SWEEP OF RF CABLE

[Alwayslearningelec]

DOes anyone know what a "sweep" of RF cabl;e would entail/mean? Thanks.

 

[jumper]

Bending radius. Sweep elbows/ells are more gradual in the turn.

 

[grich]

Or testing the cable with a signal generator and analyzer to make sure the cable is within spec

 

[Alwayslearningelec]

Or testing the cable with a signal generator and analyzer to make sure the cable is within spec

Thanks GRICH. Can you elaborate a little more about what the test does. THanks A LOT!!

 

[hbiss]

It tests the cable (usually coax) to see if it is within manufacturers specs. Coax can be damaged by improper handling, dents, tight bends, water ingress, high heat, age- any number of things. These things will often show up as increased attenuation at some or all frequencies depending on the defect. A sweep test applies a fixed level variable frequency signal to one end of the cable that is measured and recorded at the other. The variable frequency begins at the lowest frequency you want to measure and ramps up to the highest frequency. An X/Y axis graph is generated by the sweep receiver at the other end- frequency vs attenuation. You can then compare that to the graph provided by the manufacturer or see right off what some problems are by their "signature".

Another useful test is with a TDR that will actually show where along the cable any problem is.


-Hal

 

[jumper]

Sorry Horsegoer, I saw sweep and thought you were talking about installing IT cables in conduit.:slaphead:

IT types are always specing oversized conduit and sweep elbows.

 

[grich]

It tests the cable (usually coax) to see if it is within manufacturers specs. Coax can be damaged by improper handling, dents, tight bends, water ingress, high heat, age- any number of things. These things will often show up as increased attenuation at some or all frequencies depending on the defect. A sweep test applies a fixed level variable frequency signal to one end of the cable that is measured and recorded at the other. The variable frequency begins at the lowest frequency you want to measure and ramps up to the highest frequency. An X/Y axis graph is generated by the sweep receiver at the other end- frequency vs attenuation. You can then compare that to the graph provided by the manufacturer or see right off what some problems are by their "signature".

Another useful test is with a TDR that will actually show where along the cable any problem is.


-Hal

Thanks, Hal for answering while I was out inspecting an AM transmitter site...you 'splained it better than I could, anyway.

Our Fluke DTX1800 can sweep coax up to 900MHz as part of its testing, although we didn't buy the coax interface kit...we just use it to certify our CAT6 runs.

 

[grich]

...IT types are always specing oversized conduit and sweep elbows.

You'd be surprised how fast those conduits fill up sometimes. Gotta have the sweeps to respect minimum bend radius specs, and to make it easier on this old man pulling cable.

 

[jumper]

You'd be surprised how fast those conduits fill up sometimes. Gotta have the sweeps to respect minimum bend radius specs, and to make it easier on this old man pulling cable.

I got no problem with that, except many times I have ran a 2" conduit and sweeps and it turns out to be 2-3 Cat 5 cables. I get paid by the hour, so: not my problem.

 

[ActionDave]

What we need is more IT guy engineering and less value engineering. That would be a way to fuel the economy.

 

[stevenj76]

That's the freq sweep and TDR test. Your test equipment will have to be cal'd and capable of a print-out.

 

[hbiss]

What we need is more IT guy engineering and less value engineering. That would be a way to fuel the economy.

Right. 4" conduit for everything, 6 runs of CAT7 to every location and everything gets certified twice.:thumbsup:

-Hal

 

[Hv&Lv]

Right. 4" conduit for everything, 6 runs of CAT7 to every location and everything gets certified twice.:thumbsup:

-Hal

It amazes and confuses me as to why the phone companies want a 4" conduit to install a 6 pair phone line. Maybe when they replace it the fiber will need 4".:lol:

 

[hbiss]

It amazes and confuses me as to why the phone companies want a 4" conduit to install a 6 pair phone line. Maybe when they replace it the fiber will need 4".:lol:

It dates back to the old Bell System days when they ran much larger cables, wanted the capacity to add more later and materials were cheaper. The specs were never changed and they figure better too big than too small.


-Hal

 

[iwire]

I got no problem with that, except many times I have ran a 2" conduit and sweeps and it turns out to be 2-3 Cat 5 cables. I get paid by the hour, so: not my problem.

Or how many times we have run a pair of 4" to have the telco pull one 25 pair cable in ......