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Old 14-Feb-2015, 7:50 PM   #1
Martin Malley
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Join Date: Feb 2015
Posts: 7
Was good, now not so good

Antenna: 100 mile directional (I think it is a Channel Master 100). 10 plus years old.
Have a distribution booster, but no pre-amp. Signal splits to four TVs.

Here are my scan results:
http://www.tvfool.com/?option=com_wr...2c152df3ad3f50

So this setup worked great on the roof for 10 years. Moved it to a tower (slightly taller) a year or two ago and still worked great. I was getting ABC, NBC, CBS, PBS and Fox out of Columbus, Ohio.

The signal for CBS and Fox started to get intermittent and now I have only NBC and CBS. I re-aimed the antenna last weekend and all the channels came in again, but Fox and CBS were spotty. A couple of days later I am back to just two channels.

I also took out a grounding block I had before the cable went into the house. I ran the cable directly to a TV and the channels came in. So I thought that block was the problem, but now I have no idea.

Does anyone have any suggestion? I keep wondering if the connection to the antenna is weak. I can see the wing nuts are rusty, but as they are out on the end, I can't re-do them without taking the antenna down.

Would I be better off with a multi-directional?
Is 51 causing issues with 6 and can I block one to get the other?
Do I need an FM choke or something?

Thanks in advance for any ideas!

Last edited by GroundUrMast; 14-Feb-2015 at 7:57 PM. Reason: repaired TVFR link
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Old 15-Feb-2015, 6:30 PM   #2
signals unlimited
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It is highly unlikely that it's FM interference as it only effects VHF. Any co or adjacent channel problems would not come and go. If you bypassed the distribution amp and tried a known good coax from the antenna via a matching transformer, the matching transformer is the most likely culprit. I have found that when using standard crimp connectors, even with a boot, that the boot can hold water and waste the connector. I would go up the tower with a new matching transformer, a snap and seal connector and tools, replace both and your problem should go away.
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Old 15-Feb-2015, 10:42 PM   #3
Martin Malley
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The fear!

I was afraid someone would say something like that. I tried to weather-proof the connection with tape (lame, I know). The biggest problem is there is no way to reach the connection without removing the antenna. That's going to be a bit tricky.

Just to be clear: the matching transformer is the tube with the leads coming out that connect to the antenna on one end, with the coax connection on the other. How do I find a new one will that match my existing antenna if I'm not sure of the exact make and model?

Is there anything I should do to weather proof the leads attaching to the antenna?

Can I run wires from the antenna to the top of the tower and have the transformer there so I can replace it, if need be, in a couple of years without having to take the antenna off the post?

Should I get a new grounding block where the cable enters the house? I know one side of the block was oxidized. How can I weather proof that or is there one built for outdoors?

Thanks again for the help and advice.

Last edited by Martin Malley; 15-Feb-2015 at 10:51 PM.
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Old 15-Feb-2015, 11:47 PM   #4
signals unlimited
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You got it!

All TV antenna matching transformers are technically the same. They match a 300 ohm balanced antenna (like yours) to a 75 ohm unbalanced transmission line (your coax). Lately there have been some very poor quality MT's out there.
The one I use and trust is made by Channel Master. That is a safe choice. Mount on the antenna. I do nothing to the wing nut connection unless it is in questionable condition. If so cover it with silicon calk. I use Ideal compression connectors and throw away the boots and tape. The tools for striping and installing are available at Lowes. If you use these connectors and mount your ground block sideways, not up and down, you will probably never have another problem.
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Old 16-Feb-2015, 12:01 AM   #5
Tim
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Quote:
Originally Posted by Martin Malley View Post
I was afraid someone would say something like that. I tried to weather-proof the connection with tape (lame, I know). The biggest problem is there is no way to reach the connection without removing the antenna. That's going to be a bit tricky.

Just to be clear: the matching transformer is the tube with the leads coming out that connect to the antenna on one end, with the coax connection on the other. How do I find a new one will that match my existing antenna if I'm not sure of the exact make and model?

