CHENGDU NEWSTAR DR111

The Newstar DR111 arrived here by the Swiss Post via FedEx, well packed in a DHL plastic bag and in good condition. I paid USD 120.- for the radio and USD 45.- for the transportation from Hong-Kong. On top of that FedEx presented a bill where they charged me a total of EUR 27.41 in VAT, their handling and import duty - 1.5 kg from China cost EUR 0.71!

The DR111 is 275mm wide, 90 mm deep, 115 mm high and weighs 825 gram. The controls are rather self-explanatory and you soon get used to the operation. The only draw-back is that the clocking of the pushbuttons seem to be a bit on the slow side, so one needs to pause when pushing the same button repeatedly (when setting the frequency). It would have been nice to have an oldfashioned volume control instead of the step function. Especially the step from the first to the second level could have been divided into three, as the increase in volume is too much. Especially if you are using the DR111 on a bedside table you feel the difference.

The telescopic antenna is used mainly (?) for the Short Wave and FM reception. For Long- and Medium Wave there are two separate Ferrite Antennas built into the set. An AC/DC Power Supply with 5 Volt output is used to run the DR111 off the Mains. There are no built-in batteries in the radio, so it cannot used as a portable set.

It has now been playing DRM fairly well for a while, both on medium- and on short-wave. However, the scan function on DRM leaves a lot to wish for as you'll be lucky if it stops on a DRM TX at all. Mind you, this morning it did stop on BBC on 7355 kHz and yesterday it managed to halt on REE on 13720 kHz. Just for my curiosity, I pressed scan half an hour into the TDP transmission on 6015 kHz and during the last 30 minutes the DR111 did NOT stop again before the transmission was over - despite a solid RF signal here 470 km away from the TX.

SOME MEASUREMENTS ON RECEPTION AND AUDIO QUALITY

Fig. 2

Fig. 3

Fig. 4

A close-up plot of the last four steps of the volume control shows the steep fall towards zero volume. It would have been better to have had a smoother ending.

In the meantime the manufacturer told me on 1st June2012 that they will adjust this issue in the next firmware release.
 

Fig. 5

The volume control in the latest firmware version 723 from July 2012 has been changed from 17 to 39 steps. The result is much better than in the previous version. Now you can put it on the bed-side table an turn the volume down very low.
 

Fig. 6

The Selectivity was measured at 11830 kHz with 50 µV RF Input level in 50 Ohm and modulated with 1000 Hz, 60% AM. The signal generator was adjusted in 1 kHz steps up and down from the receiver frequency and the AF output was measured in dB relative to the center frequency. Three measurements were done with 1 kHz (yellow), 5 kHz (red) and 6 kHz (blue) kHz IF bandwidth.
 

Fig. 7

The signal generator was tuned to 20000 kHz and its output level was adjusted to +80, +60 and +55 dBuV respectively. An AM scan was performed for each input level. On 21640 kHz a tone was heard in the loudspeaker. On the other frequencies listed below the DR111 stopped scanning, but nothing was heard in the speaker. There are no data available for IF frequency and no information on whether the receiver is a single or double conversion superheterodyne. The results are shown in the table below:
 

Fig. 8

The graph below was plotted at 1296 kHz on Medium Wave. An abrupt increase in the RF input level causes the DR111 to reduce (IF?) gain in steps. This can be heard in the loudspeaker. The audio output in the speakers is fairly constant at RF levels above 1.5 µV. Below 1.5 µV the audio output decreases rapidly. There is no noise att all in the loudspeakers in absence of a signal or at very low RF signal levels.
 

Fig. 9

AM Audio Response

The Audio Response was measured by setting the signal generator to 60% AM modulation and the modulation frequency was measured from 100 Hz to 6000 Hz. Two series of measurements were done, one with 6 kHz IF bandwidth (blue curve) and the second with 4 kHz IF bandwidth (red curve). The result is shown in the graph below.
 

Fig. 10

In a previous test (with the Morphy Richards radio) I took my old ITT Schaub Lorenz Touring T60 from the 1960's as a reference receiver. The Schaub Lorenz sounds very pleasant on FM. I compared this radio with the AF output from the DR111. The audio frequency response in the Schaub Lorenz is rather linear from 100 Hz to around 20 kHz. Doing the same test with the DR111 shows a better audio frequency response compared to the Morphy but it could be better. Above 4000 Hz the Newstar DR111 has a roll-off of 20 dB / octave which leaves little output of the higher frequencies. Still, when listening to an FM station, the sound is not that bad anyway.
 

Fig. 11

The Audio Frequency response in DRM mode

Looking at the output from the signal generator on a HP Spectrum Analyzer the sidebands with the DRM � 12 kHz were clearly visible. The DR111 was tuned to 8000 kHz. The output level from the signal generator was set to -47 dBm (1 mV in 50 Ohm).

