Search found 15 matches

by Stromeko
Wed Jul 17, 2019 6:39 pm
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

You might take solace in the fact that not even the RaspberryPi folks got USB-C power delivery right and then didn't catch it in pre-manufacturing testing either:

https://hackaday.com/2019/07/16/explori ... -in-depth/

:roll:
by Stromeko
Tue Jul 16, 2019 5:50 pm
Forum: KerberosSDR
Topic: Strange USB problems
Replies: 4
Views: 1186

Re: Strange USB problems

If you power the unit via USB-C, then there shouldn't be any appreciable voltage drop on the USB connection to the PC. If you specifically bought a "long USB cable with low voltage drop", then chances are it's meant for charging only and has never been tested with actual high-speed USB communication...
by Stromeko
Wed Jun 19, 2019 8:09 pm
Forum: KerberosSDR
Topic: Bias-T on KerberosSDR?
Replies: 3
Views: 1206

Re: Bias-T on KerberosSDR?

OK, so are the antenna inputs decoupled or do I need to protect them from DC on the coax?

Just asking, I guess I'll go for an LNA (or rather four of them) that has an external bias input and feed the power to the LNA via a separate line.
by Stromeko
Sun Jun 16, 2019 11:10 am
Forum: KerberosSDR
Topic: Bias-T on KerberosSDR?
Replies: 3
Views: 1206

Bias-T on KerberosSDR?

Does the KerberosSDR have a Bias-T like the V3 dongle? If so, are these independently available on all antenna ports?
by Stromeko
Sun Jun 16, 2019 11:07 am
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

The USB-C PSU (captive cable) showed up yesterday in the mail and I'm happy to report that it also works with the KerberosSDR. I specifically selected one that was having variants with different connectors (barrel and micro-USB) available on the assumption that it would be a "dumb" PSU and not pay a...
by Stromeko
Wed Jun 12, 2019 6:32 pm
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

First verified working option for powering the KerberosSDR via USB-C: a PSU meant for the rasPi 3B+ (3A fine-tuned to 5.1V output) and a passive adapter from microUSB (2.0) receptable to USB-C plug. Even though the adapter is really tiny, mechanically a short cable would work better, but I didn't fi...
by Stromeko
Sat Jun 01, 2019 4:01 pm
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

Is there a documentation of the GPIO connector on the board and can the Kerberos be powered through that?
by Stromeko
Sat Jun 01, 2019 3:54 pm
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

The amperage on the PSU is only a tangential indicator of how good the regulation is under higher load. The problem really is that the Pi needs a stable voltage and the resistance in the supply will create a large enough voltage drop to make it unhappy if the unloaded voltage (at the PSU end) starts...
by Stromeko
Fri May 24, 2019 6:36 pm
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

USB-A doesn't (officially) allow for 3A, so most PSU only supply a maximum of 2.4A per port (I have a bunch of those). The obvious non-USB option would have been a barrel plug, but I recognize that these may be more difficult to fit onto the board unless you're going to solder them separately. Again...
by Stromeko
Wed May 22, 2019 7:35 pm
Forum: KerberosSDR
Topic: Power connection question
Replies: 25
Views: 4736

Re: Power connection question

OK, that reply confirms my suspicion. Please have them read the USB spec to come up with a spec compliant way to do a power sink with a USB-C connector. Again, you need pull-down resistors there, not pull-up. So in summary the only option of powering through this connector is to try and get a non-co...