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Author Topic: To Dongle or Not To Dongle  (Read 503 times)
WE1X
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Posts: 333




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« on: Yesterday at 04:46:26 AM »

Okay..here we go.

About 18 months ago I was able to use an RTL-SDR dongle with HDSDR software to create a great panadaptor for the Icom 7600. I did this by tapping the Icom's IF port and setting the dongle to the 64.445 IF frequency. Works great.

For rigs not providing access to their IF (that is, without hardware surgery) there are ways of using HF-SDR rigs such as the RFspace SDR-IQ and Perseus as a panadaptor. While these units can work quite well, they are a bit pricey when compared to VHF/UHF dongles. So the question I'm wrestling with is whether a VHF/UHF dongle together with a decent upconverter could be used in place of an SDR-IQ for a panadaptor application. Would this combination present noise from either the dongle or upconverter or present any other limitations?

One device I just discovered is the DXpatrol by CT1FFU (www.ct1ffu.com) that packages the dongle and upconverter into a single device.  I read somewhere that his upconverters have a good track record as well.  At $102 shipped it seems reasonable if it can fit the application.

Thoughts?

Harry WE1X
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NI0Z
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« Reply #1 on: Today at 07:32:12 AM »

Try an Afedri, they are better than the 8 bit dongles (12 Bit), simple to install and use and work really well.  The Diagram below shows a QS1R (16 bit - really good!), however, you can put any SDR in the same setup and get the desired result.

The Afedri review is here and you can also find many other SDR reviews there as well.
https://sdrzone.com/index.php?option=com_content&view=article&id=89:afedrinet-review&catid=20:mosaics&Itemid=572

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K9IUQ
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« Reply #2 on: Today at 08:17:23 AM »

The Diagram below shows a QS1R (16 bit - really good!)

however, you can put any SDR in the same setup and get the desired result.

Thanks to your review article on the QS1R last fall I bought the QS1R. I have been using it in almost your exact configuration with my TS-590s. I use HDSDR software, I prefer it over SDRMAXV. This configuration is invaluable when I try to bust a pileup. In addition I gained a really good  2nd RX with the QS1R.

Also the QS1R is supported by CW Skimmer (Server). When not in a pileup I use the QS1R with CW Skimmer Server to deliver spots to my Commcat Spot Cluster client. The Skimmer software will automatically scan up to 7 bands on the QS1R. This is a VERY powerful setup and has given me many DX contacts I would never had gotten otherwise.

Stan K9IUQ
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WE1X
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« Reply #3 on: Today at 09:07:52 AM »

I've heard great things about the QS1R both as a standalone receiver and panadaptor application. However, it seems really expensive and scarce on the used market. Is it overkill as a panadaptor?
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K9IUQ
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« Reply #4 on: Today at 09:33:14 AM »

I've heard great things about the QS1R both as a standalone receiver and panadaptor application. However, it seems really expensive and scarce on the used market. Is it overkill as a panadaptor?

$900 for a great cutting edge versatile receiver is not expensive. Spending $7000 on a Flexradio IS expensive.

It is not overkill if your knobbed radio does not have a panadapter. Being a Flexradio owner you already realize the advantage of a panadapter. Solutions like those described above can give anyone a panadapter  (and the ability to point n click tune) and as a bonus a very competitive 2nd RX. Using any SDR RX as described gives you the benifit of a knobbed Radio/transmitter and a SDR RX. The best of both worlds. You get most of the advantages of a SDR without the frustrations and promises of the Flexradio company

QS1R's are scarce on the used market because those that own one do not want to get rid of one. Many QS1R's are being used as CW Skimmer Servers. Anyone who has used a Dx Cluster in the last 2 years has benefited from the QS1R.

Stan K9IUQ
« Last Edit: Today at 09:44:31 AM by K9IUQ » Logged
K9IUQ
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Posts: 1757




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« Reply #5 on: Today at 10:03:43 AM »

Perhaps I should explain why the CW Skimmer Server is so powerful for DXers using the CW mode.

CW Skimmer is a program that will work with any Radio but it really shines when used with a SDR. CW Skimmer Server is a separate program that works with the QS1R. It will scan up to 7 hambands of your choice at a time - automatically. It can be set to give you the call of every CW signal in the selected bands OR every CW signal that is sending CQ. Since the QS1R is RXing on your own antennas you know you can copy/work the station. Probably most of the CW Skimmers feeding the internet Dx Clusters are running on a QS1R.

