swingbyte wrote: > Bruce Griffiths wrote: >> swingbyte wrote: >> >>> Bruce Griffiths wrote: >>> >>>> swingbyte wrote: >>>> >>>> >>>>> HI all , >>>>> I had a 5370 A shipped to me that suffered enough of a drop/roll to >>>>> break a handle and bend the chassis such that the bottom panel had to >>>>> be modified to get it back on. When I connected the timebase output >>>>> to the start input the frequency display is 10.0000000xx with the >>>>> last >>>>> two numbers moving about quite a lot. Could this indicate damage to >>>>> the oscillator due to the drop? I haven't tuned up the inputs yet so >>>>> this may be an artefact of that. >>>>> Thanks >>>>> >>>>> Tim >>>>> >>>> Tim >>>> >>>> What gate time was used to measure the frequency? >>>> >>>> Bruce >>>> >>>> >>>> _______________________________________________ >>>> 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. >>>> >>>> >>> Hi Bruce, >>> With a 1s gate time it ranges from 9.999 999 996 to 10.000 000 012 >>> MHz The 5335 with a 1s gate time gives 10.00000101 with the last >>> digit flickering 0. Of course what's really bad is I have two clocks >>> to check now. The std deviation as measured by the 5370 of the 5370 >>> clock is ~1.8 kHz while the std dev of the 5335 clock is 7.8 kHz - >>> both have 10811 OCXOs.. The 5335 measures the 5370 clock std dev as >>> 4.35mHz. I think I'll have to check these against the Rb as I don't >>> have a GPSDO yet. >>> Thanks >>> >>> Tim >>> >>> >>> >> Tim >> >> What was the gate time used for the STD deviation measurements? >> >> Bruce >> >> > I used a 1s gate time on the 5335 and 100ksamples to get a std > deviation of 4.35mHz (thats milli Hertz) so I hope that means they > are both (5335 & 5370) fairly stable. With a 1s gate time on the > 5370 the reading is 10.000 000 000 3 to 10.000 000 001 2 MHz. which > I read as 1 part in 10E10. On the issue of 5370 gate time for the > std dev is 1 period and 100 samples. The 5335 measures the clock of > the 5370 as 10.000 001 06 so maybe one of the 10811s is 1Hz high? The > problem of two clocks. > For the performance tests I get the following results: > (13) period 100.00 +-1ns =>101.17ns > (14) => 101.1843ns > (15) jitter test should be <100ps => 38ps > Trigger levels range from -1.34V to +0.61V > > My unit is a 2036A ser # so the first to have the 10811 as standard- > still only 29 years old! > What is the "ic rot" John was talking about and what solutions are > out there? > > Thanks for your help > Tim > The IC rot sounds like a corrosion or contamination problem that (gradually?) changes the IC characteristics. The only cure is to replace the affected ICs and/or input board(s) with versions that don't suffer from the effect.
My 5370A is a similar vintage (first owner Motorola - they last calibrated it in 2002) without an internal 10811A. Jitter is about 15ps when measuring the period of its own 10MHz output. One of the HP counters (5345A) of a similar vintage used virtually identical input amplifiers. Bruce _______________________________________________ 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.
