Increasing Cable TV signal strength

We were required to deliver 0 dBmv at the end of 100 feet of RG-59 or RG-6 for two sets per the franchise. The system was designed at +10 dBmv at the tap to allow for three or four TVs at the 100 foot range. That was on a 36 channel system with RCA modulators & HST. It was done for two reasons. To have a little extra signal available when the system was built, and for conversion for a 300 MHz plant to a 450 MHz plant without respacing the trunk amplifiers.

I build a headend & interface to tie two incompatible community loops together. Ours was a sub split loop, and the other CATV company used mid split. We used 2 & 12 for pilots, so we fed them Channel 2 into their return, and down converted their feed to T-9 for our return. That headend had two RCA HSP and a combiner. The interface was another HSP in a large stainless steel NEMA box mounted to a power pole at the boundary of the two systems. A pair of two way splitters were used to route the signals between the systems, as well as into and out of the HSP. The other company wanted us to install a modulator and a demodulator at the boundary to give us audio & video, and another pair from our side so the interface would be baseband. Their design was over $15,000 in hardware alone. My design was under $3000 for all the hardware & labor to install. I had system designers from both sides telling me it wouldn't work, but it did the job with no problems. :)

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You can't have a sense of humor, if you have no sense.

Very nice. We were much more constrained on the install I mentioned up the thread a ways. The fiber was fed at E1 speed, which probably didn't work it very hard.

We had an issue at one point.

This was a distributed proc/data system, one of the first. Each cabinet was a standalone PBX. And you could make 126 of them look like one. And each could survive on its own.

First fiber campus we'd done. Staggered cut to the new infrastructure. Fun stuff.

At one point we had to do the cutover to the other large pice of the system. Each end connected the fiber. 0 signal.

TDR from A end showed 700 meters from A end, 800 meters from end B. Length from A to B is 1500 meters.

The work that occurred because of that was not fun. Had to go get the guy doing fusion splicing.

Joy. Midnight trip to Pittsburgh with the salesman.

Actually it was fun. Not much traffic at night.

Landing pattern at 160mph in between DC9s into Pittsburgh at about midnight. And they didn't like 160 at all. This was scary.

Quickest turnoff onto a taxiway I've ever experienced. Of course the taxiway may not have been one. We didn't care.

tom K0TAR

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Sal, A relative number by any other name would smell as sweet. The reccomendations for my box is about the same but it works well below that at least according to what I measure withe the cable box. BTW it just says 'db'. dBm was an assumption on my part..

Jimmie

Jimmie

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Jeff, I installed TVRO systems for several years and used a lot of F connectors. Suprisingly the ones I found that worked best were the ultra cheap ones that only took a pair of pliers to fasten These were the ones with the separate crimp rings. Used with some good quality heat shrink tubing this eliminated most of the problems you mention. I dont know why these connectors went away, my only guess is that someone wasn't making enough money on them.

Jimmie

Jimmie

Yech...

Please try this test. Insert such a crimp type F connector and cable into some useless piece of equipment with a type F jack. Pull on the cable hard. In my experience, it doesn't take much to make the cable and connector part ways. Repeat with a screw on connector. Now, repeat the experiment using a properly assembled compression type F connector and cable. It takes considerably more brute force to break the connection. I think the official minimum pull test is 55 lbs, but I'm too lazy to Google for it now.

Hiding the workmanship under shrink tube is not very functional. It will have little effect on the pull test.

Most of the cable leakage problems I've seen (and found) were due to crimp type F connectors coming apart or badly crimped. That includes both the hex shaped crimp, and ones held together with a crimped ring.

Bad:

Worse:

Good:

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Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Quote "Maximum Drop Length 300 Feet"

Now that's what I call good service.

See above. Obviously others can. And yes, I have designed RF broadband power amps. Lots of them. Not just lashing up boxes but the actual transistor level circuitry including layout guidance for the nasty stuff.