In my situation I do not feed the results of skimming to the internet DX Clusters. Instead I feed the DX calls (via local Telnet) directly to the Spotter Client in my LOgger (Commcat). What this means is any time a CW station calls CQ I get his call immediately in my Spotter Client. Click on the DX call and my TS-590s tunes automatically to the frequency. Many times I get to the station BEFORE he is even done calling CQ. See any advantage here?? Now you understand why the QS1R's are rarely for sale on the used market Cheesy Cheesy

http://www.dxatlas.com/CwSkimmer/
http://www.dxatlas.com/SkimServer/

Stan K9IUQ


« Last Edit: Today at 10:11:53 AM by K9IUQ » Logged
NI0Z
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« Reply #6 on: Today at 10:42:54 AM »

The QS1R review here has some Skimmer information, I love using it along side my other SDRs for real time propagation views from my QTH.

https://sdrzone.com/index.php?option=com_content&view=article&id=86:zone-qs1r-review&catid=20:mosaics&Itemid=572

The thing to keep in mind here with regards to all this is that if your panadaptor SDR is inferior to your main receiver then you don't have a real view of the spectrum.  I found in testing that the 8 bit Dongles, and even the more commercial pricier dongles don't match what the better SDR's can do.

If you just want a pretty display then you can buy something cheap, if you want it to be really useful and also get one of the best Ham Radio experiences one can have, then get an SDR equal to or better than your main receiver.

That said, the QS1R is one of the best values available as far as price performance goes.  The Afedri would be the minimal cheapest route I would be comfortable recommending.

« Last Edit: Today at 10:45:25 AM by NI0Z » Logged

K9IUQ
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« Reply #7 on: Today at 11:20:18 AM »

The thing to keep in mind here with regards to all this is that if your panadaptor SDR is inferior to your main receiver then you don't have a real view of the spectrum.  I found in testing that the 8 bit Dongles, and even the more commercial pricier dongles don't match what the better SDR's can do.

A very good point. In a year of constant use I have come to the conclusion that my QS1R is pretty equal in RX performance compared to my Ts-590s. With one exception. The QS1R has a quieter noise floor and is more pleasant to listen to.

Stan K9IUQ
« Last Edit: Today at 11:23:27 AM by K9IUQ » Logged
WE1X
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Posts: 333




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« Reply #8 on: Today at 02:02:51 PM »

...0Z,

Thanks for the info and the observation about 8-bit dongles.  Contrary to Stanley, you're adding some value to my original question regarding choices to be made between a "true" SDR (e.g., QS1R, Perseus, SDR-IQ) vs a VHF/UHF dongle and an upconverter.  Could provide some examples where an 8-bit dongle/upconverter would fall short vs. a true "SDR" for a panadapter application?  The reason for asking is the Terratec T Stick Plus dongle I'm using with HDSDR as a panadapter for the Icom 7600 seems to be doing okay.

Thanks..Harry WE1X
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NI0Z
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« Reply #9 on: Today at 06:02:35 PM »

...0Z,

Thanks for the info and the observation about 8-bit dongles.  Contrary to Stanley, you're adding some value to my original question regarding choices to be made between a "true" SDR (e.g., QS1R, Perseus, SDR-IQ) vs a VHF/UHF dongle and an upconverter.  Could provide some examples where an 8-bit dongle/upconverter would fall short vs. a true "SDR" for a panadapter application?  The reason for asking is the Terratec T Stick Plus dongle I'm using with HDSDR as a panadapter for the Icom 7600 seems to be doing okay.

Thanks..Harry WE1X

Well, again, if you want a pretty display you can just use the dongle, and so long as your just using it for a display only then you'll see most of your strong signals so in that case you can use the cheapo device.

Let's say though you want to use it as a true second receiver, or use it to help detect weak DX and actually listen to the output, then you get what you pay for and as a second receiver it's worse than the cheapest ICOM you can buy.  You might for example use the 7600 for transmit and the SDR for receive.  BTW, if you try to listen to both at same time on same frequency, your going to have a delay and hence nasty echo problem.  So if your using the SDR as the receiver your listening to and transmitting with the ICOM then your going to have the receive volume off on the ICOM.

You can read the responses here for the technical details, no need for me to reinvent to technical explanation of differences in resolution based on bit depth.

http://ham.stackexchange.com/questions/607/sdr-sampling-bandwidth-do-the-bits-per-sample-matter

Since you have a 7600 with a really good receiver, unless you want to improve upon your receiver either to get something quieter or better reception, then the dongle will be ok as a display only.  If you want a superior receiver then you'll want one of the more expensive SDRs.

The whole debate about whether SDRs are better than traditional Riggs, well, that's not exactly been really quantified with the newer SDRs as you can't do apples to apples testing.  Hence why the new Flex, Anan's ect are not on the receiver charts yet.

In my informal testing using a variable attenuator I give the Anan 100D a slight edge over the KX3, I own both still currently as well as the QS1R and a Ettus B200.

Up converters are lousy though, head to head though the Afedri beat the FunCube Dongle Pro Plus, also owned both those as well as a Flex 5000 which the Anan beat out as well.  Depending on the upconverter you use and or the local interference you have in the upconverter frequency range, you may get stray signals on your display.  Forget up conversion if your really want to use the SDR as a second receiver.  A lousy upconverter makes a great SDR just as lousy as the cheap upconverter.

I have not had my hands on the new Flex Riggs, donut I will but have info that it's no better than the Anan or visa versa.  Both have 16bit ADCs.

So it all comes down to what you really want.

« Last Edit: Today at 06:06:14 PM by NI0Z » Logged

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