Client has a Sunbrite TV outdoors connected to a Comcast box indoors, guessing 100' away, connected with cat5e. Snap 520 series extenders have worked for some time, but now the "LINK" LED is not lit.

Seeing EZ connectors, I replaced them with standard RJ45s, no change.

Grabbed a newer Snap extender, no change.

Grabbed a Zektor extender, still no link LED.

Simple cat5 tests show good, passed, no opens or conductors crossed.

Next I grabbed a Byte Brothers Real World Certifier that I got from Paul here (thanks, man!) and put it in action. I am not familiar with what I should see or should not, but here's what I found.

Again, continuity tests were good. Showed 215' of cable! But it has a data test of sorts that seems to indicate what speed the cable will pass. A graph showing cable speeds from cat3, 5, 5e, 6 indicates it may be passing slightly over 10mb/s, which it indicated is closer to cat3 speed. I don't know for sure if this is the problem or an indicator of something else to look for. There were also readings for skew, etc, but I am not sure how to interpret that.

Anyone who uses that tester or who has insight, I will really appreciate your input and advice.

Which tester is it?

If the speed test is anywhere near accurate, then that certainly is a problem. HDBaseT speeds are near 10g speeds.

Is the cable buried? Water infiltration over the years, would be a likely suspect. Especially if it wasn't burial rated cable (that includes in a conduit).

Real World Certifier

So has anybody ever used data from a ethernet cable tester to diagnose an HDbaseT problem before?

The wire mapped out all OK? No shorts? I would think if degraded by water or even a lightning strike wouldn't there be a short in the cable?

You mention its approx a 100' run but the tester is showing 215'. This is making me think short if it truly is closer to a 100' run.

Are you sure you are reading that speed test right. Why would 10G be cat3 speed? Unless its 10mbps and not 10G.

You are right, I just looked over the test again and it is slightly over 10mb/s which is likely too low a data rate for an extender.

This is what I am supposing anyway. It appears that most folks just use it for checking runs after a prewire, and maybe it has not gotten a lot of use as a troubleshooting tool in this type of situation (HDbaseT).

Thank you for your input.

No. Degraded by water or lighting strike will NOT show up as a short a lot of times.
You are dealing with a signal. A signal that has bandwidth. Testing for a short or open circuit is only good for a DC (or close to DC) circuits. Catastrophic failure if you will.
If you take 100 feet of lamp cord and run 4 pair of it, it will test fine for shorts or opens. However you are not going to run a 10G network over it.

Which runs us into HDBaseT speeds. You are dealing with a 10G network connection there. It is truly amazing that the manufactures have got these devices to work over cat5e, the distances that they do. But we all know how finicky the connections are, because we are pushing the bandwidth so hard.
A meter to test 10G speeds properly, cost thousands of dollars. And with 4K HDR @ 18Gbit/s now, I don't even know what testers can fully certify that.

But with a simple meter like Tom's, testing out to Cat6 standards, can still tell us a lot. In this case, the meter couldn't do maximum bandwidth that it can do over this cable. Which means there is a problem with the cable, as it will need to max out his meter as a minimum in order for his HDBaseT extender to function properly. "If accurate", his meter has severed him well.
If the meter had shown it could pass its maximum bandwidth on this cable, then there could have still been an issue. As the cable might not be able to pass that highest bandwidth only, something his meter wouldn't be able to test for. Requiring a much more expensive meter to test with.

But the simple solution most of us do - run a new cable temporarily across the ground and see if it works. If it works on the temporary cable but not the one in the ground, Bingo! No expensive tester needed.

Beat me to it. What he said ^

Yes. But there are 2 things to that.
1) It is not always possible to run a temporary cable, as obstructions such as walls and things might be in the way.
2) The time taken to spool out a temporary cable, terminate it and test again. Plus the cost of your cable and ends.

A nice meter would save you a lot of time & materials. But of course at the expense of the cost of the meter.

Another advantage of using a meter — certify the initial installation. Keep records of the test results. Ideally, the cables can be certified before the walls close and again at final fitout. Now is the time to deal with site damage and the numbers will help settle disputes. Later, if problems develop, you can easily measure a change.

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I’m trying, not very successfully I’m afraid, to come up with a quick explanation of why one must be gentle with category cables, why a simple continuity check is not the whole story about cable health, and why a high tech meter is the better tool.

