I tried both:
1. bringing 5V to the coax connector requires a very long wire from the 
USB connector going all the way along the RF components of the DVB-T dongle: 
I found this wire to act as an antenna and significantly degrade the 
performance 
of my dongle 
2. I made a small PCB including a 10 nF capacitor (0.02 ohm impedance at
1.575 GHz) and a 1 uH (50 kohms impendance at 1.575 GHz) going to the +5V
pin of a USB-B connector. Seems to work properly, though I am still truggling
to make sure I am indeed getting a GPS signal. The components were picked from
some leftovers so the actual values you select my differ.

JM

> I would like to connect an active GPS antenna (5v) to rtl-sdr.  Here is I 
> thought:
> 
> 1. Modify board let power go through the board MCX
> 2. Buy a bias T. But I want power the bias T with my laptop, is there any USB 
> power bias T type of device in tHe market?
> 
> Other solutions?
> 
> Thanks
> Dan
> 
> Sent from my iPad


-- 
JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 32 av. observatoire, 25044 
Besancon, France

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