Home |
Search |
Today's Posts |
#1
|
|||
|
|||
rf pulse width measurement
I am trying to measure the width of an S band pulse. The circirt
consist of a transmitter wave guide and the dummy load with two identical directional couplers mounted abot 4 ft apart. The pulse width measured at the DC closest to the transmitter is measured at 1.05uS Measure ment is made through the 20 db port on the coupler a 20 db pad, doide detector good from .1MHz to 12Ghz. 100Mhz scope calibrated in the last week.. Same results with another scope. the other point of measurement uses the same type DC, connection to the 20db port then a 3db splitter then 20 db pad then the detector and pulsewidth measure .96uS. VSWR is 1.17 Other port on the 3db splitter has a 30 db pad What could account for the difference in pulsewidths at the two ports. Jimmie |
#2
|
|||
|
|||
rf pulse width measurement
"JIMMIE" wrote in message oups.com... I am trying to measure the width of an S band pulse. The circirt consist of a transmitter wave guide and the dummy load with two identical directional couplers mounted abot 4 ft apart. The pulse width measured at the DC closest to the transmitter is measured at 1.05uS Measure ment is made through the 20 db port on the coupler a 20 db pad, doide detector good from .1MHz to 12Ghz. 100Mhz scope calibrated in the last week.. Same results with another scope. the other point of measurement uses the same type DC, connection to the 20db port then a 3db splitter then 20 db pad then the detector and pulsewidth measure .96uS. VSWR is 1.17 Other port on the 3db splitter has a 30 db pad What could account for the difference in pulsewidths at the two ports. Jimmie so on the 2nd port there is an extra 3db splitter. have you tried it without the splitter so the same load is on both ports? Do the pulses both look the same shape? more rolloff on the one on the second port maybe? perhaps a lower sample power is changing the diode response, that is the detector may not be completely linear. when you measure the 2nd one do you remove the detector from the first port and move it? or do you have a 2nd detector that is always hooked up on the 2nd port? If you move the detector maybe it changes the load at that point enough to affect the pulse shape at the 2nd port? |
#3
|
|||
|
|||
rf pulse width measurement
On Nov 2, 5:30 pm, "Dave" wrote:
"JIMMIE" wrote in message oups.com... I am trying to measure the width of an S band pulse. The circirt consist of a transmitter wave guide and the dummy load with two identical directional couplers mounted abot 4 ft apart. The pulse width measured at the DC closest to the transmitter is measured at 1.05uS Measure ment is made through the 20 db port on the coupler a 20 db pad, doide detector good from .1MHz to 12Ghz. 100Mhz scope calibrated in the last week.. Same results with another scope. the other point of measurement uses the same type DC, connection to the 20db port then a 3db splitter then 20 db pad then the detector and pulsewidth measure .96uS. VSWR is 1.17 Other port on the 3db splitter has a 30 db pad What could account for the difference in pulsewidths at the two ports. Jimmie so on the 2nd port there is an extra 3db splitter. have you tried it without the splitter so the same load is on both ports? Cant do that Do the pulses both look the same shape? Yes more rolloff on the one on the second port maybe? No perhaps a lower sample power is changing the diode response, that is the detector may not be completely linear. Thats what I was thinking but i didnt think 3db would make that much difference when you measure the 2nd one do you remove the detector from the first port and move it? yes, same detector used on both ports. or do you have a 2nd detector that is always hooked up on the 2nd port? I doubt it 40db of isolation betwen the detector and the waveguide If you move the detector maybe it changes the load at that point enough to affect the pulse shape at the 2nd port?- Hide quoted text - - Show quoted text - I thought about that thw extra 3db may make some difference but I cant take it off without taking the equipment down. I have a variable 100db attenuator and I think I may do some experiments this weekend and see what kind of effect changes in power level will have on the measured pulse width. Jimmie |
#4
|
|||
|
|||
rf pulse width measurement
On Nov 2, 9:15 pm, JIMMIE wrote:
On Nov 2, 5:30 pm, "Dave" wrote: "JIMMIE" wrote in message roups.com... I am trying to measure the width of an S band pulse. The circirt consist of a transmitter wave guide and the dummy load with two identical directional couplers mounted abot 4 ft apart. The pulse width measured at the DC closest to the transmitter is measured at 1.05uS Measure ment is made through the 20 db port on the coupler a 20 db pad, doide detector good from .1MHz to 12Ghz. 100Mhz scope calibrated in the last week.. Same results with another scope. the other point of measurement uses the same type DC, connection to the 20db port then a 3db splitter then 20 db pad then the detector and pulsewidth measure .96uS. VSWR is 1.17 Other port on the 3db splitter has a 30 db pad What could account for the difference in pulsewidths at the two ports. Jimmie so on the 2nd port there is an extra 3db splitter. have you tried it without the splitter so the same load is on both ports? Cant do that Do the pulses both look the same shape? Yes more rolloff on the one on the second port maybe? No perhaps a lower sample power is changing the diode response, that is the detector may not be completely linear. Thats what I was thinking but i didnt think 3db would make that much difference when you measure the 2nd one do you remove the detector from the first port and move it? yes, same detector used on both ports. or do you have a 2nd detector that is always hooked up on the 2nd port? I doubt it 40db of isolation betwen the detector and the waveguide If you move the detector maybe it changes the load at that point enough to affect the pulse shape at the 2nd port?- Hide quoted text - - Show quoted text - I thought about that thw extra 3db may make some difference but I cant take it off without taking the equipment down. I have a variable 100db attenuator and I think I may do some experiments this weekend and see what kind of effect changes in power level will have on the measured pulse width. Jimmie- Hide quoted text - - Show quoted text - Ok, it seems like depends on how much power you are putting into the detector to start with whether or not another 3db matters. Nice to know it was set up on the hairy edge like this. Jimmie |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
50r pcb stripline width?? | Homebrew | |||
pulse radio help | Antenna | |||
[WTB] JRC CFL-243W BAND WIDTH CONTROL UNIT | Shortwave | |||
pulse transformers | Homebrew | |||
50r pcb stripline width?? | Homebrew |