem quickly arose. I hadn’t fully read the description of the RODOT switch:

The blue output wire is ALWAYS Vcc (input voltage)! The device only switches the ground.

So the RODOT switches the ground but the HMC349 uses positive voltage to switch. OOPS. Next step was to place a latching relay to take the on/off ground and convert it to on/off positive. Again, another nice board was found:

Amazon Description: HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger

The nice thing about the Relay Module is that it can be latched either High or Low, so the RODOT switching ground can be used to latch the relay and then provide a positive voltage to the HMC349 antenna switch.

All modules are powered by 5V. There are other modules available that use higher voltages. But I wanted to be able to use a 5V power source for everything.

I learned a quick lesson on the first layout I did. I had directly connected the antenna cables to the HMC349 module. A quick accidental side yank on one of the antenna cables and the SMA connector tore off the board. A replacement board and some quick wiring and I had a workable antenna switch that with the press of the car fob button, either antenna could be selected.

I found a nice small plastic box that allowed for the HMC349 module to be suspended between SMA bulkhead connectors. By using bulkhead connectors, there is no strain placed on the HMC349 connectors. The relay module was attached to the box lid. The modules are mounted using brass standoffs. The finished box is about 3”x4”x 2” high. Either battery or a 5V wall module can be used to power it.

Overall, I’m quite pleased with the results. I find that sometimes switching antennas (and their orientation) can make a big improvement in the signals. Other times, there’s very little difference.

Remote Low Noise Amplifier along with Antenna Switching

Now that the antennas can be switched, it would be nice if a Low Noise Amplifier could be switched in and out of the circuit. Something like the Lana HF Barebones LNA made by NooElec:

For testing purposes, I first did a quick layout of just using one antenna with the ability to switch the LNA in and out. Note: I took a gamble on hooking the antenna cables directly to the HMC349 modules. Luckily, the SMA connects didn’t tear off the boards.

Two HMC349 modules are used. The first module selects the bypass or the LNA. Likewise, the second module also selects either the bypass or LNA. Note that the second module is turned upside down so that the switches match up when activated. Two modules were used so that the LNA is totally switched out of the circuit. Continue reading →

Spread the radio love

Around the world, around the world

Don Moore’s Photo Album: Costa Rica (Part One)

3 Replies

Radio Reloj, Costa Rica (1990)

Many thanks to SWLing Post contributor, Don Moore–noted author, traveler, and DXer–for the latest installment of his Photo Album guest post series:

Don Moore’s Photo Album: Costa Rica (part one)

by Don Moore

Costa Rica is one of the most visited countries in Latin America. I only visited there once, for three weeks in May-June 1990 when the country was just beginning to become a major international eco-tourism destination. Visitors were few and prices very affordable. Except for a short trip to the Monteverde cloud forest, we spent all our time in the central valley, staying in San José and nearby Heredia. Rather than nature, our visit focused on cultural and historical sites … and a lot of radio stations.

Since the 19th century, Costa Rica has been one of the most literate and educated countries in Latin America. That quality is reflected in its radio broadcasting industry, which has always been very professional. Curiously that’s even reflected in station verifications. Almost every Costa Rican shortwave station that I’ve verified had a professionally printed QSL card.

Despite being one of the smallest countries in Latin America, Costa Rica had a lot of shortwave radio stations. I have fifteen in my logbooks and some of the most famous ones were already off the air when I started DXing. Unfortunately, shortwave broadcasting from Costa Rica ended almost twenty years ago so there’s no more to be had. It is still possible to log Costa Rica on medium wave but it’s not as easy as it once was. When I started DXing in the early 1970s, stations in the San José were spaced twenty-five kilohertz apart. That meant that every other station, such as Radio Sonora on 675 kHz and Radio Columbia on 725 kHz, was on a split frequency that fell between the normally assigned 10 kHz channels. I logged nine Tico stations on medium wave while DXing from Pennsylvania in 1972-1981 and only one of those, Radio Reloj on 700 kHz, was on an even channel. Those split channels were eliminated in the 1980s so logging Costa Rica on medium wave is no longer a slam-dunk.

I visited a lot of radio stations and took a lot of photos on my one long-ago trip to Costa Rica. I’m going to focus on just five shortwave broadcasters in this first look at Costa Rica. The others will be featured in two or three future columns.

