iMONITOR
Silent Key
Anyone using longer USB cables so they can use shorter coax antenna cables to reduce loss for their SDR's? If so, how long of a USB cable were you able to get away with? Any pro's or con's to doing this?
Longer USB Cables = Shorter Coax Cables?
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I've done it for some indoor (in attic sdr's). All pro, no cons at least indoor. I was running about 25 or 30 feet by daisy chaining 2 amplified usb cables. Worked fine for a flight feeder. Outdoors, I haven't tried it, in part because I suspect most if not all usb cables I'm likely to encounter won't stand up well to the elements.
Note, that I've only done this with cheap dongles that I don't mind roasting in the attic; surprisingly, they all survived.
Note, that I've only done this with cheap dongles that I don't mind roasting in the attic; surprisingly, they all survived.
cellphone
Silent key.
I used a powered USB extender and have two in the attic. I set this up about 2 years ago. My only complaint is that the SDRs are a little noisy and affect the noise floor for other antennas in the attic. They are only noisy when running, so I stop them if the noise is causing issues for my other radios. Give it a try. They work great for me in the attic connected directly to good antennas.
My run is 75 feet and the extender uses Cat 5 Ethernet. I think you can go up to about 200 feet max with a powered extender. They are also in the Phoenix heat and still functioning!
My run is 75 feet and the extender uses Cat 5 Ethernet. I think you can go up to about 200 feet max with a powered extender. They are also in the Phoenix heat and still functioning!
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msingewald
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I put the whole PC with the SDR's in the attic then use Anydesk to remote in.
iMONITOR
Silent Key
I did something similar with a Uniden BCT15X a couple years ago. I put it on the second floor, on a high closet shelf. It gave me a good height advantage for aircraft and it worked great! I used TeamViewer to control it.
The SDRplay devices would do well in the attic as they don't get real hot like the RTL-SDR's do. For really high frequency exploration I was even considering mounting an SDR in a NEMA 4 outdoor weatherproof enclosure. It would be real easy to heat it internally during winter months. Not sure if there would be a way to cool it during the summer if needed. Possibly a thermoelectric Peltier Cold Plate would do the job. The entire rig would be small enough to mount directly on the antenna mast keeping coax to an absolute minimum to prevent loss.
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Has anyone tried bonding the newer metal-cased RTL-SDR.com dongles to a suitably-sized heat sink, maybe with two L-brackets (one at each end) and some thermal transfer compound also between the case and sink? Is there a way of knowing how hot it's running, other than maybe adding an internal thermistor, feed-thru cap, etc.? Like a transmitter PA, we don't really have to get it to room temp, just to somewhere within the spec'd operating temp of the components, which could be 100+ (F), right?
If you cant hold your hand on it indefinitely, it is too hot. I use a C-clamp and small heatsink.
Try about 5 turns through a ferrite core at each end of the cabling.
That would take an un-needed computer that way. My BCT15X is over in the corner, USB and proscan for control.
Discriminator tap to an amp for decoding. Audio is the PC
cellphone
Silent key.
My problem is not noise on the USB line for the SDRs. When the SDRs are running, they produce noise that is picked up by other antennas in the attic. The other antennas feed down to radios in my shack with LMR-400. Are you recommending ferrite cores on the LMR-400 feed line?
Been considering getting a Pi4, using PoE for that, with dongles for ADSB feed, and putting that all inside a plastic enclosure.
iMONITOR
Silent Key
Keep us updated on your progress. Sounds interesting!
Incredibly inefficient, limited by ambient air temps & uses gobs of power.
iMONITOR
Silent Key
You're right. I was shock by the current draw of these devices.
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