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RTL-SDR V3 long wire problems (SOLVED)

Posted: Mon Dec 10, 2018 4:02 am
by RCND
Hi All;

I have a RTL-SDR V3 Dongle. I just put a 9:1 blun, plus a long wire on it and am now getting many Shortwave stations.

I can receive for about 20 or so minutes, then the bottom drops out. The noise floor goes from -70 to -95 dB and my signals go from -30+ to almost nothing. If signal is strong enough I can barely still hear it.

After closing the program and unplugging the Dongle and waiting a bit, everything works fine for a while and then the same thing happens.

The Dongle does not get hot, which is funny because before I had the long wire I was using just a dipole I got from RTL-SDR.com. The dongle would get very warm with this setup listening to local FM stations.

It seems like the front end is going away with the long wire setup.

This happens in both GQRX and CubicSDR .

Any suggestions would be appreciated.

Robert

Re: RTL-SDR V3 long wire problems

Posted: Mon Dec 10, 2018 9:47 am
by rtlsdrblog
Could there be ESD building up on the long wire? ESD can sometimes push the HF amplifier into problem mode where it stops working until power cycled.

Re: RTL-SDR V3 long wire problems

Posted: Mon Dec 10, 2018 5:54 pm
by RCND
Hello rtlsdrblog:

My current temp and humidity is 36* F and 61 %. There is zero wind. I am still getting the same problem.

I don't think the above conditions are too good for ESD.

Do you know of a way I can measure for static build up on the long wire?

Thank You
Robert

Re: RTL-SDR V3 long wire problems

Posted: Mon Dec 10, 2018 9:35 pm
by tim_rtd
If you can , go out and touch the antenna bare wire with your hand then go and check reception.

Re: RTL-SDR V3 long wire problems

Posted: Tue Dec 11, 2018 4:36 am
by rtlsdrblog
RCND wrote:
Mon Dec 10, 2018 5:54 pm
Hello rtlsdrblog:

My current temp and humidity is 36* F and 61 %. There is zero wind. I am still getting the same problem.

I don't think the above conditions are too good for ESD.

Do you know of a way I can measure for static build up on the long wire?

Thank You
Robert
Contact us at [email protected]. I'll send you another dongle to test with just in case it's a hardware issue.

Re: RTL-SDR V3 long wire problems

Posted: Wed Dec 12, 2018 12:10 am
by RCND
Hello rtlsdrblog:

I just sent you an e-mail with name and address.

Thank you.
Robert

Re: RTL-SDR V3 long wire problems

Posted: Sun Dec 16, 2018 7:30 pm
by hotpaw2
Try putting a 1 MegaOhm resistor between the long wire antenna and a good Earth ground.

Re: RTL-SDR V3 long wire problems

Posted: Sun Dec 16, 2018 8:12 pm
by RCND
Hello hotpaw2:

Thank you for the reply. I will try the resistor trick.

The funny thing is I just received a dongle with a built in upconverter and have been using it since Thursday with out any problems.

I think my V3 just has a problem in the front end.

Thanks again.
Robert

Added on edit: I am using the NooEelec 1:9 Balun. The schematic for this shows a resistor on the center tap of the antenna side to ground. I'm pretty sure it is doing the same as your suggestion.

Added on later edit: After e-mailing Nooelec, they Do Not add the resistor shown on their schematic.

Re: RTL-SDR V3 long wire problems (SOLVED)

Posted: Sun Dec 23, 2018 6:17 pm
by RCND
RTL-SDR.com Sent me a replacement even though I had purchased the old one back in April.

This is a Company that stands behind it's products.

BTW problem solved.

Robert

long wire problems

Posted: Sun Dec 30, 2018 9:42 am
by snn47
RCND and all
It is interesting to note that the NooEelec 1:9 Balun claims to be with Antenna Input Protection, which if true should have protected your dongle. Does anyone have a scrematic or type list of the protection components used? From the picture on amazon I asume that they just used a resistor.

Sufficiently high static electricity takes only a few nano seconds of peak voltage to damage the semiconducters in a receiver.

From experience even prior to the first lightning bolts, sparks were continiously between the inner conductor of RG-213 coax cable several centimeter to the stone bottom below the roof. The antenna was just a small 10 m 1/4 wave groundplane, much shorter than what a long wire will pick up.