I made the measurements in the Earphone output jack (3.5 mm Jack). The result was positive. The frequency response is not linear. But the reception of DRM signals is still loud and clear.
 

Fig. 12

Power Consumption with the 5 Volt DC adapter (original design)

The DANGER of connecting anything else than the 5 Volt DC Power Supply!

Fig. 14

Next I soldered the 7805 three-pin regulator to the shield case near the DC jack and wired a 4.7 �F/25V on the input pin to ground and a 22 �F/16V on the output pin to ground. Finally the red wire was soldered to the input pin of the 7805 and the yellow wire was soldered to its output. The DR111 now needs an AC/DC Mains Adapter with an output of at least 9 V (minimum current capacity of 0.5 A) instead of the original adapter's 5 V DC. The power supply must be capable of delivering at least 500 mA, otherwise the DR111 might re-boot during power up. Interestingly, after this modifiaction, the total power consumption of the radio became lower than before.

Fig. 15

The sensitivity in AM Mode measured with a signal generator (I can only measure sensitivity on AM) is in fact not that bad - at least if you look at Fig. 2 a bit up on this page. But with no documentation or schematics available, it is hard to say why the performance on the telescopic antenna - to my liking - is a bit weak. When I switched to my roof-top active antenna I got much better reception.

Before I connected anything to the external antenna jack I checked if it was resistive or not. It was. I checked the value, and it was about 1.4 Mohms. Therfore I am feeding the active antenna to the DR111 with a capacitor in series, not to let any 12 Volts DC from the antenna's coax cable into the front end of the DR111.

I recorded some data for 9780 kHz (REE) on the internal telescopic antenna and on my modified PA0RDT active antenna. I got one to two S-Meter segments lighting (in AM mode) on the internal antenna with 19-21 dB SNR on DRM, compared to 3-4 S-Meter segments (in AM mode) with the active antenna with 24-25 dB SNR on DRM. That is a >20 dB (factor >100 at least) difference. The REE signal is pretty strong here in Switzerland - about 0.6-1 mV / 50 Ohm. On the FRG-7700 the SNR was around 27-28 dB.

A little later on 9850 kHz (RUVR) I got more or less only 0 (zero) S-Meter segments (not) lighting (in AM mode) on the internal antenna with 21-22 dB SNR on DRM, compared to a steady 2 S-Meter segments (in AM mode) with the active antenna with 25-26 dB SNR on DRM. That is a considerable difference too. The RUVR signal was not so strong - about 0.1 - 0.11 mV / 50 Ohm. On the FRG-7700 the SNR was around 30 dB.

I did another test with the DR111 connected to two signal generators, one on 6175 kHz and the other on 7545 kHz. With a -50 dBm signal from both I got an audible, rather strong signal on f1 + f2 = 13720 kHz in the DR111. -50 dBm is about 0.7 mV in 50 Ohms. It is hard to say whether this could be a problem in DRM if there are strong stations on unfortunate frequencies which adds or subtracts interfere with the DRM frequency.

Since the new firmware V790 was published in the beginning of August 2012, the DR111 became much more pleasant to use. The muting of the AF when tuning either with the tuning knob or with the up/down buttons was removed. Now you can tune the bands in AM and FM and hear what you are tuning into. I got another DR111 so I can compare the performance between the two, and I found out that the second receiver works much better on Long Wave and Medium Wave than the first receiver did - or does. I modified my first receiver so instead of the ferrite antennas I use the telescopic antenna instead. To be honest, my first receiver got part of my modified PA0RDT Active Antenna built into it and this modification makes the DR111 even more sensitive on Short Wave.

Lately I have monitored several DRM transmitters using only the built-in telescopic antenna. The reception is great on both receivers. Up to this date I have uploaded about a hundred logs on my Twitter page. Go to Twitter an look for @TerjeIsberg and see for yourself.

Adding a part of my modified PA0RDT Active Antenna into the DR111 makes the DR111 even more sensitive on Short Wave. A significant improvement on both AM and DRM was achieved with this modification.

The high input impedance of the tuner in the DR111 eliminates the need for the emitter follower in the active antenna. The internal supply voltage is 5 Volts, so some resistor values needed to be changed. I mounted the components on a small printed circuit board near the ferrite antennas.

The yellow wire in the picture below is connected to the telescopic antenna, the white wire goes to the Short Wave tuner, the red wire is +5 Volts and the blue wire is connected to DR111 ground (0V). The printed circuit board is double-sided. The rear side is used as a ground plane for best RF stability.

Fig. 16

The "Half" Active antenna built into the DR111

Logging DRM broadcasts

If you want to make DRM logs, be sure to set the DR111 clock to UTC. That is the time that will be written to the memory card in the DR111.

