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Author Topic: The New RSPdx SDR on Longwave and Mediumwave  (Read 496 times)

K0OD

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The New RSPdx SDR on Longwave and Mediumwave
« on: April 12, 2020, 09:29:09 PM »

Trying new radio equipment is a fine way to use time in the CV-19 Hunker Bunker, so recently I acquired the new RSPdx SDR receiver by RSPlay of England. I've owned two early model RSPs and found them inadequate on longwave due to artifacts and overload from local powerhouse broadcasters. The $199.00 RSPdx which covers 1kHz to 2GHz includes many changes, but it especially improves dynamic range under 2 MHz and it includes filtering that can be switched on to remove RF from above 500 kHz and from the FM broadcast band. RSPdx adds low pass filters at 2MHZ and 500kHz. 

The band button cluster adds several LW bands including 2200 and 630 meters. There are buttons to select two NDB ranges and even the Lowfer experimental band. If you're a LW/MW ham or listener, this is the RSP model for you.

In addition to a basic computer and antenna, you'll need to download SDRUno's free software Version 1.33 or beyond to use the newest features.

Based on a few days of testing, the RSPdx works as advertised in providing strong clean coverage of the longwave spectrum even at my urban QTH. Tuning through RF's basement from 1 kHz to the MW AM broadcast band, I detected no overload or spurious  signals.

Be warned that these feature-rich RSP SDRs are complex. Here's the RSPdx datasheet with more details:  https://www.sdrplay.com/resources/RSPdxDatasheet.pdf

Anyone else learning their way around the RSPdx?
« Last Edit: April 12, 2020, 09:33:53 PM by K0OD »
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VK6HP

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Re: The New RSPdx SDR on Longwave and Mediumwave
« Reply #1 on: April 15, 2020, 08:17:16 PM »

Thanks for posting the information - I had not caught up with the RSPdx update and it's good to see  they've paid more attention to the needs of LF/MF users. 

I use a TS-890S on MW at present, although I'll be migrating the MW station over to a TS-590S in the near future.  Since I'll miss the bandscope of the 890S, I could see the RSPdx being a useful bandscope for the 590S.  I'm also chasing some particularly annoying intermittent QRM on 630m and, without going into detail, need a portable receiver with a good spectrum display.  The RSPdx could be useful there as well, in conjunction with a laptop or similar.

73, Peter.
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AA4HA

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Re: The New RSPdx SDR on Longwave and Mediumwave
« Reply #2 on: May 01, 2020, 12:09:18 PM »

I have an RSPduo attached to a Wellbrook ALA100LN that I added a large (10 meter long) loop to. It is great for monitoring 630m up to around 20m or so. Very sensitive, good figure 8 pattern.

Had to get the antenna well away from the house (50m long coax cable, I live in the woods) and added ferrites to the coax, USB cable and DC power for the Wellbrook DC injector.

Very pleased, about the best LW/MW/SW monitoring receiver I have.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama

VK6HP

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Re: The New RSPdx SDR on Longwave and Mediumwave
« Reply #3 on: May 02, 2020, 08:33:39 PM »

I also find a Wellbrook loop works well and in fact it's been my only receive antenna on 630 m until quite recently.  As Tisha says, it's worth doing dome optimization of the installation and some careful checks on completion: if you're not getting good deep LF/MF nulls, keep going.  Mine is in as good a location as I could find on the suburban block, mounted about a loop diameter above a garden bed.  The RG8X coax is largely underground and, interestingly, I didn't notice any significant improvements as I tried various extra choking and decoupling tricks.  However, that's no doubt a function of the particular installation.

Recently I tried a homebrew 10-turn, tuned, frame loop, with a single turn coupling loop on 630 m.  It's not broadband (well, not without adjustment) like the Wellbrook loop but I've found it's pretty much the equal of the commercial loop around 475 kHz.  I'll probably keep the Wellbrook loop for my main station, and use the 1 m square frame loop for the separated MF station.  That station is built around a rack mounted TS-590S and a homebrew PA; the frame loop can be split between the TS-590S receiver and an SDR as required.

73, Peter.
« Last Edit: May 02, 2020, 08:40:02 PM by VK6HP »
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N0YXB

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Re: The New RSPdx SDR on Longwave and Mediumwave
« Reply #4 on: May 03, 2020, 04:39:15 PM »

Thanks for the post. I have the RSP-1 and RSP-1A, and have been wondering if it's worth obtaining the RSPdx. Looks like here's a RSPdx in my future.  :)
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