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

[paul swed]

John indeed on the 3V. I have lots of 3.3V regs. Not sure I have a 3. But
like you I am thinking the same only maybe simpler. Simply solder it to a
piece of copper board thats larger so I can mount interface chips drill
holes for screws and such. Also some standoffs for 1pps, ext in/out, rs232
tx1/rx1. Smaller wires are the way to go on connecting to the pins. At 3V
startup is 65ma settles to 57ma. The input is a bit odd. Like you I spotted
the mcl combiner/splitter. The side port is 4-5 db hotter than the top
port. But both work. So its a bit odd as if it was intended for 2 antennas.
Kind of doesn't really matter as its totally working on the TX1/RX1 port. I
set it to 115200 baud. It comes up 9600. That change is sort of silly.
Thinking about mounting the board on the copper board component side down.
Easy to solder copper support wires then. No screw holes kind of a pain.
While soldering I have a small tip iron and found it really needs to be at
700 F or so to do good job.
On one of my units and in the ebay pix there is a spot of tape that holds
down I assume a small regulator and TCXO. But it really doesn't seem to do
anything. Four of my units do not have that mod. So have not really figured
it out yet.
Good luck.
Paul

On Wed, Apr 6, 2022 at 12:51 PM John Miller via time-nuts <
time-nuts at lists.febo.com> wrote:

> 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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