SDRPlay RSP1 and HDSDR initial observations

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N9JIG

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My friend Ted had piqued my interest a year or so ago in Software Defined Radios (SDR's) but I was too busy selling and buying homes, retiring and moving to get involved with it. I was at HRO here in Phoenix the other day getting some antenna parts and saw one in the display case and decided to check it out. I bought an SDRPlay RSP1 ($150) and brought it home to play. Made in the UK, The SDRPlay is distributed exclusively in the USA by Ham Radio Outlet.

The RSP1 is a small plastic box with an SMA antenna jack on one side and a USB Type B (like those used on printers) on the other. There is a label on the bottom with the serial number and the top is embossed with the name. It does not come with the cable or any other accessories. Other than the cable (which you probably have a half dozen or more laying around) no other accessories are needed. It is powered off the USB port, so if your USB ports are underpowered you might want to use a powered hub.

I went to the SDRPlay website and followed the excellent step-by-step instructions to download some of the several applications to run it. The first package I tried was HDSDR and it worked just as it said it would. I tried it on my Windows 10 machine as well as the Windows 7 environment on my iMac. There are native OS-X, Linux and Android versions of applications for this SDR, of which I will try the Mac versions later. There are other applications including SDR Sharp (SDR#), which I was unable to get to work so far but I haven't tried to troubleshoot the issues.

HDSDR is immensely configurable and seems to work well. The installation was easy and the only issue I had was there were never any instructions to press the "Start" button to start receiving. It took a little experimentation to figure this out and once I did all was well with the world. The standard modes like AM, FM, USB, LSB, CW and DRM (Not DMR!) are selectable. From what I have heard if you want to do other modes like P25, TRBO, NXDN etc. there are other applications that will process it. That will have to wait a while as I get my feet wet with this little gem. The receiver bandwidth is adjustable so you can switch from broadcast (wide) to two-way (narrow) with several steps.

As for the receiver itself, it seems very sensitive, so much so that I had to reduce the gain (actually increase the gain reduction) dramatically to prevent overload and images. I have it connected directly to an AntennaCraft ST-2 in my attic. (BTW, this makes for a great HF receiving antenna as well as an awesome scanner antenna!). I was picking up WWVH at full quieting on 5, 10 and 15 MHz. during the late afternoon and early evening and then WWV a little later on 10 and 15 MHz. Various other HF broadcasters like WTWW and Radio Havana were booming in and the various HF ham bands were doing well. I even discovered a new (to me anyway) HF NOAA/USCG weather broadcast from California.

On VHF and UHF it was also pretty sensitive and a careful setting of the gain reduction control is needed to provide best results. It had to be set high enough to allow the squelch to be effective and low enough to allow the spectrum display to be useful. As the control is a “Gain Reduction”, the higher it goes the less sensitive the receiver is. After asking a couple questions on a couple forums on RadioReference and Facebook I had a much better understanding of how that worked and found that a setting of about -75 to -60 db worked best on HF and about -50 on VHF worked best. I live in a fairly radio-quiet area out here in the hills but there is an antenna farm on the mountains a dozen miles away that does present some strong signals.

What I have not yet played with is scanning (vs. just tuning around) or importing freq lists. I have seen various downloads available that one can import freq lists to scan but again that is for another day. I want to try other applications first and see what works best for me. Another thing I haven’t played with is streaming or additional audio processing. These are on my list of things to play with down the road.

One thing I would suggest for the manufacturer is to put the USB and antenna jack on the same panel. This allows one to keep the cables tidy, having them on opposite sides makes one cable always visible unless you hide the box someplace. I also might have considered a metal enclosure to help reduce outside noise invasions.

My plans are to connect this to an antenna switch so I can easily swap out the antenna used. I don’t think insertion loss will be much of an issue as I think an attenuator would be helpful much of the time anyway. I might also look into preselectors, Ted had mentioned this before as a good tool and he is usually right about these things.

I was able to hear stations on this that my Icom R8500 did not, on both HF and VHF with the same antennas. So far I am very impressed with this little box as a receiver and anticipate many hours wasted playing with it!
 
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Voyager

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Is there any reason to not hide the box?

I for one prefer the arrangement of the connectors on opposite sides for two reasons:

1. It allows the unit to be mounted on a laptop with the antenna stocking upward but with monimal strain on the USB connector, and more importantly

2. It likely reduces noise from the USB connection on the antenna input.

I have to wonder about the plastic box. If it's as sensitive as you say, what is to keep interfering signals out of the guts?
 

N9JIG

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I haven't opened the case so there might be adequate shielding inside but somehow I doubt it.

I guess the placement of the connectors is subjective, I suppose there is no reason not to stash it someplace. I was thinking of velcroing it to my RadarBox but I am afraid there would be noise generated from it. I might just mount it under the desk up and out of the way someplace.
 
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