1st try TDR

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ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Bought a Time Domain Reflectometer a few months ago with the intent of it helping to find the distance to open conductors that are not grounded or to a fault.

This morning I helped another contractor with a fault locate to lighting above an ATM. I took the TDR along just for experience. 10/2G UF cable was open. TDR said end of cable was at 21.7 feet which put it inside the ATM. DIEBOLD had cut the UF cable to the lights because they thought it was messing up the ATM. Shared Neutral.
 
So did you find your problem?

Often the "foot" reading can be a little off - but easier than deciphering a wave form IMO (Having used both) But once you have a feel for it - it can be a marvelous tool.
 
e57 said:
Was talking about TDR's in another thread last night post >18
http://forums.mikeholt.com/showthread.php?t=96554

Anyway what type, make and model do you have? (Assuming numeric since you mentioned 21.7') How much did it cost, and do you like it?
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Don't know how I missed that thread.

Megger CFL10F. Ebay for $450 give or take. Older, but still had the plastic protective cover over the screen. Just been testing it in the shop and storing various VOP on the laptop until yesterday, so I don't know much about it yet.

Thanks for the hints in your PM, opened my eyes a bit wider.
 
I think I know what I'm going to be playing with next. I've had an old Sencore TDR for a long time, but it never even crossed my mind to use it for this purpose. New stuff to explore...everyone needs a hobby. :grin:
 
ptonsparky said:
Don't know how I missed that thread.

Megger CFL10F. Ebay for $450 give or take. Older, but still had the plastic protective cover over the screen. Just been testing it in the shop and storing various VOP on the laptop until yesterday, so I don't know much about it yet.

Thanks for the hints in your PM, opened my eyes a bit wider.
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The shop I used to work for had the model before the one you have - BEFORE THEY DROPPED DRAMATICALLY IN PRICE! (~2001 or 2) - And it is an excelently made and very usefull tool. And you got it for roughly 1/3 of the new cost at present - great deal!

I will offer these extra hints on its care:
  • Leave it in the shop when not being used - it can be vibration damaged bouncing around in a truck. :roll:
  • Take care not to loose or damage the leads - they are difficult to replace as they are not stock items. Using different or making new ones can effect readings.
  • Remove the batteries and get a case to store it and its stuff when not in use.
Marc - what have you been using your TDR unit for if not for troubleshooting? Just measuring cables at home? :wink: Is it a numeric or graphic?
 
For the benifit of others I suggested in my PM's to ptonsparky to test two #12's laying flat on the floor then twist and bend - short and open them. The waveforms will change and it is good to know how to interpet them.

For some more information take a peek here:
http://www.tscm.com/riprcop.html
As well as all of the links at the bottom of that page....

Other tips:
  • Always test from both ends... if available. Makes pin-pointing things much more acurate.
  • And map and measure the path - use a toner, good one if necessary. Some of the ones on TDR units can leave a little to be desired for that funtion IMO.
  • If other conductors are availble and still good in the cable or conduit - test them too as a comparision for the conductors you suspect at fault. They can give much better VOP settings if you know the length, rather than using VOP settings from a cable in a different condition or environment.
 
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Wow I never thought you could use one on building wire tommorrow I will make up an rj45 to alligator clip whip and test it on a full coil of rx.
 
quogueelectric said:
Wow I never thought you could use one on building wire tommorrow I will make up an rj45 to alligator clip whip and test it on a full coil of rx.
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Not sure which model you have - but be carefull - It sounds as if yours may be Telco/data specific. And the leads are usually calibrated to deal with the "Dark" near-end of the cable. So using a different test lead will give you some odd results. But if you can manipluate the VOP settings to get a more acurate resulution - you can test any two conductors in parralel proximity to eachother. In conduit, any cable of any size etc.
 
FYI - I get excited about tools... And I have not been as excited about a tool as much as I was, and have been since I got turned on to these around 2001/2. :grin: :grin: Other tools are now the equivelent to "gateway drugs" in comparision.

Like any other addiction - use in moderation.... :grin:
 
e57 said:
Marc - what have you been using your TDR unit for if not for troubleshooting? Just measuring cables at home? :wink: Is it a numeric or graphic?
Click to expand...
Got it in with a lot of things from a bankruptcy sale. Haven't used it at all, except to see that it powers up. I think the one I have is geared toward cable TV, but I'll play with it anyhow.
 
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