[time-nuts] Re: Ublox LEA-4T mentioned here. Have fired one up

[John Miller]

Hi Paul,
Thanks for sharing this info! I ordered one of these lots as well, and it should arrive today, actually. My intention is to re-mount the modules on more sensible breakout boards, maybe a Pi Hat. 

The 8 pin chip on the board is an MCL BP2G. RF power combiner/splitter https://www.minicircuits.com/pdfs/BP2G+.pdf <https://www.minicircuits.com/pdfs/BP2G+.pdf>

If I am reading the datasheet and board layout right, the top connector is connected to PORT1, the GPS is PORT2, and the side connector is SUM. I would imagine that the GPS would be on SUM if the idea was to feed in >1 RF signal, but maybe I am misunderstanding it?

I was surprised by your note that the USB voltage input is 3v, but after checking the LEA-4x datasheet, sure enough, 3.6v max. I thought all USB had to be 5v?

Finally, it looks like the PCB is ceramic, rather than normal epoxy/fiberglass. Hopefully that doesn't make removing the modules any more difficult...

John

> On Apr 5, 2022, at 9:14 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Hello to the group.
> Gregory had mentioned a deal on Ebay for 5 X LEA-4T receivers at $25.
> Seemed like an OK deal to be able to have a few units around for
> experimenting.
> They arrived and were easy to get operational.
> They are a little different. The module actually has 2 antenna inputs. Took
> a bit to figure out what was going on. Both work in the L1 band and the
> side connector appears more sensitive by 4-5 db. But both work.
> Its a circa 2006 16 channel receiver and does capture WAAS.
> Locks in about 30 second from cold start. Ublox u-center 8.18 works fine
> with the unit.
> Its setup for USB. But that USB is just 3V logic so be careful.
> The unit runs on 3V. None of the ttl 3V rs 232 ports connect to anything.
> But TX1/RX1 actually have control and data at 9600 baud. Pins 3-4 on the
> actual chip. Attaching some small wires allowed complete control of the
> module after passing through a logic to usb serial converter.
> 1 PPS works just fine but have not compared it to anything.
> So for me at least the $5 wonders will be fine.
> Regards
> Paul
> WB8TSL
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