ICOM ICR-75 vs. TECSUN S-2000

[RobRich]

I use a RTL-SDR V3 in direct sampling mode for casual HF listening in the den, as I do not have any desktop HF receivers currently there. Like Chris basically insinuated, it is not a solution for DX or selectivity, especially compared to something like a Airspy HF+ or better. However, it is less than $30, so.... It is where I usually tell people to start into SDR if they are not sure about dropping $200 for something better.

Luckily I was able to remove the lowpass filter I had inline without any significant issues, thus I can tune casually MW through UHF with point-and-click ease. Local AM stations, broadcast shortwave stations, regional SSB amateur ragchews, FM locals, NOAA weather, etc.

I do have substantial RF choking inline: a KD9SV SV-CMC common mode choke, plus ferrites on both the feedline and USB cables.

The big deal with RTL-SDR dongles is incredibly easy overloading in direct sampling mode. They have low dynamic range, among other issues, particularly at HF and lower. I typically use my 9' vertical ground-mounted over a few radials when listening via a RTL-SDR, even well into VHF. An outboard preamp just raises the noise floor and further lowers available SNR. An outboard preselector might be more prudent, but if going to the expense and/or hassle, you might as well start with a better SDR anyway.

[ChrisSmolinski]

An outboard preamp just raises the noise floor and further lowers available SNR. An outboard preselector might be more prudent, but if going to the expense and/or hassle, you might as well start with a better SDR anyway.

At some point, you've spent so much extra money putting lipstick on the pig that you'd be better with an SDR designed for HF use 

Note: I'm not disparaging the dongles in general, for VHF/UHF they're actually an incredible value IMHO. I have some running myself, one is decoding the various 434 MHz transmissions from all sorts of electronic doodads. Lots of folks use them for 1090 MHz ADS-B monitoring. And you can find tire pressure sensors on 315 MHz. I'm sure Fansome would approve of monitoring them 

[RobRich]

True enough. For a personal perspective, I have lots of the extra stuff collecting dust on shelves anyway. Preamps, preselectors, tuners, attenuators, etc.

I still have an even cheaper built E4000 dongle from back when the RTL-SDR fad started. Admittedly, yeah, that thing was largely useless for anything but basic experimenting.

My next significant SDR purchase probably will be an Airspy HF+. That seems to be about the current break even point for a SDR regarding decent HF performance versus cost.

[alpard]

yeah, I get the point.

They work fine for VHF and UHF, but for HF, you need something better than RTL-SDR.
I think SDRPlay is very popular here, and AirSpy is more expensive not very popular.

I still keep using the KiWi SDRs all over Europe for checking out if what I am hearing is either ghost image or the real signal, and also the HF band conditions etc.
I think the quality of SDR will further improve, and price will keep coming down.

[RobRich]

Received my Airspy HF+ Discovery today. I was thinking about the dual-port model for more easily using a dedicated VHF antenna, but the addition of extra preselector filtering moved me to the Discovery mode since HF is my main interest anyway.

Added a KD9SV SV-CMC common mode choke on the feedline before the SDR and an USB extension cable multi-turn wound on a couple of snap-on ferrites - probably mix 31 or 43.

I will spare a serious review as there are plenty online. Just quick a commentary that it is working quite nicely even with it currently connected just to my 9' ground-mounted vertical. Very low noise floor and good dynamic range, which hopefully will further enhance the performance of my 148' loop-on-ground.

[alpard]

I read good things about AirSpy.  I was contemplating buying one at one time, but am told that now 16bit 32Mhz 64Mhz SDRs coming out into the market. Maybe it is still  time to hold for the newer technology in SDR?

[alpard]

By the way, my S2000 is working great.  It is not a perfect or high grade radio, but it is adequate for hobbyist DXing.
It lacks various filters for QRM, that is only problem. But then, if the signal is that bad with QRM, how many radios with various filters can make it noticeably better, so that it becomes clearly readable from non readable?

[ChrisSmolinski]

I read good things about AirSpy.  I was contemplating buying one at one time, but am told that now 16bit 32Mhz 64Mhz SDRs coming out into the market. Maybe it is still  time to hold for the newer technology in SDR?

There's always newer technology coming on the market At some point you pull the trigger.

I have a Airspy HF+ Discovery that I currently use for decoding SSTV, it sits on 14230 USB 24/7. I also have one of the non-Discovery HF+ models, which is about the same performance wise (the Discovery may be a tad better), although I do like the fact that it has two antenna inputs, one for HF and one for the limited VHF range, vs a shared RF input on the Discovery.

FWIW my netSDR has a 16 bit 80 MHz sample rate ADC. I've had it for... let's see... April 2011 it seems. Still works like a champ 

[alpard]

So, 16bit SDR has been in the marker for many years?  It is just it was first time I saw the 16bit 32Mb SDR on eBay for sale. Before it was always either SDRPlay or AirSpy and their clones, or the cheap dongles for 20 box.

I was interested in the new RX666 and RX888 when I saw them a few days ago. I even almost bought it too. I am glad I didn't

And then there are many of the Malachite stand alone SDRs which look also very attractive too.  Interesting times

My question is whether these new tech SDRs will be able to copy the weak DX signals from South America on the tropical bands with their low power transmitters on the same antennas I am using now?  All my radios have been struggling copying the signals, and some days I stayed up until 2am in the morning trying to copy them, no joy.

[ChrisSmolinski]

So, 16bit SDR has been in the marker for many years?

Yes.

My question is whether these new tech SDRs will be able to copy the weak DX signals from South America on the tropical bands with their low power transmitters on the same antennas I am using now?  All my radios have been struggling copying the signals, and some days I stayed up until 2am in the morning trying to copy them, no joy.

