[time-nuts] Ebay Huawei Ublox M8T Modules Warning

[Matthias Welwarsky]

Hi,

On Montag, 11. Januar 2021 23:32:24 CET Nigel gm8pzr via time-nuts wrote:
> Noticed Bluegirls changing her listing based on Nigel's false information.

Well, the change to the power supply voltage is certainly correct. The antenna 
supply rating is at least safe now. It might be OK to feed 5V there, but 
that's hard to say without having traced out the circuit. There is no external 
DC block on the PCB (see figure 10 in the LEA-M8 HIM) but that requirement 
seems to be due to V_ANT being connected to GND. That's clearly not the case 
here. There's another variant of active antenna circuit in figure 12, but here 
the supply voltage is fed through V_ANT, which is not what's implemented on 
this breakout board. So it _might_ be OK to feed 5V for antenna bias but not 
sure.

Btw the same PCB shows up in other listings in their shop, with a LEA-5T and a 
LEA-6T. 

> 
> 
> 
> Hmmmmm.... Really?
> 
> 
> 
> Please help me understand what false information I'm supposed to have
> provided?
> 
> 
> 
> I've explained to the seller that the supply voltage should be quoted as a
> nominal 3.3V, with a maximum of 3.6V,
> 
> and that the antenna supply is recommended to be up to 5V with a maximum of
> 6V.
> 
> Ok, so the data sheet actually specifies the Antenna voltage range operating
> range 2.7 to 5.5V, but I was trying
> 
> to keep it simple.
> 
> 
> 
> Unfortunately it seems that the connection data supplied by this and other
> sellers is based on stock images,
> 
> either you get the incorect original showing two 5V supplies, or the current
> alternative showing two 3.3V supplies.
> 
> The current image may not be telling the whole story but, as I commented
> earlier, at least it's playing it safe.
> 
> Beyond that I guess it's back to RTFM as always!
> 
> 
> 
> Nigel, GM8PZR
> 
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