Fact is, if a cable company isn't competent to do a 170ft drop they should decline the job. Otherwise it is a screw-up, plain and simple. In our area they'd lose their shirts to the satellite guys because there are many houses like ours where there is no reasonable way to get from the street to the house with a 100ft limit. We have around 200ft that's still there from the early 90's and the previous owner said cable TV worked just fine for them. We are not subscribed because TV ain't that important to us.

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Regards, Joerg

http://www.analogconsultants.com/

The Box is a CISCO RNG100 Only data I know how to get is; Tuner 537.00 Mhz 2dbmv TDC 75.25 Mhz 5dbmv RDC 20.00 Mhz 30.0dbmv Yes 30.0

On the road, will check in this evening. Mikek

Still easier than having to use blasting caps to find the ends of a broken conduit under the finished concrete floor in a new RADAR site. An old fish tape & blasting cap pushed as far as it would go and BOOM!!!. Then repeat for the other end. Then they used a jackhammer to break out the concrete between the huge floor divots to install new conduit. The electrical contractor had failed to tie the conduit to the rebar & wire mesh before the pour. :)

Or driving ground rods through permafrost in Alaska. We drove 60' of rod and used three tanks of Acetylene to heat the rod to get it through the ice layer outside a military radio & TV station at Ft. Greely.

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You can't have a sense of humor, if you have no sense.

You've got me beat.

I am glad I didn't have to use blasting caps as TDR. But it does sound kind of fun if you didn't have delivery pressure on top of it.

Sounds like good work. But not up the Giant Rat's standards, I'm sure.

Interesting that he portrays himself as young and uses that reference. Very curious. Maybe he's old and a failure and not young and a failure as he claims.

tom K0TAR

Those were the lowest grade, next to screw on fittings. They had the highest leakage, and shortest service life of all the connectors I ever tested. Did I mention that we bought 50,000 feet of RG-59 & RG-6 per month for cable installs? We were using the Raychem for new work & repairs in the mid '80s. They were the best we could find, both for drop, trunk & feeders. They didn't need a boot, and you would break the cable before a connector would pull off, if installed properly. We had to keep a close eye on radiation to prevent one of the midband channels from interfering with airplanes. 95% of the problems were those half assed separate ring, three cent connectors.

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You can't have a sense of humor, if you have no sense.

He was a cable grunt when Time Warner built Cube in Cincinnati, so I'd say that he's at least 50 and still a very angry failure.

That RADAR site was at Ft. Rucker, and the problem was in the area reserved for the new IFF hardware in the mid '70s. Weathervision was assigned to the space while I was there, but were were in the process of moving to another building when I was told I had orders for Vietnam. I ended up in Alaska instead. Two weeks later that AFRTS station in Vietnam was overrun and the engineers killed. They shipped parts of the transmitter that survived the gunfire to the station in Alaska. :(

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You can't have a sense of humor, if you have no sense.

It's the same as the Cisco Explorer 1540C with some features removed by Comcast.

How to get into the diagnostics: Press and hold SELECT on front of unit until the MAIL light starts to flash, then press INFO. Or Press and hold PAUSE on remote until MAIL light starts to flash (around 10-15 seconds), then press PAGE-UP (-). On some remotes, PAGE (+) might need to be used instead.

I'll guess(tm) that TDC is downstream power, and RDC is upstream power. (20MHz is in the frequency range used by upstream path).

30dBmV is acceptable as the upper limit is about 55dBmv. Remember, this is dB's above 1mv into 75 ohms, not dB's above 1mw into 50 ohms. dBm = dBmV - 48dB So, your 30dBmv is really -18dBm

The downstream values are also in the ballpark. See:

The numbers are for cable modems, but the levels should be similar for DTV. The typical delivered values should be: -10 dBmV to +10 dBmV "Recommended". -11 dBmV to -14 dBmv / +11 dBmV to +14 dBmV "Acceptable". -15 dBmV & +15 dBmV "Maximum".

5dBmV is fairly is good enough and should result in a usable picture.

