Empathy List Archives

MI

Mike Ingle

Fri, Apr 3, 2020 12:35 PM

Hello fellow nuts,

I just received my PRS-10 with boardlet and heat sink, and I have a
question regarding my PPS output signal.
My output looks strange, (but usable). I have attached a couple
screen-shots of my scope/
The first is with 50 ohm termination after 5foot of 5g-58 cable, the second
is without termination.

--mike
[image: pps_term.png]
[image: pps_unterm.png]

Hello fellow nuts, I just received my PRS-10 with boardlet and heat sink, and I have a question regarding my PPS output signal. My output looks strange, (but usable). I have attached a couple screen-shots of my scope/ The first is with 50 ohm termination after 5foot of 5g-58 cable, the second is without termination. --mike [image: pps_term.png] [image: pps_unterm.png]

BK

Bob kb8tq

Fri, Apr 3, 2020 7:48 PM

Hi

At least according to page 20 in:

https://www.thinksrs.com/downloads/pdfs/manuals/PRS10m.pdf

the “raw” PPS output from the PRS-10 is just a CMOS gate output.
There is nothing suggesting it is designed to drive a 50 ohm load
or a coax cable.

Page 59 suggests that the “boardlet” does nothing but pass the
signal to the connector on the board.

Best guess: It’s doing what it’s supposed to, but not quite what
you expected it to do.

Bob

On Apr 3, 2020, at 8:35 AM, Mike Ingle finndmike62@gmail.com wrote:

Hello fellow nuts,

I just received my PRS-10 with boardlet and heat sink, and I have a
question regarding my PPS output signal.
My output looks strange, (but usable). I have attached a couple
screen-shots of my scope/
The first is with 50 ohm termination after 5foot of 5g-58 cable, the second
is without termination.

--mike
[image: pps_term.png]
[image: pps_unterm.png]
<pps_term.png><pps_unterm.png>_______________________________________________
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To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Hi At least according to page 20 in: https://www.thinksrs.com/downloads/pdfs/manuals/PRS10m.pdf the “raw” PPS output from the PRS-10 is just a CMOS gate output. There is nothing suggesting it is designed to drive a 50 ohm load or a coax cable. Page 59 suggests that the “boardlet” does nothing but pass the signal to the connector on the board. Best guess: It’s doing what it’s supposed to, but not quite what you expected it to do. Bob > On Apr 3, 2020, at 8:35 AM, Mike Ingle <finndmike62@gmail.com> wrote: > > Hello fellow nuts, > > I just received my PRS-10 with boardlet and heat sink, and I have a > question regarding my PPS output signal. > My output looks strange, (but usable). I have attached a couple > screen-shots of my scope/ > The first is with 50 ohm termination after 5foot of 5g-58 cable, the second > is without termination. > > --mike > [image: pps_term.png] > [image: pps_unterm.png] > <pps_term.png><pps_unterm.png>_______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

TK

Taka Kamiya

Fri, Apr 3, 2020 8:27 PM

I've seen this with my own. You are catching the leading edge of ringing of the signal.

Since the output is CMOS, and high impedance, it really doesn't have enough current to push through low impedance cables. Try shorter and different cable. Terminate it with 50 ohms. Set the trigger level little higher. In my setup, the cable is actually a very short twisted pair, and only 2" long into a buffer board.

You might want to look at what your PRS-10 is set to, as far as pulse width is concerned. Also, use much longer horizontal scan rate. The standard pulse width is 10 MICRO second. Your image is capturing beginning of the pulse but not the whole of it.

(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG

On Friday, April 3, 2020, 3:21:09 PM EDT, Mike Ingle <finndmike62@gmail.com> wrote:

Hello fellow nuts,

I just received my PRS-10 with boardlet and heat sink, and I have a
question regarding my PPS output signal.
My output looks strange, (but usable). I have attached a couple
screen-shots of my scope/
The first is with 50 ohm termination after 5foot of 5g-58 cable, the second
is without termination.

--mike
[image: pps_term.png]
[image: pps_unterm.png]

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

I've seen this with my own. You are catching the leading edge of ringing of the signal. Since the output is CMOS, and high impedance, it really doesn't have enough current to push through low impedance cables. Try shorter and different cable. Terminate it with 50 ohms. Set the trigger level little higher. In my setup, the cable is actually a very short twisted pair, and only 2" long into a buffer board. You might want to look at what your PRS-10 is set to, as far as pulse width is concerned. Also, use much longer horizontal scan rate. The standard pulse width is 10 MICRO second. Your image is capturing beginning of the pulse but not the whole of it. --------------------------------------- (Mr.) Taka Kamiya KB4EMF / ex JF2DKG On Friday, April 3, 2020, 3:21:09 PM EDT, Mike Ingle <finndmike62@gmail.com> wrote: Hello fellow nuts, I just received my PRS-10 with boardlet and heat sink, and I have a question regarding my PPS output signal. My output looks strange, (but usable). I have attached a couple screen-shots of my scope/ The first is with 50 ohm termination after 5foot of 5g-58 cable, the second is without termination. --mike [image: pps_term.png] [image: pps_unterm.png] _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.

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PRS-10 PPS output