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Dongle RTL-SDR very hot

Posted: Sat Sep 14, 2019 10:06 pm
by Ademir
I have read some comments about overheating on the SDR dongle. In my case, I notice this when I use closed-frame antennas such as cubical quad, QFH and the like. In Yagi antennas - open frame - this does not happen. The SDR sees this as a possible short circuit. Any ideas on how to solve? Any filters?

Re: Dongle RTL-SDR very hot

Posted: Sun Sep 15, 2019 6:54 am
by alanzfq
What dongle? Does it have a bias tee? Is it switched on?
That would explain.
Alan

Re: Dongle RTL-SDR very hot

Posted: Mon Sep 16, 2019 2:41 am
by Ademir
Excuse me. My device is a Nooelec NESDR SmarTee and I connect to use SDR # or SDR Console. The heating problem only happens when I use the above mentioned antennas. I do not use any other device connected to Nooelec. Should I change some settings in SDR # or SDR Console?

Re: Dongle RTL-SDR very hot

Posted: Mon Sep 16, 2019 4:35 am
by rtlsdrblog
Ademir wrote:
Mon Sep 16, 2019 2:41 am
Excuse me. My device is a Nooelec NESDR SmarTee and I connect to use SDR # or SDR Console. The heating problem only happens when I use the above mentioned antennas. I do not use any other device connected to Nooelec. Should I change some settings in SDR # or SDR Console?
The problem is that you have a Nooelec NESDR SmarTee. The SmarTee is their RTL-SDR model that has an ALWAYS ON bias tee. Your quad, QFH etc antennas are electrically DC short circuits.

So when you connect your SmarTee to a DC short circuit antenna, you're short circuiting the bias tee inside the RTL-SDR. I believe that they use a thermal fuse to protect against short circuits. But when a thermal fuse trips, it is still drawing some current and generating heat. Over long term use you are probably damaging your thermal fuse, and the bias tee circuit.

Solution: Get a dongle with a software selectable bias tee (like our RTL-SDR Blog V3), or get a dongle without a bias tee if you don't need it, or get a DC block component (capacitor) on the coax line.