What threshold are you using? If you leave it set to preset/0 volts, you may find that crosstalk between outputs on the TADD-2 cause false triggering. I usually use the divide-by-10 setting with the threshold set to about 0.25V.
It also helps to remove the jumpers from any outputs on the TADD-2 you aren't using. -- john, KE5FX > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on > Behalf Of Dave hartzell > Sent: Sunday, February 28, 2010 7:28 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Achieving maximum performance when driving > 5370A/Binputs > > > Today I have been trying to drive a 5370B directly from a TADD-2, with > little luck (other HP freq counters seem to work OK). I was about to ask > about it on this list, but noticed this thread. > > I guess this could explain why I am getting erroneous, random readings? > > Dave > > > > On Sat, Feb 27, 2010 at 4:01 PM, Bruce Griffiths > <bruce.griffi...@xtra.co.nz > > wrote: > > > The attached excerpts from the 5370A and 5370B manuals indicate that for > > best performance, that the common practice of driving the > 5370A/B 1x inputs > > directly from a 5V CMOS logic signal is a bad idea. > > > > For the 5370A attenuating the 5V CMOS signal to a 1V swing with the > > threshold set to 0.5V is close to optimum. > > An input signal with limits of 0V and +1.4V with a trigger threshold of > > 0.7V is the maximum usable (for high performance). > > An input signal with limits of 0V and +0.3V with a trigger threshold of > > 0.15V is the minimum usable (for high performance). > > > > For the 5370A attenuating the 5V CMOS signal to a 2V swing with the > > threshold set to 1V is close to optimum. > > An input signal with limits of 0V and +3.5V with a trigger threshold of > > 0.7V is the maximum usable (for high performance). > > An input signal with limits of 0V and +0.3V with a trigger threshold of > > 0.15V is the minimum usable (for high performance). > > > > Bruce > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.