Tektronix 284 pulse generator, problems with the fast pulse - Page 1
Forum section: electronics / rf-microwave

author: Physikfan
author_rank: Regular Contributor
timestamp: October 04, 2017, 09:22:01 am
content: Hello Tektronix friendsAfter turning on a Tektronix pulse generator 284:and after a slight adjustment of tunneldiode bias (TD bias), a screw drive adjustment on the front panel,the fast pulse output is about 200 mV amplitude and about 65ps rise time,Oscilloscope is a 11402 with a Tek 11A72 with 1 GHz bandwidth:Abscissa 5us / div, ordinate 50mV / divAbscissa 1ns / div, ordinate 50mV / divAfter some time, a few minutes, the pulse is gone:Abscissa 2us / div, ordinate 50mV / divAnd this fast pulse does not come back!Who knows any advice?VGPhysikfan

author: Physikfan
author_rank: Regular Contributor
timestamp: October 06, 2017, 03:32:12 pm
content: Hello Tektronix friendsI have found some interesting facts in the instruction manual of Tek 284:This means that mechanical stress at the output socket (GR878) may influence the electrical characteristicsof the tunnel diode.And with the heating of the device after switching on one must change the tunnel diode bias.Trigger signal and fast pulse, about 200 mV amplitude and about 65ps Rise time:RegardsPhysikfan

author: doktor pyta
author_rank: Frequent Contributor
timestamp: October 07, 2017, 08:26:16 pm
content: It seems that front panel TD bias adjustment range is not sufficient. Inside there is R133 coarse TD bias potentiometer. Try to use it with front panel TD bias potentiometer centered. TD bias changes with temperature so it should be adjusted after warm-up time.

author: Physikfan
author_rank: Regular Contributor
timestamp: October 09, 2017, 10:29:48 am
content: Hi Doktor PytaI will do it within my next free hours.In the mean time I have found an always working Tektronix pulse generator 284:The fast pulse, shown with a Tektronix 7904, plugin 7A29 for the fast pulse, plugin 7A19 for the trigger signal:Above the entire fast pulse, below the trigger pulse, x-axis 200 ns / div, y-axis 100mV / div:Above the fast pulse, below the trigger pulse, x axis 10 ns / div, y axis 100mV / div, 5 ns lead time (lead time)Above the fast pulse, below the trigger pulse, x-axis 10 ns / div, y-axis 100mV / div, 75 ns lead timeAbove the fast pulse, below the trigger pulse, x axis 5 ns / div, y axis 100mV / div, 5 ns lead timeAbove the fast pulse, below the trigger pulse, x axis 1 ns / div, y axis 100mV / div, 5 ns lead timeDisplayed rise time of the pulse is about 500 ps (Tek 7904).RegardsPhysikfan

author: Physikfan
author_rank: Regular Contributor
timestamp: October 13, 2017, 09:32:25 am
content: Now, images of the fast pulses of the working Tektronix pulse generator 284 with an 11403:11A72 for fast pulse, white, below the trigger pulse, red, x-axis 10 ?s / div, y-axis 100 mV / div, 5 ns lead time:Above the whole fast pulse, white, below the trigger pulse, red, x-axis 200 ns / div, y-axis 50mV / div, 5 ns lead time:Above the fast pulse, below the trigger pulse, x axis 20 ns / div, y axis 50mV / div, 5 ns lead timeAbove the fast pulse, below the trigger pulse, x axis 10 ns / div, y axis 50mV / div, 75 ns lead timeAbove the fast pulse, below the trigger pulse, x-axis 1 ns / div, y-axis 50mV / div, 5 ns lead timeDisplayed rise time of the pulse with the 11403 less than 300 ps.RegardsPhysikfan

author: Physikfan
author_rank: Regular Contributor
timestamp: October 14, 2017, 10:04:58 pm
content: An image of the fast pulse of a working Tektronix pulse generator 284 with a Tektronix TDS820 6GHz, 44 ps Rise time:x axis 50 ps / div, y axis 50 mV / div, 5 ns lead time:An image of the fast pulse of a functioning Tektronix pulse generator 284 with a Tek TDS820 6GHz, 44 ps Rise time:x axis 20 ps / div, y-axis 50mV / div, 5ns lead time:The displayed rise time of the pulse with the TDS 820 is less than 100 ps.