BT Hawk Tester

Liam1f · 4 Jun 2010

I have recently bought a BT Hawk tester, with an intention of using the TDR function to check for damaged cables.
This machine does far more than I was expecting it to, and did not come with a user manual.
I can figure out quite a lot by just playing about with it, but does anyone know how to use it for real? Particularly the TDR function?
I have contacted Spirent, the manufacturers, who have advised that there is a whole section on the BT intranet about the Hawk; unfortunately, I am not a BT employee.
I actually intend to use the machine on plant machinery, to find damage in wiring looms. (I realise this is off-subject, but I'm hoping the people with the knowledge will be in this forum).
I'm not sure what I can offer in return. I'm a bit of an all-rounder in knowledge and experience (jack/master etc.) but might be able to help others, somewhere!

OwainDIYer · 4 Jun 2010

Although it looks a bit spammy on google at the moment, there is probably someone on news:uk.telecom who could help.

Note · 5 Jun 2010

the peaks or spike in the TDR show breaks and the troughs or downward spikes show looped connection.

the larger the peak the greater the break same aplies for troughs.

but just a note not all peaks are breaks. slight rises ot falls could simply be a connection point

takes a bit of getting used to. best used on a sinlge pair if wires with few connections. as more connections will maket it less accurate

casius66 · 5 Jun 2010

http://www.jmwlimited.co.uk/Tester_301C_Cable_Fault_Locator.html

Is it anything like this one?
PDF instructions may be of use...

disinfo · 5 Jun 2010

Liam1f said:
I actually intend to use the machine on plant machinery, to find damage in wiring looms. (I realise this is off-subject, but I'm hoping the people with the knowledge will be in this forum).

Hi there, not sure how accurate the hawk will be for this purpose.

TDR's usually have a programmable NVP (Nominal velocity of propagation) this essentially relates to how thick the copper conductors are.

Plant machinery, wired in Tri-Rated and 2491X etc is likely to be outside of the range of the hawks setting for NVP.

Liam1f · 5 Jun 2010

Hi All, many thanks for the info.
Note: Peaks and troughs are obviously the bits to remember. (Troughs=low=short?) Thanks!
Casius66: I have gleaned what I could from that. They can't be too disimilar. Thank you.
Disinfo: That was quite an eye-opener! I am hoping that by comparison to good wires, I will gain some insight. I've got a lot to learn! Thank you.
Cheers.

Note · 6 Jun 2010

thats right.

the default setting for cable diameter is 0.5mm

it can be changed using the button on the side of the display.

you can make to display more accurate using the up arrow to the side of the display but you can make it too accurate on the longer lines. this will show up most cable imperfections which would not affect the cable performnce.

just keep an eye for the larger unusual peaks.

you can also change the voltage settings but for best results disconnect from any power supply

Liam1f · 6 Jun 2010

Thanks very much for the advice.

I have figured out how to change the wire settings, but not the volage settings yet. Is there also a way to change units? (Metric to Imperial?)

Also I'm not sure where the test leads should go! There are 5 sockets on the tester, 2 black, 2 red and a green one. There is also a remote unit with the same 5 sockets. There is a Help text which explains how the voltmeter etc. works - 3 at a time - but there's nothing there for the TDR function. Do wires have to be tested in pairs, or can they be done individually?

Note · 6 Jun 2010

you should only need the A and B port and the green is the earth connection, which you wont need if just checking for brakes in line. you will need it if you are checking for battery contacts of earthed connection.
you shouldn't really need the remote unit for what you are testing.

its best to test pairs as thats what its made for

dont think you can change the units either

Liam1f · 6 Jun 2010

Thanks again.

I think I'm ready to try it out for real! Sods Law says I won't need it for ages, now!

otking · 12 Jun 2010

Hi m8,
I use a HAWK regularly, not every single function, but I use TDR a lot. I have noticed that you can adjust the PVF (propagation velocity factor), which is equivelent to the NVF, mentioned before. Its default is 0.67 I think, i.e. signal is expected to propagate at 67% speed of light. PVF is definately affected by conductor type (ali, copper etc...) & insulation, may be affected by cable construction and conductor gauge too though, not sure? Try experimenting with known conductor lengths & type while changing PVF to see what gives good results.

Hope this helps

Liam1f · 12 Jun 2010

Thanks very much for the info. I reckon, with a bit of time and effort, I could make a quick-reference table of the wires I might need to test.
This really is a handy bit of kit!

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