RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

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Robert11
Posts: 81
Joined: Fri Sep 28, 2018 12:00 pm

RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by Robert11 » Wed Jul 24, 2019 10:45 am

Hello,

Have a RSP-2. Great product.

I have a NooElec 1:9 Balun, and am using a single long wire receive
only antenna outside for the <30 MHz listening.

There is a coax run from the end of the long wire into the house, and into the NooElec Balun..

I'll play around with it of course, but was wondering from
a "theoretical" view, what is the recommended setup ?

I have the two twisted wires from the NooElec output going to the P and N terminals of the HiZ input.(green connector on the RSP-2)

Question: Should the Gnd connection on this green connector be grounded ?
To what ? Or, just leave floating ?

The sketches I've seen always seem to show it floating.

Thanks,
Bob
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glovisol
Posts: 662
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by glovisol » Wed Jul 24, 2019 12:38 pm

Dear Robert 11, if you read this thread:

https://www.sdrplay.com/community/viewt ... f=8&t=4493

and this:

https://www.sdrplay.com/community/viewt ... easurement

Of course you will need a lot of patience, as they are long threads, but then a clear picture will unfold under your eyes. The picture you will see will essentially shows you this:

1) That the HI Z input of the RSP receiver is the most sensitive and with the best ability to reject noise: by noise I mean man made noise which is all around you.
2) That to best reject man made noise you should use the simplest configuration, e.g. going in reverse from the RSP HI Z to the antenna: low noise ferrite toroid transformer, as described in the references above and in many of my posts - Long wire lead to one primary lead of the transformer and counterweight lead to the other primary lead. If you cannot do without the coax, then you have to experiment with the grounding and/or bottle chokes.
3) You can try and connect a ground (stake ground) to the ground input of the RSP, but most of times it will bring noise in. You must regard stake ground as useful only for human safety purposes and nothing else, as it is the Troian Horse that brings noise in.

Much more you will learn just by patiently reading the treasure of information this Forum has accumulated already, rather than asking questions: the answers are there already for you!

Kind regards,

glovisol
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mikeladd
Posts: 189
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Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by mikeladd » Wed Jul 24, 2019 3:59 pm

I recommend that you join the SDRplay FB group. One user "Roger Need" posted an in-depth thread on using the 9:1 with the RSP.
If you decide to join the independent SDRplay group, the thread is located here.
https://www.facebook.com/groups/sdrplay ... 511653934/

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SDRguy22
Posts: 12
Joined: Fri Jul 19, 2019 4:34 pm

Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by SDRguy22 » Wed Jul 24, 2019 4:18 pm

Robert11 wrote:
I have the two twisted wires from the NooElec output going to the P and N terminals of the HiZ input.(green connector on the RSP-2)

Question: Should the Gnd connection on this green connector be grounded ?
To what ? Or, just leave floating ?

The sketches I've seen always seem to show it floating.

Thanks,
Bob
Bob,

SDRplay has published a User guide on how to connect to the HiZ port. You can find it here:

https://www.sdrplay.com/wp-content/uplo ... uidev2.pdf

If you want to use an off-the-shelf balun the NooElec is a great product for use with an RSP2 or RSPduo HiZ port. My own preference is not to use twisted pair because they can pickup RFI in your shack. Instead I use a couple of short wires so that the NooElec device is located right at the green block of the RSP.

A ground connection to the RSP green block may or may not be helpful. This ground connection is also attached to the USB shield ground so there is a connection to the ground of your computer. Attaching the green connector to another ground point may create a ground loop and you will pickup even more noise. I leave mine disconnected but you might get different results depending on your computer setup, local AC grounding and whether you have a proper RF ground in your radio room. Just try experimenting and measure the noise level at different frequencies.

There have been quite a few recent discussions on how to connect to the RSP HiZ port on the SDRplay Facebook page. One contributor there suggested cutting the track on the back of the NooElec for lower noise pickup and this was verified to improve things by several other posters. Other suggestions for the NooElec with HiZ antennas have also been proposed. I suggest you join this Facebook group. It is very friendly and there are over 10,000 members so you usually get an answer in a few minutes. There is also a SDRuno Facebook page which helps solve software questions.

Bill
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sdrom33
Posts: 128
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Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by sdrom33 » Wed Jul 24, 2019 6:12 pm

Hi Mikeladd, the thread address you uploaded does not work, pse check, thank
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mikeladd
Posts: 189
Joined: Wed Jul 08, 2015 3:18 am

Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by mikeladd » Wed Jul 24, 2019 6:47 pm

The link works on me end. I just tried it again.
https://imgur.com/eI9pcwp

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sdrom33
Posts: 128
Joined: Sun Dec 09, 2018 4:38 pm

Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by sdrom33 » Wed Jul 24, 2019 7:00 pm

Sorry, mikeladd, I do not understand, this last link is different from the first you gave me & it is not a workgroup....can you help/explain?
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mikeladd
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Re: RSP-2 HiZ Input Question: 1:9 Balun and Grounding ?

Post by mikeladd » Wed Jul 24, 2019 8:46 pm

You need to join the Facebook group for the link I posted originally to be valid. It is a closed group so the link I posted will not be valid outside of non members.

"If you decide to join the independent SDRplay group, the thread is located here."
https://www.facebook.com/groups/sdrplay ... 511653934/

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