Category Archives: Shortwave Radio

Details Emerge: The PantronX Titus II DRM Portable Receiver

TitusII-DRM-Receiver

Many thanks to SWLing Post contributor, Harald Kuhl (DL1ABJ), who shares more details about the new Titus 2 DRM receiver via the DRM Consortium Chairman, Ruxandra Obreja:

NEW DRM RECEIVER UNVEILED at HFCC MEETING IN MIAMI, FLORIDA THIS WEEK!

The HFCC meeting is being held 22-26 August in Miami and on this occasion there was a live DRM transmission form Radio Vaticana received on  the new Titus2 DRM receiver (pls. see attached document with picture and details) http://www.drmna.info/.

Here is also a little testimony of how this prototype to be sold “at under 100 dollars” performed from Ray Robinson, Operations Manager at KVOH (Voice of Hope / Voz de Esperanza):

I’m currently at the HFCC conference in Miami, and reception of the DRM broadcast here this afternoon was very successful.  Reception was made outside the hotel on two receivers – a  NewStar DR-111 and a brand new pre-production receiver from Pantronix called the Titus 2, with a cluster of attendees gathered round taking photos and videos.  The latter receiver is based on an Android tablet in a stereo radio format with one speaker each side of the central horizontal tablet.  Reception on both radios was solid throughout, on a day when analog reception on 16m was plagued with a lot of atmospheric noise.  We haven’t done detailed calculations, but figure there were probably at least three hops from Italy to Miami, and for a daylight path, the reception quality was nothing short of astounding.

Click here to download the Titus II PDF brochure.

TitusII-DRM-Receiver-Specifications

The PantronX Titus II: A New DRM Receiver

titus 2 big

I had heard rumors that a new DRM receiver was in the works, but had not yet seen any specifications. DRMNA.info has just posted a few specs:

The PantronX Titus II is actually a full SDR solution in a boombox case. Few details yet, but it is running Android, has a 100 kHz to 2 GHz receiver on-board and decodes AM, FM, SSB and DRM natively.

It uses a Quad-core Arm A53 @ 1.2 GHz, 1 Gig of RAM and 8 Gig of on-board Flash. 7″ TFT display and supports Android 5, 6 or custom remixes.

Click here to read the full post at DRMNA.info…

Guest Post: A WRNO Worldwide Transmitter Site Visit

Many thanks to SWLing Post contributor, Dan Brown (W1DAN) for the following guest post:


A WRNO Worldwide Transmitter Site Visit

by Dan Brown W1DAN

WRNO-logo

The opportunity to visit a shortwave transmitter site does not come to me often. It did during the summer of 2009, so I jumped at the chance. Along with friend Bob K5IQ, we visited the WRNO Worldwide transmitter in New Orleans and were guests of Chief Engineer Larry Thom. He kindly showed us the transmitter site, talked of the interesting technical story of the rebirth of the WRNO Worldwide transmitter site and displayed some of his ingenious technical adaptations to create a smooth running plant.

Fullscreen capture 8222016 40935 PM

Larry smiles as Bob Is amazed at the innards of the WRNO HF transmitter!

Originally put on the air as the first commercial shortwave station by local New Orleans radio owner Joe Costello in 1982, and purchased by Dr. Robert Mawire of Good News Outreach in 2001, the now non-profit religious station is fed from Fort Worth Texas studios. The transmitter, still in the New Orleans suburb of Marrero, primarily operates at 7505KHz and can be heard evenings from 1200 to 1400UTC (8PM to 10PM EST).

The plant’s main feature is an Electronic Corporation (Elcor) SW50/3S fifty kilowatt transmitter (see Figure 1). Built in Costa Rica, this transmitter feeds a TCI 516-3 log periodic antenna that was a mainstay of the Joe Costello rock and roll days of WRNO Worldwide. The transmitter is plate modulated and uses time-tested circuitry such as vacuum tubes, relay control and crystal oscillators as compared to solid-state modulators and microprocessor control. The system sends effectively a 3 megawatt signal around the world.