The DRM reception logging function records various data during a DRM session. To enable the logging function, first create a folder with the name "drm_log" (without quotes) in the root directory on a SD card. The DR111 will recognize this folder and create reception logs under this folder automatically. Reception log can be plotted with the DRM Log Plotter. The DR111 can only handle SD cards with 8 GB or less capacity.

To log a DRM transmission, do like this:

• Switch on the DR111 and tune in to a DRM transmission
• When you hear the sound in the DR111 speakers, insert the SD card into the slot
• At the end of the DRM transmission, be sure to switch the DR111 to Stand-By.
• In Stand-By, remove the SD card and store it or insert it into the computer's card reader to evaluate the log.

How to add a 12 kHz IF output to the DR111 for different purposes

How does this receiver work? Just out of interest I checked all the pins on the connector of the radio module set to DRM mode with an oscilloscope probe. To my surprise I found an AC signal in the outer row on pin 4 from the left. The pin has DC voltage on it, so I connected an isolation transformer via a 1 uF capacitor to avoid current or short circuits. There is 12 kHz (or about 11.4 kHz) signal present both in AM and DRM, so it doesn't matter which mode the DR111 is set to operate in. The signal is sufficient to feed to the Line Input of the computer.

Fig. 18

The isolation transformer was simply soldered to the shield cover of the radio unit. The 12 kHz earphone jack is seen to the right in the picture below. The advantages in DRM are that your DReaM logs will get the correct time instead of the unstable time stamps provided by the DR111 and there are no time lag when logging for several hours. Another advantage is that it is possible to search the bands in AM mode for DRM signals. In AM mode you can monitor what you receive in the loudspeaker of the DR111 which is not possible in DRM when the speaker is silent until a decoded DRM signal is present.

Another advantage in AM mode is that you can use the DReaM in analog mode and profit from the different receive modes (AM, LSB, USB, CW, FM) and filter bandwidth settings. The DReaM version 2.1.1 also has a powerful noise reduction tool which makes a big difference in listening to short wave.

Fig. 19

Fig. 20

In case you wonder what are the components in front of the active antenna board, those are two smooth operating push switches which I use for adjusting the DR111 frequency up and down instead of the two TACT switches in the middle of all the switches on the top.

How to make the DR-111 a portable receiver

One drawback with the DR-111 is that there are no built-in batteries, so you cannot take it with you to places where there is no AC power available. So I invested in a 5200 mAh GP Power Bank with 5 Volt output which I connected to the USB socket on the DR-111with a home-made USB-USB cable.

Fig. 21

Previous experience with power banks were RFI (Radio Frequency Interference) in form of switching noise way up in the shortwave bands. This kind of noise made listening almost impossible because of hissing sounds which blanked out the wanted signals. This particular brand from GP is very quiet. Even if the battery is placed very near or on the DR-111 it won't cause interference.

Fig. 22

A practical test with this power supply during a period of two weeks with daily listening proved successful. 17 DRM broadcasts were monitored over a period of more than 13 hours on one charge of the Power Bank.

Comparing receiver sensitivity vs. different power sources

Below is a table showing the sensitivity of the DR-111 using different power supplies, including the GP Power Bank.

• Frequency: 12005 kHz, just randomly chosen
• Modulation: AM 1000 Hz, 60%
• Sensitivity was measured for 20 dB SINAD

In fact, the most quiet power source was the GP Power Bank. The second best was my lab power supply from Alpha Elettronica, the third best was the Linocell charger I bought to charge the GP Power Bank. The power supply that came with the AVION receiver from India was the noisiest.

• The ZIP file with the new Firmware
• One SD/SDHC Card (8GB or less capacity)
• A computer
• Your DR111 Receiver

2. Prepare the SD card and the Firmware files:

• Unzip the Firmware file to a temporary directory. You will find three files named Part1, Part2 and Part3
• Insert an SD/SDHC card into the computer and format the SD/SDHC card to FAT or FAT32 format (if it is not already formatted)
• Copy the three files part1, part2 and part3 of the firmware to the root directory of the SD card
• Remove (eject) the SD/SDHC card safely from the computer.

• Power off the receiver by pulling out the DC plug from the DR111
• Insert the SD/SDHC card with the firmware files into DR111 SD card slot.
• Power on the receiver by inserting the DC plug to the DR111
• The loading of the new firmware will start automatically. The update files will be verified and then the update follows. At the end a message "update finish, please reboot" is displayed.
• Now, power off the receiver by pulling out the DC plug from the DR111
• Remove the SD card from the DR111 SD card slot and wait 10 seconds, then
• Reboot the receiver by inserting the DC plug to the DR111. The DR111 will light up and the new firmware is active.

You will also notice that you have lost all your preset stations and you have to set the clock and the date etc. all over again.

Download the zip file and save it in a temporary folder. Unzip the files and follow the instructions above under "How to load a new firmware to the DR111".

You also agree to that if you decide to make any of the modifications described in this article, you do it at your own risk.