Category Archives: Shortwave Radio

An inexpensive Windows tablet for portable SDRs?

I’ve never been a fan of tablet PCs. I have an old Android tablet that I occasionally use to watch Netflix and read eBooks, but when I want to interact with a computer, I typically want the convenience of a proper keyboard and the precision of a mouse or large track pad.

With that said, this year at the Winter SWL Fest, I was co-host of a forum called: “Time Travel, Teleportation & Spectrum Hoarding for the Contemporary DXer.” My good friend and co-host, Mark Fahey brought his Windows tablet PC and we used it to demonstrate how easily and effectively SDRs can be taken to the field and spectrum recordings can be reviewed practically anywhere. Indeed, Mark tunes through his spectrum recordings while taking the train to work! (How cool is that!?!)

This week, I reviewed a guest post about portable SDRs by London Shortwave; afterward, I decided that I must begin the search for a Windows tablet. Since I would only use this tablet for portable SDR work, I really want to keep it as affordable as possible ($200 US or less).

It appears to me that there are a few things that you must overcome in a portable SDR package including: mitigating internal noise produced by the tablet and accessories, and the ability to power the tablet and the SDR at the same time.

Windows Tablet Wishlist:

Inexpensive (less than $200)
Enough speed and memory to run SDR applications and record spectrum to an internal SD card or external portable drive
Separate USB and power ports or the ability to power both the tablet and SDR at the same time

My choices so far:

Readers: Your recommendations and advice are most welcome! Please comment especially if you have experience using tablet/SDR combos.

The Mighty KBC: Summer frequency changes/additions

Roundup of software defined radios

Bonito adds new products

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The Bonito MegaLoop ML200

I’ve just heard from German manufacturer, Bonito, who has added several new products to their product line:

MegaLoop ML200: The MegaLoop is a 5 meter active stainless steel loop antenna that can be used outdoors. The MegaLoop ML200 ships with a Dual Power power supply (including the ability to power via USB).

Bonito notes that the Megaloop ML200 is currently available for a special price of 279,00€ (incl. 19% VAT) at HamradioShop.net.

The MegActiv 305

MegActiv 305: The MegActiv 305 is a compact antenna designed for low-noise reception between 9 kHz and 300 MHz. It has a radiating element of 18cm and can be powered with 5-15 VDC (max.120mA) or with the supplied Dual Power unit CPI 1000DP via USB.

The MegActiv 305 will be available for purchase end of April for an introductory offer of 174,99€ (incl. 19% VAT).

Fenu at fenu-radio.ch will review a sample of the MegActiv 305 in the near future.

OVP1000 Over Voltage Protector: The OVP1000 is an in-line over voltage protector for your receiver. It’s designed to dissipate current pulses caused by nearby thunderstorms. The OVP 1000 protects against high power surges in three ways:

The OVP1000

A gas discharge tube with 60V firing voltage, max. pulse leakage current 1kA (8/20µs)
An ultra-fast ESD diode (30KV; max. pulse power 350W (8/20µs)
Blocking DC voltages (up to max. 100V) at the input and output.

The OVP1000 is available now for 59,00€ at Hamradioshop.net.

For full details about these new products, please visit Bonito’s blog.

And many thanks to Bonito who is a proud sponsor of the SWLing Post!

Vanuatu’s radio services restored

Deutsche Welle to close Kigali relay March 28, 2015

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DW’s relay station in Kigali (Source: Deutsche Welle)

Many thanks to SWLing Post reader, Mike, who writes:

“I wanted to pass on a quick (and unfortunate) word that Deutsche Welle will be closing its Kigali, Rwanda relay on March 28th. This word came from the Wavescan program on WRMI. I would highly recommend that anyone who would like a QSL response from DW should get their correspondences in as soon as possible. It seems that the site will be dismantled shortly afterward. In addition it seems that tests are ongoing at RFI’s Issoudun site by DW to replace some of the broadcasts that used to originate from their Kigali relay.

I find the closing of another landmark relay a greatly displeasing event especially due to the short time frame between the announcement of the closure and the actual closure date. I find it surprising as well due to the lack of mention of any recent budget cuts at Deutsche Welle.”

As Mike mentions, the relay is scheduled to close on March 28, 2015–if you’d like to log this site, you’ll need to do so very soon. Click here for current schedules. Kigali is Deutsche Welle’s only remaining relay station.

RadioWorld magazine also posted a short news item about the Kigali closure–click here to read.

Wyn compares the SDRplay RSP and Airspy

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After posting about the price reduction in the SDRplay RSP, Wyn Evans commented with his comparison of the SDRplay RSP and Airspy (another popular low-cost wideband SDR). Wyn writes:

I have both and Airspy and the SDRplay RSP. I like them both, but on balance I prefer the RSP. The pluses of the RSP over the Airspy for me are:

1. Sensitivity – At least with my Airspy, I find the sensitivity a bit disappointing. The RSP is on the other hand excellent. I read on another forum one user claiming that the difference between the two was as much as 3 dB. I can’t verify the number, but I would not be surprised if it were about right

2. HF support – Absolutely fantastic, no up-converter needed

3. ZIF or Low IF. In ZIF mode, with calibration, you can get image free reception

4. Programmable filters. You can change the selectivity from as low as 200 KHz to the full bandwidth of 8 MHz, This is a huge plus for DX-ing if you live in an area with very strong local stations

The plus for the Airspy is that there is does cover the gap between 380 MHz and 430 MHz, with the RSP doesn’t. For some people, this is a really big deal.

Both seem to have about the same dynamic range, which isn’t surprising as despite using different tuners, the ADCs seem to be virtually identical.

So in summary, I think both are pretty good products with pluses and minuses, but at this new price point, as long as you don’t need to use 380 – 430 MHz, there is really only one I would choose now.

Many thanks for your comparison, Wyn. As I stated before, my impression of the SDRplay RSP is quite good so far. I live in a very RF quiet area–I am curious if anyone has used the SDRplay in urban areas, near local broadcast stations and experienced any overloading or serious imaging.