In the 1970s the first Costa Rican station most shortwave DXers heard was Faro del Caribe, or Lighthouse of the Caribbean. This religious station used two kilowatts on 9645 and 6175 kHz and got out surprisingly well as long as there wasn’t a more powerful international broadcaster also using the same frequency. In the late 1970s they added 5055 kHz in the sixty-meter band.

When I visited in 1990 the antennas were located right next to the studio building. The site was outside the city of San José when the station was founded but gradually a residential area built up around it.

Engineer checking one of Faro Del Caribe’s shortwave transmitters.

Fortieth Anniversary pennant from 1988. When Faro del Caribe began broadcasting on February 23, 1948, it was the first Evangelical Protestant radio station in Central America.

For DXers, Radio Reloj was one of Costa Rica’s best known radio voices for several decades. The station was founded as Radio Cristal by Roger Barahona in 1945. The shortwave frequency of 6006 kHz was added in the early 1950s. In 1958 the station was renamed to Radio Reloj when the format changed to focus on news and community announcements with very frequent time checks. (Radio Reloj means Radio Clock.) Roger’s brothers Isaac and Francisco had joined the broadcasting company and Radio Reloj was assigned the callsign TIHB for Hermanos Barahona (Barahona Brothers). Continue reading →

Spread the radio love

Remember the good olde days with a lovely cup of tea

2 Replies

Hi to all of the SWLing community, Fastradioburst23 here with news about Imaginary Stations on the shortwaves this Sunday 20th August 2023. The first show will be beamed to Europe via the services of Shortwave Gold in Germany at 2000 utc on 6160 khz and will feature another transmission of WREN, this time it’s music of a Renaissance style, so turn back the hands of time to ye days of olde and tune in. You will get more out of the broadcast if you have a lute, recorder or a harpsichord handy.

Then later at 2200 hrs UTC on 9395 kHz via WRMI we bring you the debut of WTBR, your only official tea and biscuits radio show. There will an assortment of plain and fancy tunes and all the tea you can drink so make yourself (a tea) cosy and enjoy a nice relaxing time via the shortwaves. Even the Ionosphere will enjoy a little tea break to recharge its batteries.

For more information on the shows please email [email protected] and check out our old shows here. Here’s the trailer for the show.

Spread the radio love

Guest Post: A review of the Chaoyuan LC90 Hybrid Shortwave/4G/Internet Radio

28 Replies

Many thanks to SWLing Post contributor, Michael Ye (BD4AAQ), for the following guest post:

The LC90, a Great Radio Spanning Two Worlds

by Michael Ye (BD4AAQ)

It is an awkward era for radio receivers. Although technology becomes more and more advanced and increasingly sophisticated radios are made, there are fewer and fewer stations to listen to. But hardcore radio hobbyists, mostly hams and shortwave listeners, would not give up the hobby. They continue to look for and enjoy stations among noises in the airwaves. Although Internet radios have been around for a long time, I never thought seriously about them. Perhaps I was stubborn, but in my mind, radios were noises and noises were radios and it’s the stations among the noises that I enjoyed. Receivers without noises were hardly real radios.

Until I got my first full band radio with Internet features. The LC90 was a pleasant surprise, completely changing the way I look at radio receivers. The LC90, or “full band smart Internet radio”, is my first shortwave radio AND Internet radio in one. There may be other radios with Internet features, but I have heard of few receivers that integrate the traditional radio (shortwave in particular) and the Internet. The LC90 was launched in China in early 2023, and quickly became popular among hobbyists thanks to the unique combination. News has been confirmed that the overseas version of the LC90 will be launched later this year. It provides more options for users at a time when shortwave broadcasters continue to shut down transmitters and bid final farewell.

Chaoyuan Company

The manufacturer of the LC90 is Chaoyuan, an electronics company based in Shenzhen, China, known for mobile phone design and Hi-Fi equipment. In recent years they started to design and make radios. And they are serious about the business, too.

The LC90 full band smart Internet radio

The Radio at a Glance

The radio is of regular size. A computer mouse is placed in the picture above, so you have an idea of not only the radio’s looks but also its size. The exact dimensions are 200x122x40mm. Its weight is 640 grams. The radio has a built in 4G SIM card, with 3G prepaid data. You have to add credit to the card in time by scanning a QR code on the screen before the built-in SIM card expires. You can also use your own SIM card by inserting it to a slot at the bottom of the radio. And of course, you could use Wi-Fi at home.

