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

[paul swed]

John
if you have the mall board taped on its a 3.5V reg ncp600 to feed the side
antenna port.
Its input voltage comes from free pin 3.

On Wed, Apr 6, 2022 at 1:09 PM paul swed <paulswedb at gmail.com> wrote:

> 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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