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Author Topic: RTL SDR with one antenna  (Read 2346 times)

Offline bigscott55

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RTL SDR with one antenna
« on: April 21, 2017, 07:13:49 PM »
How would i go about hooking up 2 SDRs to one antenna?  splitter?  would that affect my gain etc?

Scott



Offline dave

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Re: RTL SDR with one antenna
« Reply #1 on: April 21, 2017, 07:50:22 PM »
You would typically use a 2-way splitter...you would lose about 3dB on each receiver (half the signal power).

To avoid the splitter loss you could use a preamp with just enough gain at its output to overcome the splitter loss. Most preamps have a lot more gain than 3dB so you would want to pad down (attenuate) the output of the preamp a bit.

Offline bigscott55

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Re: RTL SDR with one antenna
« Reply #2 on: April 22, 2017, 01:09:04 AM »
would something like this work?  https://goo.gl/N9zghq

Offline dave

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Re: RTL SDR with one antenna
« Reply #3 on: April 22, 2017, 07:52:47 AM »
Yes...but the excess gain (+27dB excess) is not going to improves things. It will amplify both signals and noise. I would recommend a 20dB attenuator in line with the output of that preamp. Also, if you live very close to an FM radio transmitter you will want an FM trap filter somewhere inline.

This preamp has an FM notch filter built-in and only 16dB of gain:
http://www.ebay.com/itm/112352540518

so you would have 13dB of excess gain after the splitter. I would recommend a 5 or 10dB attenuator in that case.

You can try it without an attenuator to see if it meets your needs.

If you want a preamp focused solely on 118-136MHz, this one will work well:
http://ebay.to/2oeYsqV

Hope this helps.

-Dave



« Last Edit: April 22, 2017, 07:56:31 AM by dave »

Offline bigscott55

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Re: RTL SDR with one antenna
« Reply #4 on: April 22, 2017, 01:04:32 PM »
man those dongles get HOT!!

Offline dave

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Re: RTL SDR with one antenna
« Reply #5 on: April 23, 2017, 08:32:41 AM »
man those dongles get HOT!!

Yes, they do....but they're built to handle it. If you have them in an already warm/hot environment, coming up with some sort of cooling and/or heat sink arrangement is not a bad idea.