Strange RG-59 cable!?

[be236]

Hi,

One of my 50ft RG-59 cables wasnt working to hook up LNB to receiver, so with my ohmmeter, I got connectivity on both ends of the center conductor wire.

Then I measured for connectivity on the other sheath and got nothing (essentially infinite resistance)...

So I cut one of the connector ends out, hoping to make a new connector, thinking the outer shealthing was loose, etc...

Turns out... there is NO outer shealth...

What does this mean? Is this a funky/special RG-59 cable? I mean I can use it to hook up between the RF out of my receiver to my TV and it seems to work fine (I can see a picture), but it doesnt work for LNB to receiver because it needs both wire lines to loop to bring the LNB power to ground, etc.. I know about that...

the question is.. what's up with this funky cable that doesnt have the outer shealth? heh...

[crankbooster]

It is more advisable to use a R6 cable for satellite connection

[be236]

Ummm... I already know about that... I'm using RG-6 right now...

My question was about this RG-59 cable, regardless of its use for satellite or et al.

[bobkat]

There is an outer sheath - it probably fell off when they stripped the wire to put on the connector. It may look like a foil braid - its hard to see sometimes but its there, or else there would be no current flow, IF or RF.

kat

[be236]

No. there's not... I've cut the cable about 6 inches down from where it was.

I've put on F-connectors before and I know what the outer sheath looks like... it's like braided-hair-like wires.... there are no hair-wires! What I see is basically an aluminum cover wrapping around the middle white conical plastic part. There is no conductivity of this aluminum wrapping.

As for signal, apparently somehow when no voltage is required on the line, the cable with its center wire is good-enough to transmit data since I know it works from receiver to TV just fine.

Might be a DUD cable / lemon / error cable.

It happens with networking cables as well.
1 poor spun copper cable and the other 5 ? is working fine. Might be a brake or weak joint in between 2 spools on the manufc. machine.

Usually the more expensive the more they tested and made sure it is working.

The manufacturing machine most probably ran out of the missing part and the inspection guy was asleep LOL.

Is it a good name brand or funny cable company stuff LOL.

[be236]

D'oh okay... I guess it was just a bad pre-made cable that got manufactured and that shealth never made it on and the outer rubber skin was slapped/molded over it w/o any QC-ing. heheh... d'oh.

[radiobob]

The foil wrap around the dielectric (the center insulation) is the shield! In theory, the hollow tube part of the F-connector will make contact with the foil and when crimped in place, there'll be a ground return...but, you see how well that theory works.

Also, it is not unheard of for a conductor to show open to DC but present a path for RF (and vice versa). It's magic stuff!

That said, you are making the smart choice to ever-so-neatly cram that junk cable into the trash. I'm going to make up a little ditty for the occasion:

"If the cable has no braid,
Of it please be afraid.
If the cable has nice shield,
Nice signals it will yield!"


Needless to say, "your mileage may vary" and there actually are high-quality cables that make use of foil shield--but, they usually have some sort of braid.

Bob

[bobkat]

Originally Posted by be236

No. there's not... I've cut the cable about 6 inches down from where it was.

I've put on F-connectors before and I know what the outer sheath looks like... it's like braided-hair-like wires.... there are no hair-wires! What I see is basically an aluminum cover wrapping around the middle white conical plastic part. There is no conductivity of this aluminum wrapping.

As for signal, apparently somehow when no voltage is required on the line, the cable with its center wire is good-enough to transmit data since I know it works from receiver to TV just fine.

That aluminum cover wrapping is the sheath. That's what I said before that sometimes it looks like a foil wrap. Its not always a braided hair-like wire. So like WarraWarra said, perhaps there is a break somewhere inside the cable. There is NO WAY any cable would transmit RF (or anything else for that matter) with only one conductor. You should take a course in basic electrical theory before you get so cock sure of what you say.

kat

[rainman]

Originally Posted by radiobob

The foil wrap around the dielectric (the center insulation) is the shield! In theory, the hollow tube part of the F-connector will make contact with the foil and when crimped in place, there'll be a ground return...but, you see how well that theory works.

Also, it is not unheard of for a conductor to show open to DC but present a path for RF (and vice versa). It's magic stuff!

That said, you are making the smart choice to ever-so-neatly cram that junk cable into the trash. I'm going to make up a little ditty for the occasion:

"If the cable has no braid,
Of it please be afraid.
If the cable has nice shield,
Nice signals it will yield!"


Needless to say, "your mileage may vary" and there actually are high-quality cables that make use of foil shield--but, they usually have some sort of braid.

Bob

love the diddly Bob maybe Sadoun can give you a job singing commercial jingles. LOL

[wejones]

Originally Posted by bobkat

That aluminum cover wrapping is the sheath. That's what I said before that sometimes it looks like a foil wrap. Its not always a braided hair-like wire. So like WarraWarra said, perhaps there is a break somewhere inside the cable. There is NO WAY any cable would transmit RF (or anything else for that matter) with only one conductor. You should take a course in basic electrical theory before you get so cock sure of what you say.

kat

I agree that the aluminum cover is the sheath, however I don't agree re the NO WAY thing about a single conductor transmitting RF. I've used single conductor feed lines a lot, in fact I've seen times when I didn't have the proper antenna for a particular band, that if I connected a coax by just the center conductor, unscrewing the outside ground, that it even worked better.
DC is less forgiving though, but often it can find alternative ways between two devices, like through house power grounds, etc.

[bobkat]

Originally Posted by wejones

I agree that the aluminum cover is the sheath, however I don't agree re the NO WAY thing about a single conductor transmitting RF. I've used single conductor feed lines a lot, in fact I've seen times when I didn't have the proper antenna for a particular band, that if I connected a coax by just the center conductor, unscrewing the outside ground, that it even worked better.
DC is less forgiving though, but often it can find alternative ways between two devices, like through house power grounds, etc.

Yes Bill, but you are talking RF radio waves - I too have used single pieces of coax for antennae and like you have noticed sometimes they work better by not connecting the shield. Hell, my body seems the best antenna at times...

But using a coax cable to run from RF OUT on a VCR or whatever to ANT IN on a TV set would not show a clear picture without the shield connected.

kat

[be236]

Umm.. Kat.. yes, I have already taken electronics theory class for your info, so I know how electricity conducts .. so yes, I am being "cocky."

As I said, I measured that shealth and there's no conductivity (well, unless you call high resistance somewhat conducitivity).. and as I said before, I can get a picture using RF out.. maybe it's not clean but it is still a picture...

And as Bill said, DC is less forgiving, and hence that's why it gets no power to LNB and so it dont work in that configuration.

Also, I've cut cables before and I "usually" see the foil shield shealth AND the braided wires which is the ones that gives me conducitivity, and hence that's why I was asking why it was strange to NOT see this braided wires in my particular cable.

[bobkat]

I know the cable you are talking about - its that really cheap stuff you buy for like $1.99 for 25 feet with F-connectors on it. Its total junk - it has only the foil and no braided shield at all. Like radiobob says ... "Trash it".

kat

[be236]

Yeah, that sounds about right... I have no idea where I got this cable from.. it's just laying around the house among other cables I've collected over the years (heh)... and it seems like junk after all this discussion.. though it can be used as a "poor man's" cable to connect a receiver to TV... it just cant be used to send DC volts across the line, which it was probably not designed for ... oh well ...

I guess we can pretty much close this thread now.... on to better topics.. heh..