Since the proposed board is not too dense you can provide the pads
for the SMA connector and driver circuitry and don't populate them
if you don't need that feature. But this is the time-nuts group so I
think that a lot of people would be interested in the PPS output.
Why would you get a uBlox "T" device if not for the timing?
Pete.
On 12/12/2020 12:12 PM, Bob kb8tq wrote:
Hi
The issue with coax becomes:
Do you want to drive a terminated line?
On a board built for a single application, you likely know the answer to that
and can
design appropriately. On a general purpose board, you probably need to allow for
the “worst case” configuration ( = terminated). No, that’s not a recommendation
that
one operate that way, only a recognition that a lot of people *do* operate that
way.
Bob
On Dec 12, 2020, at 11:59 AM, Matthias Welwarsky <[email protected]> wrote:
On Samstag, 12. Dezember 2020 14:40:11 CET Bob kb8tq wrote:
Hi
If you are going to drive much with the timepulse output, you will need to
buffer it. This is true for just about any practical length of coax. It also
applies to other cables once they get past the “few inches” range.
Ideally the coax buffer would be something like 4 or so ‘125 buffers in
parallel, each with a 200 ohm resistor in series with their output. Is it
going to put out 3.3V or 5V logic? ….
A HCT125 should have 3.3V logic compatible inputs and TTL outputs. There are
nice dual-instance buffers available, 74AHCT2G125 for example. But this is not
"breakout board" material any more.
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