I have defective BiasT with my RTLSDR V4 which i have purchased some weeks ago. I have already the chip which controls the BiasT. Voltage arrives with 3.3V and 5V but the chip with the label 42ml is not providing any voltage when BiasT is enabled in the software. Receiving is still OK. So i think this chip is defect and i want to repair my RTLSDR V4 but i can not find the type of the chip and where to get one! Is there some help possible?
I also have a HackRF One Portapak H4M. Also purchased some weeks ago. Here i have the problem that no signal is going through. I think that the chip labled SKY13317 is defect as when i switch on BiasT this is OK and delivers 3.3V. But when ich switch RF Amp on nothing happens. Where can i get such a chip so that i can repair my HackRF?
My problem is that i can find the SKY13317 but it is not the right pakage form! So i am confused as when i load the KiCad files there is mentioned the SKY13317 but the pakage is different to that what i can buy.
And for the replacment chip on the RTLSDR V4 i can not find any chip to buy. It disgusting!
the SKY13317 is available in only one variant: SKY13317-373LF and, as far as I can see from the Datahseet and HackRF kicad_pcb file, the footprint matches (1.5x1.5 QFN-8 w/ exposed pad, 0.4mm lead spacing, Sky calls this “MLP”).
I don’t think the RTL-SDR design files are open source, but maybe @rtlsdrblog has a BOM and can look up that part?
Thank you for the advice. I meassured the chip and you are completly right it is the 1,5x1,5mm form. When i look at the board the SKY13317 looks like another pakage but it is the QFN-8! I all ready ordered some from Aliexpress and will have a look if my hot air station can do the job on the HackRF R10. But a small chance is better than throwing away!
For the RTLSDR i now have written an e-mail to the RTLSDR admin and hope to get the right information. If not i will meassure the resistor and have to sort out the correct chip. If not there are plenty of alternatives and somewhere i have a stack of SMD resistors. Worst case i will have to switch the chip and the resistor, too. In the end i have to limit the current to 150mA as advertised by RTLSDR.
You can replace the bias tee LDO with an LP5907 which is pin compatible.
But if it’s faulty, and it wasn’t your fault, as in it was a manufacturing defect and not due to some external damage event, we would just replace it for you. Email admin@rtl-sdr.com with order details.
I would have bet on a LDO which can be regulated by a resistor ;-).
I will try the LP5907MFX-4.5!
And i have destroyed it by applying 12V with an external bias tee by accident. Put the false cable onto my RTLSDR and my HackRF one… What a pitty. But glad that the RTLSDR is still working and now im confident that the bias tee will come back!
For your information. Today the chip arrived and i have resoldered the LP5907MFX-4.5. Works like a charm. A little bit fuss with the lead free solder but then all OK! That was fun!