The TB's PPS output has something like 5 ohm output impedance. It is very desirable to terminate the coax cable with 50 ohm at the other end, otherwise you will get endless ringing
The following web page uses the PPS output of the Thunderbolt to illustrate ringing in a non-matched cable: http://www.ko4bb.com/Test_Equipment/CoaxCableMatching.php And this page shows a minimum, energy efficient pulse stretcher: http://www.ko4bb.com/Test_Equipment/Thunderbolt/PulseStretching/ Didier KO4BB > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Scott Mace > Sent: Saturday, August 09, 2008 5:41 PM > To: Discussion of precise time and frequency measurement > Subject: [time-nuts] Thunderbolt PPS output > > Has anyone used the thunderbolt PPS output with a N8UR > FatPPS? I'm seeing a large (+-100-300us) amount of jitter on > the output of the FatPPS. This same setup works fine with > the input from z3801a (using a PECL/TTL converter) or the > Fury (even though the Fury's pulse is wide enough to begin with). > Is there something special about the thunderbolt PPS output? > I noticed it seemed to require 50ohm termination to get a > clean signal when I connected it to a counter (5334a) with a > 3 foot cable. > > I'm using the FatPPS in conjunction with a soekris 4501 with > the tmrin mod. > > Scott > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, > go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