Figure 1. Larry describes the Elcor transmitter. In the foreground is the control cabinet with the control relays out front for easy access.

Figure 1. Larry describes the Elcor transmitter. In the foreground is the control cabinet with the control relays out front for easy access.

Interestingly, Larry incorporates baking thermometers to measure the exhaust air temperature. Cheap and efficient! In order to get the transmitter to work properly two interesting adaptations were required. The first was the transformation of the output impedance from 50 ohms to 75 ohms.  This was done using a custom Elcor transformer as shown in Figure 2.

 

Figure 2. Elcor custom RF transformer

Figure 2. Elcor custom RF transformer

This impedance transformer feeds a TCI high power BALUN (BALanced to UNbalanced transformer, but here run in reverse), as the TCI antenna requires a balanced feed. The BALUN is a commercial TCI unit and is shown in Figure 3.

Figure 3. TCI BALUN takes unbalanced RF from transmitter and feeds the 300 ohm balanced TCI Antenna. How big is your BALUN?

Figure 3. TCI BALUN takes unbalanced RF from transmitter and feeds the 300 ohm balanced TCI Antenna. How big is your BALUN?

Another interesting adaptation became necessary, as the transmitter would often trip the main breaker when it was placed on the air. This problem was due to the high inrush current that would occur when the high voltage power supply was energized. Larry went to Grainger supply and bought high power heating elements and time delay relay. He inserted this in the primary three-phase feed to the power supply. Now, when the supply is switched on, the heating element provides a series resistance (and heats up for a moment) to absorb the inrush. After a short time, the relay would jump the element out to allow full current to feed to power supply (see figure 4).

Figure 4. Heating elements on the upper right inside wall of the power supply limit inrush current.

Figure 4. Heating elements on the upper right inside wall of the power supply limit inrush current.

Another small problem with the transmitter was the drift of the master oscillator. Larry had Elcor build a synthesized oscillator for the transmitter to reduce the drift (figure 5).

Figure 5. Larry with new synthesized reference oscillator module

Figure 5. Larry with new synthesized reference oscillator module

WWL-AM has their 50Kw transmitter on 870KHz near the WRNO Worldwide transmitter. Due to this proximity they send a hefty signal into the WRNO antenna and thus into the transmitter. Here these two signals can mix together to form a soup of audio in the WRNO transmitter tank circuit. A notch filter was constructed to reduce WWL-870’s AM signal (Figure 6).

Figure 6. WWL 870KHz notch filter

Figure 6. WWL 870KHz notch filter

During the visit, Bob and I listened to Larry’s stories and snooped around the building. We spotted a Vintage Radio Labs “Globe King” 500A that is slated as an emergency backup transmitter (Figure 7). It is rumored that this classic redesign of an older transmitter marketed in the 1990’s was a poor copy of the original 1950’s era World Radio Labs Globe King transmitter. Larry states that this transmitter is serial number 1. Only a few were built.

Figure 7. A Vintage Radio Labs “Globe King 500A” backup transmitter (SN1?). The crystal is for the old frequency of 7355 kHz

Figure 7. A Vintage Radio Labs “Globe King 500A” backup transmitter (SN1?). The crystal is for the old frequency of 7355 kHz

Figure 8. Bob K5IQ dreams of calling “CQ DX!” on a 50Kw rig and a 14db antenna

Figure 8. Bob K5IQ dreams of calling “CQ DX!” on a 50Kw rig and a 14db antenna

Figure 9. The Official FCC-approved Reader’s Digest reference modulation monitor!

Figure 9. The Official FCC-approved Reader’s Digest reference modulation monitor!

Figure 10. The audio and control rack. Audio is fed via a T1 line from Texas to the Telos ISDN decoder, then to the Optimod 9000A audio processor (an original from the Joe Costello days). The remote control is a Burk unit that allows the studio folks in Texas to control the transmitter.

