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Old 6-Aug-2015, 12:50 AM   #1
Kaptkimbo
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tv reception Middleville, MI area

I recently replaces my antenna that I had for 20 years. Last summer it was struck by lighting. I've replaced all the coaxial cable from the antenna on done probably 75-85' run. I installed solid signal 8 bow antennas and couldn't pick up reception from stations I can see from my roof. I should have about 20 station line of sight. I installed a Channel Mater CM-77782 preamp and pulled in 13 stations. last week all of the sudden I have no reception. I've checked and there is power from the insert at 22 v DC. Not getting a good reading around the preamp. Could the pre-amp be bad? (I installed it briefly for an hour or so last year to try and get better reception but it didn't work with old antenna) I was thinking of trying a variable gain pre-amp so I don't over power my sigansl.

Any help would be greatly appreciated
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Old 6-Aug-2015, 12:57 AM   #2
rabbit73
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Welcome to the forum, Kaptkimbo:

Please post a link to your tvfool report so that we can see what the signals look like at your location. Go here (>> Click HERE <<) and enter your exact address, which will not show:
http://www.tvfool.com/index.php?opti...tpage&Itemid=1

A generic report for Middleville, MI would look like this, but we need a more accurate report to make a good analysis because you might have some strong signals that would overload a preamp:
http://www.tvfool.com/?option=com_wr...8e03040b7c8563

Which CM7778 is it, the old one with separate inputs for VHF and UHF, or the new 7778 with just one combined input? See attachments.
Attached Images
File Type: jpg Old 7778.jpg (151.1 KB, 389 views)
File Type: jpg New 7778.jpg (31.4 KB, 390 views)
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Last edited by rabbit73; 6-Aug-2015 at 1:17 AM.
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Old 6-Aug-2015, 1:53 AM   #3
Kaptkimbo
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tv reception Middleville, MI area

The CM 7778 is the new one. I couldn't get any signals to my TV till I installed the pre-amp even though I'm close to stations Link to TV fool report...hope this is correct
http://www.tvfool.com/?option=com_wr...8e031ed2eba942
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Old 6-Aug-2015, 11:13 AM   #4
ADTech
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Quote:
I couldn't get any signals to my TV till I installed the pre-amp even though I'm close to stations Link to TV fool report..
You'd have to have a very SEVERE defect somewhere in your system for that to be the case. Your close-by stations are so strong a paperclip should receive them.

You really need to resolve that issue before trying to do anything else. Since you're dealing with a post-lightning strike event, it's prudent to assume that EVERYTHING is suspect until proven to be good. By everything, I include the TV set(s), all cables including fly leads indoors and out, all couplers including any wall plates, any splitters, etc.
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Last edited by ADTech; 6-Aug-2015 at 11:28 AM.
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Old 6-Aug-2015, 6:46 PM   #5
rabbit73
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I agree with ADTech, something is very wrong. You are already in overload territory even before adding antenna gain. WOOD has a NM (Noise Margin) of 72.7 dB.



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

How do I troubleshoot my CM7777 preamplifier to make sure it is working correctly?
http://support.channelmaster.com/hc/...ing-correctly-
Attached Images
File Type: jpg NMChartC.jpg (71.3 KB, 711 views)
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Last edited by rabbit73; 6-Aug-2015 at 6:57 PM.
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Old 6-Aug-2015, 9:19 PM   #6
Kaptkimbo
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tv reception Middleville, MI area

Every thing is new since lightning strike including TV... the mast and ground are the only things remaining....I agree I should be pulling in stations left and right....just trying to determine what is wrong...would a kink in the coaxial cable severely limit the signal? when I put in the new cable I think i may have kinked in pulling through the walls..it seemed OK and have had reception through it till the last 10 days. The cable after the power inserter runs out to a grounding block then another section to the up to the pre-amp then pre-amp to antenna.

When I first installed it I had a splitter (since removed) that had a short run to my daughter TV and she received 20 plus channels. I could see if my multimeter will measure any resistance on the cable run
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Old 6-Aug-2015, 10:14 PM   #7
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A kink might cause a problem that wouldn't show up until later. If the coax is deformed, the center conductor could gradually work its way through the dielectric insulation between the center conductor and the shield to cause a short. This is called "cold flow" and the manufacturer specifies a minimum bending radius for coax to avoid it.

Did you read the Channel Master troubleshooting link I gave you in post #5?

Rather than guess or use a shotgun approach to troubleshooting, I suggest you try to isolate the problem to one part of the system, using the substitution method. The first thing to try would be to replace the coax with a temporary run of known good coax directly from the antenna to a TV through a window or whatever is convenient.

With that test setup you will only have three parts: antenna, coax, and TV. Replace each one with a known good substitute to find out which of the three is defective.
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Last edited by rabbit73; 6-Aug-2015 at 10:46 PM.
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Old 6-Aug-2015, 10:25 PM   #8
Kaptkimbo
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tv reception Middleville, MI area

Thanks...Ill see what the resistance is on that section...maybe I'll replace it...thanks for helping point me in a certain direction.
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Old 7-Aug-2015, 1:13 PM   #9
Tim
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Quote:
Originally Posted by Kaptkimbo View Post
the mast and ground are the only things remaining....
Did you install a new grounding block?
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Old 7-Aug-2015, 9:29 PM   #10
Kaptkimbo
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tv reception Middleville, MI area

yes I replaced the grounding block the old one was fried
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Old 8-Aug-2015, 1:55 PM   #11
Kaptkimbo
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OK...I've attached a small HDTV antenna to my TV and get 10 stations...Think I need to replace the coaxial from the antenna. Is quad steel core copper covered good enough? I can't seem to find any solid copper core locally in smaller than 1000'
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Old 8-Aug-2015, 5:34 PM   #12
rabbit73
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Thanks for the test report. That means the TV is OK if you substituted the coax and antenna. That leaves the antenna and coax run in question.

Quote:
Is quad steel core copper covered good enough?
It should be. Solid copper core is helpful for coax runs longer than 100 ft with a preamp, because it has a lower voltage drop for the preamp power. Your signals are so strong they would overload a preamp. If you want solid copper, Solid Signal makes custom cables:
http://www.solidsignal.com/pview.asp...nal-connectors

Test the new cable when you receive it, and then pull it carefully through the walls.
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Last edited by rabbit73; 8-Aug-2015 at 5:39 PM.
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Old 8-Aug-2015, 5:42 PM   #13
Kaptkimbo
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tv reception Middleville, MI area

Thanks...the solid signal price is pretty reasonable. I think I'll get enough to go directly to antenna w'o using pee amp
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Old 8-Aug-2015, 6:35 PM   #14
rabbit73
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While you are ordering, I suggest you order an FM trap/filter. Your FM signals are even stronger than your TV signals, and might interfere with TV reception. See attachment.

http://www.mcmelectronics.com/produc...804247%2Cd.cGU
https://www.antennasdirect.com/store...on_filter.html
http://comingsoon.radioshack.com/rad...p/1500024.html slow link
Attached Images
File Type: jpg KaptkimboTVF FM est.JPG (119.2 KB, 373 views)
__________________
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Last edited by rabbit73; 8-Aug-2015 at 6:43 PM.
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