R820T2 SDR Radio Receiver

 R820T2 SDR Radio Receiver

My current direction of travel, with amateur radio and other
things in my life, is to downsize so I can continue with my radio hobby in
smaller accommodation when the time comes. I am therefore a convert to Software Defined Radios
(SDR). These are tiny radio receivers, typically the size of a memory-stick
dongle, and controlled by software on a computer. This means the equipment size
is minimal and the cost/performance ratio of an SDR radio can be very high.

I recently bought a R820T2 SDR from Nooelec on Amazon. I had
previously owned a R820 SDR (see earlier post) but the performance was very disappointing
and I recycled it. I needed another receiver because I wanted to monitor marine
AIS signals without tying up one of my other SDRs or my main transceiver. I had
heard that the performance of the R820T2 was much better than previous R820
radios and at less than £25 I decided to give it a go

The package arrived and contained, as advertised, the
R820T2, a small (300mm) telescopic whip antenna. Before using the R820T2 as a
radio receiver, rather than as a Digital TV, it is necessary to change the
Windows driver using a little utility called ZADIG. This is very
straightforward and there are plenty of instructions on line how to do this so
I won’t repeat them here. Do not
load any TV software that might come with the SDR and of course set a ‘Restore’
point before changing drivers so you can back out in the unlikely event of
something going wrong.

That done, plug the SDR into a USB port on your computer and
plug your antenna into the MCX female connector on the SDR. If you do not want
to use the supplied whip antenna adapters from MCX to SMA, BNC etc. are
available from electronics suppliers and these make it easy to connect other antennas.

Next, start your SDR software. I use SDR Console and SDR#
(SDR Sharp) which are free downloads. Select RTL Dongle or RTL USB from the ‘radio’
menu, set the frequency you want and the mode and then ‘Start’ and you should
be in business.

So what does the R820T2 + software do?

• ·        
  It tunes from about 25 MHz to around 1.8GHz so
  it covers the VHF and UHF amateur radio and commercial bands
• ·        
  It also does the 10m amateur band with limited
  performance.
• ·        
  It does not care what mode you want to receive –
  SSB, AM, CW, FM, Digital etc. as this is taken care of in software on your computer.
• ·        
  In addition to amateur radio, you can receive
  broadcast station, marine voice and AIS signals, aircraft voice and ADSB
  broadcasts and much more provided this is legal where you live.
• ·        
  You can receive signals from amateur radio,
  weather and some scientific satellites, including ISS.

I will say more about AIS, satellites and ADSB other posts.   

I found the 820T2 performs very well and not much worse than
the more expensive SDRs that I own. Filtering is much better than with earlier versions of the R820 SDRs. Certainly works well enough for a beginner to
enjoy or as a secondary receiver for a licenced amateur radio operator.  I use it as a second receiver when operating
VHF and UHF contests as I can see station pop up on the software waterfall
display. Although the whip antenna is small, I found it actually works
surprisingly well if it is located in a good position (high up by a window for example), but obviously ‘real’
antennas will give better performance.  

In summary the R820T2 and one of the software programmes make a very credible VHF/UHF all-mode
receiver and a fraction the cost of ‘real’ radios. It takes up almost no space
so is ideal if you live in restricted accommodation. Its performance is vastly
better than previous R820 receivers and would make a great Christmas or birthday present
for anyone interested in radio or thinking of starting out in the hobby.

Please share your experiences with R820 SDR Radios by commenting here. 

SignaLink USB Digi-mode Interface

Digi-modes are attractive to me as they enable long-distance contacts with my low power and limited antennas. There are numerous computer programmes for the different modes and many multi-mode programmes. They all have one thing in common, it is necessary to make multiple connections from your computer to your radio

.

• Audio out of the computer,
•  Audio into your computer,
• ‘Press to talk’ to control when the radio listens or transmits.

This would require several cables and level settings to get satisfactory operation. To make matters worse, my old computer gave up the ghost and my new computer has no microphone socket, so I have to use an external sound card – more wires and more things to configure.

I use my computer for many things, not just amateur radio, so I cannot leave the amateur setup permanently configured. This meant the setup time was too long and too error prone for a quick go on digmodes. Then, my life changed! I came across the ‘SignaLink USB’ interface unit which has its own internal sound card and only requires two cables. (plus a couple of optional connections that I don’t use).

      

                  

Signalink Front and Back

First thing to say is that it’s small 80w X 100d X 40h (mm, in case you are wondering) which is entirely consistent with my station design philosophy. It only requires two cables:

• ·         From the unit to a computer USB port (supplied with the unit)
• ·         From the unit to your radio. These are bespoke cables that you buy when you order the unit if you do not want to make your own.

The SignaLink USB comes with comprehensive instructions and more help is available on the www.tigertronics.com web site if you need it. Documentation is good.

Setup is very easy. Internal adjustments are necessary to match the SignLink unit to your radio. This requires the unit to be opened by removing the four Allen bolts on the front of the unit and sliding the innards out. There are two ways to configure the unit:

• ·         Use the supplied jumper wires using the diagrams available on the supplied CD or from the www.tigertronics.com web site. This is the best option if you will want  to change radios often.
• ·         Fit a ‘plug and play’ jumper module for your radio that can be bought as an extra. This is the best option if you only want to use the SignaLink with one radio.

The process is very straight forward, but do read the instructions before you start.

This brings me to the only criticism I have – the Allen bolts are not metric size. If you are in Europe, this is a real pain because the old Imperial size Allen Keys (Wrench) are very hard to find here. One is supplied so don’t lose it! In my professional life, I would never buy equipment that used non-metric bolts etc. for use outside USA.  This would cause maintenance issues because the imperial tools, which were usually supplied, would invariably get lost or stolen.

Signalink Inside

Once the internal unit is back in the case and the Allen bolts fitted you can begin setup. This is very clearly described in the supplied documentation. This does involve messing around with the Windows sound controls, to set up the SignaLink internal sound card, but once this is done you seldom need to go there again. This is because the SignaLink has analogue volume control knobs on the front for transmit and receive so adjusting levels while operating is very easy.  

That’s it, you are almost ready to go. I leave the SignaLink connected to my radio so all I have to do is connect the SignaLink to my computer and switch it on. The SignaLink is powered from the USB port so no need for an external sound card or power supply.

Start your digi programme and select “USB Audio Codec” for the input and output. Check the receive signal level and adjust the RX control on the front of the SignaLink. Send a tune signal and adjust the TX control on the front of the SignaLink for the correct level (then back it off a fraction of a turn!).

I have tested the Signalink with the following software:

• ·         MultiPSK – the Swiss Army knife of digimodes.
• ·         WSJT (FT-8, WSPR etc.).
• ·         SeaTTY – for receiving weather reports etc.
• ·         WinWabler.

It works fine with these applications, and I don’t doubt, with many others as well. It is now very easy to get on the air and so I am able to do digital sessions even when time is limited.

As the Signalink unit is small and simple to set up, portable digital operation such as a SOTA expedition, with a tablet for example, is quite feasible. Unfortunately, at the time of writing, UK is in lockdown for the CV-19 pandemic so I have not tried this yet.