Although the radio is a combination of the traditional radio and the Internet, it is very ingeniously designed and does not put off the user with too many bells and whistles – you could press the tuning button to change the shortwave band and the fine tuning button to change the band width. The tuning button also serves as an “enter” key. These are clever designs that effectively save extra buttons. I have not seen a similar design in other radios.

For those who do not read Chinese, the upper five buttons are, roughly, “Configure”, “Timer”, “Setup”, “History” and “Favorites”. The four buttons on the left: “Confirm”, “Stations”, “News” and “Menu”. The four buttons on the right: “Back”, “Sequence”, “Rewind” and “Fast Forward”. The button with a globe says “Internet”.

The radio has excellent audio quality, rich bass, with a well-balanced frequency response. It is powered by two 18650 rechargeable lithium batteries. The radio has no back stand.

Traditional Radio

All three modes (or bands) are available, FM, MW and SW, as shown in the three buttons on the upper right (to get LW just press MW again). The FM band covers 64-108MHz, which includes Japan’s FM band. During the FMDX season you could have stations from Japan and other countries to explore. The SW band covers 2300-26100KHz, continuous, almost the entire shortwave band, more than enough for broadcast listening. The antenna jack works for all three modes (or bands).

Excellent Shortwave Performance

As a shortwave listener of many years, I am most interested in the radio’s performance in shortwave reception. Well, it is indeed very good in terms of sensitivity, selectivity and audio quality, with no compromise although the radio has an Internet section which requires additional space and resources.

When you use the radio indoor, reception could be poor and you can insert an external antenna to the antenna jack. Unfortunately, I cannot connect my AOR LA400 loop antenna to it as the antenna jack is too close to the tuning knob and so there is not sufficient space for the plug (see picture). Generally, a 3.5mm plug with a wire should work well if you extend the wire outside.

The external antenna jack

If there is a disappointment, its shortwave reception does not decode SSB signals. If the user is not a ham radio hobbyist, SSB reception may not be really needed anyway and the buttons, circuits and space can be saved accordingly.

Fair FM Reception

FM reception is good, but there is no obvious improvement of reception when an external plug is inserted in the antenna jack.

Mediocre MW Work

Reception on the lower bands, e.g., the medium wave band, is always a challenge in cities. It is not surprising that medium wave performance of the LC90 is mediocre at best. I don’t do much MW DXing but nowadays for each MW frequency there is almost always an FM frequency. Let’s face it – we should perhaps forget about medium wave reception in cities where there is excessive low band EMI.

However, if you go outdoor with the radio, medium wave reception can still be a lot of fun. And, contrary to FM reception, an external antenna significantly improves its performance!

Internet Radio

Admit it or not, the best days of traditional radio are gone, and while we continue to have fun on the old time radio, we should not hesitate to embrace newer technologies such as the Internet. By launching the LC90 and combining the two, Chaoyuan has made a significant move.

The Internet radio is an integrator of many online stations on the Internet, and more. It is completely different from the traditional radio which receives radio signals transmitted on air. The Internet radio, which relies on the Internet, provides much better audio quality, no noise, customizable and replay-able.

If you want to kill time and look for signals from noises, turn to shortwave and enjoy DXing. If you feel like listening to solid content or enjoying noise-free music, the Internet radio is there for you. This Internet radio integrates major web stations in China and on that basis the user can further select and configure their own favorites. Among apps that are built-in is Ximalaya FM, the leading audio platform in China. Due to requirements of policies and regulations in China, the user does not have much discretion to include foreign stations in the radio. However, Chaoyuan has indicated that they are working in an effort to secure authorizations from Spotify, Alexa and Pandora which they hope could be incorporated in the overseas version of the LC90. The future overseas version is expected to give the user more discretion to include online stations of their own choice.

A closer look at the display of the Internet Radio

Two buttons, Ai1 and Ai2, are voice assistants. Activate and speak to them and the radio directly plays the content (Ai1) or displays their findings for you to choose from (Ai2).

Finally, this is a radio with the most accurate time. There is no need to set the time for it, as it is based on the Internet.

Spread the radio love