Consider this: If one was attempting to distribute off the air analog TV, cable TV, or satellite signals, one would pick a 50, 75, or 300 Ohm scheme. Everyone knows (or should know) that there is a family of fittings with each of these schemes and that there are consequences for mixing fittings and cables. When there is an impedance mismatch, some energy is absorbed at the transition and a reflection is generated. In long runs (of analog TV) one can actually perceive “ghost” images. In shorter runs there is some smearing of the image that is hard to characterize. The physical aspects of the cable and fittings are extremely important. A crush point or too sharp bend changes the impedance, causing some signal loss and reflections at the transition.

For the sake of discussion let’s send a single pulse through our transmission line (cable). We have a signal starting at point A, meeting impedance issues at B and C, terminating at D. When the pulse hits B most of the signal will continue to C, but a portion will reflect back to A. If things are not quite right at A, a portion of BA will be reflected and head back to B. Since everything travels at the same speed per foot, the reflections arrive little later and combine with the actual signal. The same process is working between B and C, C and D. In a sense we launch a single pulse from A toward D, but a smeared blizzard arrives at D.

This is over simplistic, but I hope that you get a sense of what is happening.

In our Gigabit network, too tight bends, crushes, and splices result in impedance changes and a smearing of the nice digital signals we are pushing. A little smearing is tolerated, but if the smear is still cooking at the expected time of the next pulse arrival, we are in trouble.

The sophisticated testers allow us to put some numbers on the maximum successful transmission rate. Lower data rates are less bothered by cable issues.

Water in a cable that was designed to be filled with air, will cause a dramatic impedance discontinuity. But, the wire map is fine.

By the way the TDR testers measure the reflection. Assuming that the cable is uniform to the problem area, it is easy enough to calculate the distance to the fault. It is very handy to know where a shark bit the undersea cable.

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Edit: By the way when we are laying out transmitters, we fuss with the SWR (Standing Wave Ratio). This is another facet of the same coin. For transmitting antennas we would like maximum energy to be launched into the air, not reflected back to be absorbed by the cable and transmitter. Multi-megawatt pulses meeting a soggy, wet section of cable can result in some interesting surprises (as the water absorbs a little of that energy). In receiver systems an unfortunate SWR will result in a bad signal to noise ratio.

Wikipedia TDR article.

I agree on the temp cable in many situations but probably not necessary now. wouldn't what has already been done, by Tom, pre-tester already prove that its a cable issue?

Tom,
Is it run in a conduit between indoors, where a new one could easily be pulled, or was this just trenched and buried in the ground? Is that Cat5e DB Rated?

It's a takeover so I am unsure. Will have to go back of course and check on the DB aspect. So far, I see the cable poke through the cabinet to go under the house, and it shows up at the outdoor location, coming up through a 1/2" conduit.

I am not looking forward to dealing with it. The straight path from house to TV is on the order of 100', while the cable checks out at 215' according to test results. The straight path would be under a brick patio/walkway, thus I assume the cable runs under the house waaaay down to the far end, where a conduit could have been laid to run the rest of the way.

Maybe the homeowner can fill in some blanks for me.

The "real world" aspect of the rest results interest me. When a thread pops up "What tester should I get", there are many opinions from people who own the things, but apparently there is not a great deal of understanding beyond "pass/fail" type results. The cable passes, great, but what about when it fails? If a crossed pair, you just change the end and done. I am getting the impression that few have seen much more than that, indicating data testing may not do most of us any good. A basic VDV tester may be all that we need.

I have had wire map pass. No shorts etc and the damn thing still won’t link up. Swap cables and all good.

This was to a sunbrite using snap 540 balun.

I was using structured cable products shielded direct burial cat 6. At first I noticed wiggling wire at balun would occasionally make link light. So I test cable. No issues. Wiggle cable every which way while testing. Passes. Swap to a second non direct burial cable. Worked fine. Said wtf. Ran a new length of direct burial. Same bs. Swapped baluns to another 540. Issue worse. Cable certifies.

Ultimately I said screw it and am running off the non direct burial wire. When I was talking to snap tech he said they were seeing issues on the 540.


Speed tests are indeed valuable. Very valuable. A cable can pass a wire map all day long but still not pass the speeds. A good meter is $1500 or so that can do this well. A cable “certifier” and “qualifier” are two diff things. Only one is actually a true legit speed rating you can sign off on during a prewire.

[Link: m.flukenetworks.com]

IMHO a VDV is very limited. In no way whatsoever is it all we need. In this business we all should be budgeting sooner rather then later for a tester that can certify a cable. It absolutely is a very valuable tool in network cable troubleshooting (even in HDMI balun usage).

Length could just be off if tdr isn’t calibrated right on that meter. Check with a known length of cat cable.