Category Archives: Radios

The XHDATA D-808 and longwave: how to build an effective antenna

Many thanks to SWLing Post contributor, Mad Radio DXer, who writes:

I said I would share my results for attempting to receive LW signals on the XHDATA D-808, & if I can use a longwire to improve reception on this radio. This was after posting videos when I used around 50 metres of longwire connected to the D-808 for improved Medium Wave reception & to prove it works.

This first video shows that it is not possible for LW, no matter if I connect the 50 metres longwire to the 3.5mm input or the whip antenna. I also compare reception of the same station with the Degen DE1103 PLL using the 3.5mm input. The Degen DE1103 still had better reception even when I used the whip antenna extended at the very minimum when using the LW/MW external antenna trick. I know I should have used the internal ferrite antenna of the Degen compared to the D-808, but in any case I did try off camera & reception was about the same. So unfortunately the D-808 was never going to win this round.

However, there is a solution.

The answer? Build yourself a Long Wave induction antenna as shown in the second video [below]. I made one some time ago, as I grew frustrated at how poor the Tecsun radios were on this part of the band & that there were no LW induction antennas available to buy. I tried a signal on 207 kHz which is RÚV Rás 2 from Iceland. Either a radio with a very good internal antenna or a good external antenna is needed to receive this station at my QTH in southern England.

Placing the D-808 on the induction antenna resulted in a very pleasing result, which was it did get reception of Iceland on 207 kHz. So this shows that it is possible to DX on the LW bands with the D-808 with some “external help”.

For anyone interested making a LW induction antenna as shown above, here is a link to a video that has basic instructions & further results. It may be a very simple build & finish what I did, but for me the most important thing is that it works.

I hope my comments & videos will be a great help to all. Happy DXing.

Regards,

Mad Radio DXer.

Excellent–your comments and videos are most welcome! There are quite a number of SWLing Post readers who are avid longwave DXers. I love the simplicity and efficacy of your longwave antenna–something anyone could build.  A clever upgrade to the affordable D-808. Thank you for sharing!

Radio Deal: Eton Traveler III $35.83 shipped via Amazon.com

Amazon has just posted an excellent price for the Eton Grundig Edition Traveller III shortwave portable: $35.83 shipped!  This is the lowest price I’ve seen for the Traveller III since December when it hit this lowest price for a very brief period of time. As with any Amazon spricing, this could end at any time.

Click here to view on Amazon.com (affiliate link).

Mark spots a number of radios in “Brooklyn Nine-Nine”

Many thanks to SWLing Post contributor, Mark Hirst, who adds the following to our growing archive of radios in film. Mark writes:

A clutch of radios, this time from Brooklyn 99:

The first is what looks like a scanner behind Terry Jeffords, then an unidentified radio in the book case behind Captain Ray Holt, and finally what I think is a AOR 8600 on the table next to Amy Santiago.

Many thanks, Mark! You have very sharp eyes–especially spotting the AOR on the table in the last scene!

Please comment if you can identify this radio gear!

The AirSpy HF+ R3 bypass modification

After SWling Post contributor, Guy Atkins, posted the survey results of his excellent Elad FDM-S2  vs AirSpy HF+ weak signal comparison, I received a few questions about the AirSpy HF+  “R3 Bypass” modification Guy mentioned in his post.

Guy has not yet performed the modification on his HF+–neither have I–but he points out that others have noted it: “significantly boosts sensitivity of the HF+ from longwave up to about 15 MHz, without any noted overload issues.”

I reached out to AirSpy president, Youssef Touil, for a little more insight about this modification. Youssef replied:

During the early phases of the design R3 was a place holder for a 0 ohms resistor that allows experimenters to customize the input impedance. For example:

  • A 300 pF capacitor will naturally filter the LW/MW bands for better performance in the HAM bands
  • A 10µH inductor would allow the use of electrically short antennas (E-Field probes) for MW and LW
  • A short (or high value capacitor) would get you the nominal 50 ohms impedance over the entire band, but then it’s the responsibility of the user to make sure his antenna has the right gain at the right band
  • A custom filter can also be inserted between the SMA and the tuner block if so desired.

Click to enlarge. (Photo source: RTL-S1DR.com)

R3 and the nearby resistors have been intentionally left outside of the RF shield, and their size was picked to be big enough to allow anyone to play with them. You will notice the size difference with the rest of the components.

In general, unless one knows what he’s doing, it’s not recommended to alter a working system. “If it’s working, don’t fix it”. But, we are hobbyists, and not doing so leaves an uncomfortable feeling of something unachieved. Most brands addressing the hobby market leave some tweaks and even label them in the PCB.

The main purpose of the HF+ is the best possible performance on HF at an affordable price. This is to incite HAMs to get started with this wonderful technology while using an SDR that isn’t worse than their existing analog rig.

The MW/LW/VLF crowd may have slightly different requirements, but that can be addressed by shorting a resistor.

Regards,

Youssef Touil

Thank you, Youssef, for replying to my inquiry so quickly and thoroughly.

No doubt, I too will eventually modify R3–it’s very difficult not to experiment, especially when a product was designed with the experimenter in mind.

I really feel like AirSpy has knocked it out of the ballpark with the HF+. For those of us primarily concerned with HF performance, this SDR is very hard to beat–especially at its $199 price point!

Video: Comparing the SDRplay RSP1A and Airspy HF+ on HF & MW

Many thanks to SWLing Post contributor, Ivan Cholakov, who shares the following video where he compares the SDRplay RSP1A and the AirSpy HF+ software defined radios on shortwave and mediumwave:

Click here to watch on YouTube.