Bricked RTL SDR Dongle!?

[natedawg1604]

So, it appears I just fried some component (perhaps the RF circuit?) of my brand new RTL2832U R820T2 dongle (less than a month old) It's my second dongle I've purchased from the RTL SDR blog. For several weeks it worked fine (at Zero PPM no less), I've been using it with Unitrunker along with a second virtually identical dongle (only difference is the newer one has the SMA connector). Since I bought the second dongle I've been monitoring various EDACS and DMR systems with DSD+ Fastlane and Unitrunker. I'm running an HP Compaq (dual boot/w Linux & Windows 7) with a 3 GHz AMD CPU and 4 GHz of Memory, it's kind of old but seems to work fine - it will run OP-25 for weeks without any problems.

So, earlier today while I was listening to a local EDACS system on Unitrunker with a 2-dongle setup, all of the sudden my newer dongle died. It was connected to a Larsen Triband via a short run of RG-58A/U and a magnet antenna mount, mounted indoors. At the time it died it was being used to drive a Voice Receiver in Unitrunker for an 800Mhz EDACS system.

When I tried to use it with SDR#, it recognized the dongle itself, but SDR# was displaying almost no frequencies whatsoever in frequency ranges with dozens of strong active frequencies. So, I'm fairly sure some component of the dongle got fried.

I took the dongle apart and couldn't find anything obviously wrong. Does anyone know why a RTL SDR dongle would die like this? I've been using another RTL2832U R820T2 dongle since March 2015 of this year, and I've left it running for days or even weeks without any problems. I'm going to order a new dongle right away, but I'm concerned about diagnosing why this happened, so I can prevent it's recurrence if possible. Does the RTL2832U R820T2 have an ESD diode (I thought it did)?

Could this be caused by stray voltage coming up a ground wire or something weird like that?

 

[Voyager]

Any close transmitters?

 

[natedawg1604]

Any close transmitters?

I wasn't aware of any, at least not directly adjacent to my house.

EDIT: I just realized, I was recently using an external USB Wifi dongle device with a small antenna for something totally unrelated (It's a TP-Link TL-WN722N); I usually try to only use it when my RTL dongles are unplugged, but in the last few weeks they were sometimes used at the same time in the same room. Maybe that's what did me in here.

 

[Voyager]

WiFi should not be that strong.

Could Windows 7 have updated the driver "for you" to something that is not compatible?

 

[natedawg1604]

WiFi should not be that strong.

Could Windows 7 have updated the driver "for you" to something that is not compatible?

I don't think so; I keep the machine offline most of the time and I have automatic updates disabled, as far as I know. And, I'm not getting any error messages about the dongle not being recognized by Unitrunker or DSD# (i.e. like you would see if you left it unplugged or something).

Also, when I boot-up in Kali Linux, rtl_test recognizes the dongle, and it will run PPM calibration with the -p flag. However, when I try to use the dongle with OP-25 on a strong simulcast site with paperclip reception, it won't lock onto the control channel no matter what the PPM setting, and the spectrum graph shows zero activity on any frequency, just like the graph in SDR#.

Also, just as with the windows programs, OP-25 doesn't raise any errors about the dongle not being recognized. Are there any further tests I could run to make sure the dongle's RF circuit is truly fried?

Also, how close would a cell tower or other LMR site have to be, to fry a dongle? Less than a mile? I wasn't aware of any nearby transmitter interfering with my hardware scanner, but who knows.

 

[Voyager]

It would have to be within about half a mile. Of course, there are no absolutes on that.

I was thinking more if you or a neighbor were a ham and was transmitting.

 

[natedawg1604]

Well I finally got my new dongle, after days of mental anguish while it sat in a UPS truck undelivered due to holiday backlogs or whatever. Anyways, it appears the new dongle also has a Zero PPM, which is pretty cool. I guess I will have to wait and see if the problem re-appears.

Am I correct to assume that the type of interference likely to ruin a dongle's RF circuit, would involve a fairly large antenna mounted outside?

 

[Voyager]

Could be that, or a portable inside near its antenna, or a heavily used Cell or PS site, etc.

Basically anything that would provide a full scale signal could cause damage.