uBlox GPS control

[VK3ALB]

Hi All,

I'd like to hear from anyone that has experimented with uBlox u-center and specifically with making changes in UBX-CFG-ANT. I have some GPS modules that do not provide VCC_RF out of the box. This means VCC_RF should be there according to u-center but it is missing hence no supply for external antennas.

This is the circuit.

I lifted R5 and fed 3v3 in from another part of the circuit to get a supply to the antenna. Strange thing is, when I re-powered the board in this configuration VCC_RF returned. Yes, I thought perhaps there was some funny load condition on power up that causes VCC_RF to be shut off but that is not the case because it's not enough to simply disconnect R5. VCC_RF only came back once I connected supply to the external antenna.

Finally, has anyone made u-center switch VCC_RF on/off?

[VK3ALB]

Update:

Internal DC path between pin 9 & pin 11 is around one ohm. What I'm measuring is the supply voltage provided by L1 (after modification) coming back in through pin 11 & showing up on pin 9. Still no luck in enabling VCC_RF via u-center control.

[VK3ALB]

Final update

The chip is probably real but the block is probably a fake. I visited someone with a microscope and we took a closer look inside.

It looks like pin 9 simply connects to pin 11 via a choke. The place that I "think" VCC_RF comes from is a poorly formed pcb via which is bypassed to ground by the black component. It does not connect to anything else.

I believe that the green board is a knock-off Chinese copy of an original uBlox and the PCB design is flawed. You can see nearby some shonky track layouts and the fact that there is no other connection to pin 9 confirms my thinking.

In any case, the block simply doesn't look like a real uBlox item.