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Pannell
03-14-2019, 10:12 AM
I just had my roof replaced on our 2011 BC 3650 and now I have no TV reception from the antenna to the bedroom TV, I have pulled the booster plate down and also the coax from the antenna down inside the bedroom and I ran a coax from there to the booster and TV works great so I have a bad cable that goes thru the ceiling. Maybe they put a nail into the coax. I tired to pull on the cable but there is no play at all so pulling a new cable thru is not an option. The ceiling does have Styrofoam type insulation, not sure if it laminated like the walls are. Thinking about dropping a ceiling panel to run new coax, its like 5' away. Any suggestions?

jbeletti
03-14-2019, 10:35 AM
Hi Kim,

Bummer on the coax. Sounds like the re-roofing was contributory to this issue. I would not pull down the ceiling panel. Reason being is that it's glued to the roof structure using a lamination process. I would simply consider running the new short length of coax on top of the new roof and drill a hole down through the roof where it needs to re-enter.

You can choose from a variety of entry plates for the coax where it penetrates the roof. Use a few clips to secure the coax to the roof and use plenty of Dicor lap sealant on the fasteners and entry hole/plate.

wdk450
03-14-2019, 11:33 AM
To further test he coax, with BOTH ends disconnected put a DVM in the ohmmeter/continuity function across the center pin to outside shield of the cable. You should read infinite ohms/no continuity. Now use aluminum foil or an alligator jumper to put a short across one end of the cable. Measuring the other end of the cable you should now read 0 ohms/continuity from the meter. If the cable tests good on these DC tests, you can then try installing new F connector ends on both ends of the cable. There are crimp on or screw on types available at home improvement centers.

Your cable could have low frequency response issues due to physical deformation of the cable, but this is the least likely of the possible problems, and requires sophisticated analysis tools to detect. Did they remove the roof substrate wood below the rubber membrane? If not, the coax should be intact. Trying to run a new coax line through the roof insulation is extremely difficult.

Good luck to you!!

cookie
03-14-2019, 11:45 AM
Before trying any drastic removal or adding holes my first step would be to test the coax as Bill mentioned.
Then, since the roof insulation is foam I would do my best to try and jam a stiff wire through the foam insulation from the antenna to the booster. This would be my first and probably only method to run a new coax.
But testing and replacing the F-connectors on the coax would be the first step.

Peace
Dave

CDN
03-14-2019, 01:58 PM
Cookie has a very good option. It will make a mess but I have fished the foam to replace an antenna coax in a SOB once. Used a actual fish tape, nice and stiff.

Brian

david-steph2018
03-15-2019, 07:27 AM
Before pulling the old cable out see if it is 1 piece. If it is see if there is a way to tie the new cable to the old, using a connector or tape and gently pull both thru at the same time. if you are lucky, and gentle, you may be able to pull the new cable thru while pulling the old out.
It is worth a shot at it.

Good luck

Pannell
03-15-2019, 08:58 AM
Thanks for the help. The existing cable will not move at all and the RV service guys that did the roof applied a new layer of luan over top of old after they replaced 3 damaged sheets so Im thinking the cable might be damaged but I will try to test it like Bill said. Thanks again.

wdk450
03-15-2019, 08:17 PM
I rarely use, but keep in the trailer, a fiberglass rod cable "fishing" set from Harbor Freight Tools: https://www.harborfreight.com/3-16-inch-x-33-ft-fiberglass-wire-running-kit-65326.html

BTW, Home Depot has a dedicated coax tester that puts a specific load (I would guess 75 ohms) on one end of the cable with a special F connector cap, and then the tool measures the resistance at the other end. Around 75 ohms is "GOOD", Well above 75 ohms is "OPEN" and well below 75 ohms would be "SHORT".
https://www.homedepot.com/p/Klein-Tools-Coax-Explorer-2-VDV512-100/303834923

Again, this just measures the DC characteristics of the coax, and not the VHF-UHF AC frequency bandpass.

jbeletti
03-15-2019, 09:14 PM
Bill - I can't let you have all the technical fun :) Back in my prior career, we would use a TDR (time domain reflectometer). We could see reflections on the display and it would tell us the distance to the reflection. When you got good at it, you could tell the difference between a connector, a splice and problems. But I digress. We don't have access to that sort of gear in this industry.

CDN
03-15-2019, 11:11 PM
Bill - I can't let you have all the technical fun :) Back in my prior career, we would use a TDR (time domain reflectometer). We could see reflections on the display and it would tell us the distance to the reflection. When you got good at it, you could tell the difference between a connector, a splice and problems. But I digress. We don't have access to that sort of gear in this industry.

I happen to have an inexpensive TDR a Triplet that actually does a pretty good job, found a screw through a coax in the bighorn within a foot.

jbeletti
03-16-2019, 12:44 AM
I happen to have an inexpensive TDR a Triplet that actually does a pretty good job, found a screw through a coax in the bighorn within a foot.
Cool! You really must need one of these to have purchased it.

wdk450
03-16-2019, 09:30 AM
Bill - I can't let you have all the technical fun :) Back in my prior career, we would use a TDR (time domain reflectometer). We could see reflections on the display and it would tell us the distance to the reflection. When you got good at it, you could tell the difference between a connector, a splice and problems. But I digress. We don't have access to that sort of gear in this industry.

I first saw a TDR tester in the late '60s when I was in the Naval Security Group and we had these large array Wullenweber direction finding HF antennas that were composed of about 60 high band HF and 60 low band HF vertical antennas in a 1/4 mile (?) circle with a bunch of 100 foot telephone poles between the 2 vertical systems with a grounded curtain hanging wire array between the 2 antenna circles. A pretty impressive antenna system with a coax connection to each of the vertical antennas. A high speed spinning goniometer switch connected the wide band receivers to each of the antennas in millisecond times. That plus state of the art computers (for that time) analyzed the incoming signals and computed directional vectors. Then those signals were compared with a bunch of other stations ringing the Atlantic and Pacific oceans electronically to get absolute radio direction finding. I haven't disclosed anything not known to the general electronic community, and ALL of those NAVY HFDF stations ringing the oceans are now closed in favor of more advanced technologies.

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