See if you can excavate the SNR numbers. Maybe there's RF garbage on the systems (oscillating distribution amp, ingress, whatever, etc).

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# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com               jeffl@cruzio.com
# http://www.LearnByDestroying.com               AE6KS

Sounds correct. He's got problems alright.

Sorry to hear that. Had friends that survived intact but were still damaged goods from that war.

tom K0TAR

40 lbs outdoors, 30 lbs indoors.

6.2.2 Axial Pull Force: The male ?F? pin type connector, when attached to cables manufactured to SCTE approved standards, shall withstand a minimum axial pull force of 40 lbs for outdoor and 30 lbs for indoor applications when tested per ANSI/SCTE 99 2009, Test Method For Axial Pull Connector/Drop Cable.

I doubt that the crimp connectors could pass the test.

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# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com               jeffl@cruzio.com
# http://www.LearnByDestroying.com               AE6KS

< snip >

Good story. It brought to mind a promotional video I saw for a company that had a process called explosive bonding (of dissimilar metals). They must have been too cheap to rent lights, so they did the demo outside on an old wooden table. It was two guys in overalls and, I swear, they could have retitled it "Gomer and Bubba Find Some Dynamite" and nobody would have noticed.

"Sal"

No one wants to let rednecks with dynamite indoors. ;-)

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You can't have a sense of humor, if you have no sense.

Sorry Jeff but I never used my connectors to support my cables. You may be right but completely irrelevant to me. To me F connector and good connection shouldn't even be used in the same sentence. They are what that are, cheap connectors at best that uses the center conductor of the cable for a contact. Now that is Yech. Heat shrink has nothing to do with the pull test or hiding poor workmanship but it does help keep corrosion down which is the biggest problem with F connectors. Ive never seen one pull apart except in the shoddiest of installations. One of the best things I have found to insure you maintain a good connection is to apply something like DeOxit to the connectors when you assemble them. Best done while all the parts are new.

Jimmie

You are correct that the problem is in the hex crimp and part of this is because they started making the crimp made on to the connector. The other part is that you have to have a special tool to crimp them. All the pictures that you showed are require a special crimp tool. If these tools are worn or dont fit the particular plug/ cable combination you will get a bad crimp. The old style that is probably

40 years old now that you could crimp the little ring with a pair of pliers worked the best. Unfortunately you can no longer get them, well I do have a few.

Jimmie

There little wrong with good quality F-connectors. They are generally good enough for what they were intended for. Problems are usually down to who installs them, and how.

For personal outdoor use, I always give any connectors a squirt of WD40

- both during and after installation. [I guess DeOxit would be similar or better.] After cleaning off most of the WD40, I then seal with self-amalgamating tape. Obviously, heatshrink would be better, but for me, is usually less convenient.

Mechanically, even screw-on Fs can be hard to dislodge, provided just the right amount of braid is trapped under the screw thread. However, I suppose that sometimes they might not provide the ultimate in screening.

In the UK, in the large CATV networks, crimped connectors are well and truly a thing of the past. Anyone using them (even the good ones) would be liable to be hung, drawn and quartered, and then severely punished.

The standard connector is of the 'Snap and Seal' type (and similar). In themselves, these are pretty well watertight, and the screening is excellent. It should be almost impossible to pull one off the cable.

However, it is unusual for F-connections to appear naked in the open air. The final RF distribution to the home is invariably from a street cabinet which houses an optical node or an RF distribution / line extender amplifier feeding a bank of taps/splitters. The 'traditional' cascade of in-line taps has not been used for a very long time. Under these relatively benign conditions, the F-connectors probably suffer much less from corrosion than those used on taps hanging on aerial messenger wires, USA-style. Nevertheless, there are various purpose-made short 'chunky' rubber sleeves which can be installed first on the tap ports before the cable connectors are screwed on. These seal the screw threads. Personally, I would have liked to have seen a bit of WD40 used but I never managed to drum up much enthusiasm for this as an approved practice.

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Ian