My guess? Probably not. Your reception is likely limited by antenna performance as well as local noise/RFI levels. My advice would be to improve what you can there first, then look to see whether a better receiver would help further. It very well could, but tackle the antenna first. If you provide some detailed information about your yard (dimensions, distance to the shack, available trees, locations of obstructions & issues like power lines, any limitations on what you are allowed to put up, etc) I am sure you can get some useful suggestions.

[alpard]

Yeah, I thought that was the case. The receiver is not really going make too much difference once they are reasonably good ones.  Whether it was a 2k - 5k AOR or JRC radios, or a cheap Tecsun or old Sangean or dirt cheap XHData, they will all be copying the signals in similar way on the same antenna? I am not able to comment on the SDRs, as I have never owned or used it.

The antenna makes the signal heard or missed. So if one is into hunting that weak DX signals, then the first most important thing is a good antenna.
And as you say, your location and RFI situation will kick in.  The receiver will come next provided also there were the propagation.

My yard is not too big, it is about 15m x 15m, so I have a wire loop about 30m long in delta shape horizontally hung on the washing pole.  And I have a MLA30 now in the patio.  Not really great for DX, but then the band condition is not the best now is it?  I am thinking of putting out a vertical antenna, and add more wire to the wire loop. Trying to get more DX signals logged.

Provided all these elements got right, I am sure  good receiver will further help.

[ChrisSmolinski]

Yeah, I thought that was the case. The receiver is not really going make too much difference once they are reasonably good ones.  Whether it was a 2k - 5k AOR or JRC radios, or a cheap Tecsun or old Sangean or dirt cheap XHData, they will all be copying the signals in similar way on the same antenna? I am not able to comment on the SDRs, as I have never owned or used it.

I agree with the first part, the reasonably good radios. But I would not lump a "cheap Tecsun or old Sangean or dirt cheap XHData" into that category. No matter how good your antenna is, they are going to have serious problems.

The antenna makes the signal heard or missed. So if one is into hunting that weak DX signals, then the first most important thing is a good antenna.
And as you say, your location and RFI situation will kick in.  The receiver will come next provided also there were the propagation.

Correct, do the best you can antenna-wise. Because even if you have a high end receiver, if you connect a crappy antenna to it, you will have crappy reception.  And then RFI is another matter, often there is little you can do to solve that with an antenna, other than re-locating it. RFI is best solved at the source, by eliminating it.

My yard is not too big, it is about 15m x 15m, so I have a wire loop about 30m long in delta shape horizontally hung on the washing pole.  And I have a MLA30 now in the patio.  Not really great for DX, but then the band condition is not the best now is it?  I am thinking of putting out a vertical antenna, and add more wire to the wire loop. Trying to get more DX signals logged.

Provided all these elements got right, I am sure  good receiver will further help.

What is the RFI situation actually like? Walk around with a portable radio. No need to tune into a SW station, you want to listen for RFI (ideally on the bands if interest to you). If you encounter RFI, see if some parts of the yard have less RFI, that is where you want to put your antenna.   If your RFI situation is really bad everywhere though, then you may not be able to improve things past where you are now (other than preventing overloading, per your other post).

[RobRich]

I can get armchair copy from my now ancient Soft66LC4 SDR, which is I/Q sampled via a sound card, but the attached antenna and the arriving signals are the more the important factors there IMO. It is not much for weak signal work, but it is perfectly fine for listening to lots of powerful shortwave broadcasters.

Alpard, also take note that sampling like up to 32MHz of spectrum can be great, but sampling bandwidth is not an outright indicator of performance.

For example, the mentioned Airspy HF+ models use a 16-bit ADC followed by a DDC for decimation to an 18-bit output, but bandwidth is limited to a max 912KHz. For many people who are casual hobbyists, like me, that is more than enough to *visually* monitor on a waterfall at a time.

Sure if you are recording and/or streaming from multiple bands, like Chris does, then admittedly large sampling bandwidth can make more sense.

There are a litany of other specs involved, too. Internal noise floor, sensitivity, selectivity, dynamic range, etc. From your other thread regarding receiver overload, it seems like selectivity might be a distinct concern for your particular situation.

[alpard]

I have copied some good DX signals (rare and hard to copy and weak) with the cheap and old radios when the condition was great with just wire in the garden.

My location is in the residential area with no serious RFI.  During the day, sometimes the next door neighbour can use electrical saw, drills or grinder, which can be seriously bad RFI. But it lasts only for an hour or two. At nights, it is RFI free relatively.  But then when xyl put on the TV in the living room, it can interfere with my radios. But she put it off around 11pm, so it is actually RFI clean after that in this house.

I still think my antenna is not ideal for DX rxing. So will keep on experimenting and trying improve on that.

I can see Chris is SDR only user, whereas Rob has AirSpy but uses the vintage Trio R600 and 2000 and even FRG-7?   I have a FRG7 too. Still using it for DXing, and it works great.  But it can sound sometimes very noisy.  I like my Tecsun S2000, because it is a lot quieter receiver with good sensitivity and selectivity.

Rather than getting the old high grade radios such as Icom JRC or AOR or even Kenwood, I now feel it is better going for good SDRs.

[alpard]

I now picked up an ICOM R75.  It is a great rig, but TECSUN S2000 is still a good radio too.  R75 is more robustly made and has more features, and works great. But  S2000 has still its place = it is fast and easy to tune to the signals I am after, and the audio is mellow and rich.  They are different radios in audio quality and style.