Figure 10. The audio and control rack. Audio is fed via a T1 line from Texas to the Telos ISDN decoder, then to the Optimod 9000A audio processor (an original from the Joe Costello days). The remote control is a Burk unit that allows the studio folks in Texas to control the transmitter.

Figure 11. The Marrero, LA transmitter shack heard ‘round the world!

Figure 11. The Marrero, LA transmitter shack heard ‘round the world!

An article I wrote on the re-birth of WRNO Worldwide for the August 2007 Monitoring Times magazine, and the fact that I was on vacation in New Orleans prompted this visit. It is always fun to visit a transmitter site to see how things are done. Thanks to Bob K5IQ for driving!

WRNO-Feedline WRNO-Feedline-B

Figure 12. View from the balanced feed point of the TCI 516-3 log periodic antenna 1ith 14db gain aimed at 20 degrees

Figure 12. View from the balanced feed point of the TCI 516-3 log periodic antenna 1ith 14db gain aimed at 20 degrees

Here are a few web-links of interest:

Copyright
Dan Brown, W1DAN
Created 09/2009
Updated 07/2016


Wow–many thanks for sharing your tour of WRNO with us, Dan! My-oh-my how I’d love to have that 14db gain log periodic at my disposal! Great facility!

Creating a global network of inexpensive remote SDRs

U_Twente_SDR

Many thanks to SWLing Post contributor, Mark Fahey, who replies to Ivan’s preliminary review of the V3 RTL-SDR dongle:

With Shortwave SDRs (the receiver dongle) now costing less than $20, the time has come for us to set up a global group of receivers that we can all log into at will!

RTL-SDR-RTL2832U-e1471375714199Have a look at SDR.hu – here you can put your SDR dongle on line and share it with anyone and they have full control of the receiver just as if it was in their own shack.

Imagine receivers scatted around the world – South America, Tropical Asia, Africa! The cost is now virtually nothing, all that is needed is the dongle, antenna (doesn’t have to be anything special – even a long wire or whip) and a small low cost CPU (Raspberry Pi for example).

Anyone else interested in this dream? Lets get together, get some receivers setup and then talk about our experience in a kick-ass presentation at the 2017 SWL WinterFest in PA!

Also… I am very soon to receive my KiwiSDR matched to a BeagleBone CPU. It will be online at SDR.hu and four remote listeners will be able to tune the full shortwave bands independently, its like my own Twente setup! Heaps of others are getting receivers online in the next few months with KiwiSDRs, this is going to be totally amazing!

I agree, Mark! While there is already quite a network of remote SDRs and receivers in the world, the barrier of entry keeps getting lower and lower. It’s hard to imagine that $25 can buy an SDR that natively covers the shortwave and mediumwave bands!

There’s only one other requirement for an online SDR that Mark didn’t mention: a decent Internet connection. Sadly, this is the only thing keeping me from hosting a remote SDR here at my home. I considered purchasing a KiwiSDR like Mark, but my upload speed (0.2-0.3 mbps) is so terrible and so unreliable that I could only host one listener at a time at best. You can bet that as soon as my ISP upgrades our service, I’ll launch a web SDR as well.

Of course, I’m willing to bet that most SWLing Post readers have more than enough bandwidth to host a $25 remote receiver! Let’s make Mark’s vision a reality!

Shortwave Radio Recordings: Radio Baghdad, August 8, 1990

radio baghdad qsl

Many thanks to SWLing Post contributor, Al Quaglieri, who shares the following recording, QSL (above) and notes:

Here’s a nice recording I made of the first 13 minutes of Radio Baghdad’s English broadcast one day around August 8, 1990. It begins with some music and then there’s a newscast. For a couple of months, I sent such recordings down the phone line to CBS News in New York, who were eager to hear them. This, alas, is the only one I kept. Hard to believe it was nearly 26 years ago.

My how that does bring back memories! Thank you for sharing this excellent recording, Al!