Any matching transformer from a well-known manufacturer with 300 ohm wire terminals on one end and 75 ohm coaxial connector on the other end will work.


Is there anything I should do to weather proof the leads attaching to the antenna?

After the connection is clean and securely tightened you can seal the connection with some RTV silicone sealant. I use Permatex Blue RTV Silicone gasket maker #80022 because it is readily available at the local auto parts store and is inexpensive.


Can I run wires from the antenna to the top of the tower and have the transformer there so I can replace it, if need be, in a couple of years without having to take the antenna off the post?

It would be best not to do that. The transformer will work much better directly at the antenna.

Should I get a new grounding block where the cable enters the house? I know one side of the block was oxidized. How can I weather proof that or is there one built for outdoors?

If you have any doubts about the grounding block, go ahead and replace it. They are relatively inexpensive.

All outdoor antenna connections should be weatherproofed. As I mentioned before you can use RTV silicone sealant on screw type connections. For coaxial connectors I wrap them with silicone fusing tape which is usually available at your local home improvement store. I do not use rubber boots as I find the fusing tape is much better at keeping the connection water proof.


Thanks again for the help and advice.
Please see my comments above in bold type. Good luck!
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Old 21-Feb-2015, 6:02 PM   #6
Martin Malley
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While we're waiting

While I'm waiting for the weather to break, so I can gather the parts and redo my connections, I have another question/piece of the puzzle.

After my last post, I was watching the TV in the kitchen (old school with a TV digital adapter) and all the channels were coming in just fine! The other three were only getting the two or three strongest.

I tried a bunch of combinations on the distribution amp to see if I could get our TV card on the computer to get all the channels (to dvr), but no joy. And I lost the channels I did have.

Does this make any sense to anyone out there? Is there any way to get the output of my distribution amp with a multimeter?
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Old 11-Apr-2015, 9:39 PM   #7
Martin Malley
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Well I finally got the antenna down and there was definitely water getting in the cable/transformer connection. I'm off to get my silicone, but I saw something that seemed strange. The two hoops that come down to the connection posts are not connected. Are they supposed to be? It sure seems like they should be.

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Old 11-Apr-2015, 11:14 PM   #8
Tim
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My assumption is that your balun was connected to the two wing nuts towards the bottom of the photo. If so then it is my guess that the ends of both "hoops" should be connected where those screws rusted out. If you file off the rusty top portion you can probably remove the wing nuts from the screws and then grasp the screw with some vise grips and rotate and pull until they come out. If you replace them with some stainless steel screws they won't rust out over time. You could also try tapping upward on the screw to see if it will come out. Main thing is to be careful and not break that plastic. Maybe someone who is more familiar with that particular antenna can weigh in on the subject, but it looks easily repairable to me.
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Old 12-Apr-2015, 12:01 AM   #9
Martin Malley
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I went out to look at the bolt size to get a replacement and it dawned on me the balun is supposed to (and I'm sure was at one time) drop down and onto the bolts where the wing nuts live. How I missed that when I moved the antenna is beyond me! And, when I first put this up I was getting all the channels without the baluns connected!
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Old 13-Apr-2015, 12:25 AM   #10
Martin Malley
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So I get the antenna back up, crimp a new end on and test with the multimeter. Seems to come up with a short. So I take the entire thing down, start to remove the cable from the transformer and the RCA transform threads start spinning. Piece of junk.

Then I started thinking that the outside of the cable should now be connected to the wire through the antenna. So did I just waste a whole lot of time?
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Old 13-Apr-2015, 1:48 AM   #11
rabbit73
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Location: S.E. VA
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Quote:
Is there any way to get the output of my distribution amp with a multimeter?
No, you need a signal level meter that is designed for that job. Some TVs have a relative signal strength meter.

Quote:
So I get the antenna back up, crimp a new end on and test with the multimeter. Seems to come up
with a short.
A test on an antenna or balun matching transformer with an ohmmeter can be misleading.
What looks like a short with the DC test current of an ohmmeter, might be OK for RF.

Quote:
So did I just waste a whole lot of time?
No, you didn't waste a lot of time.

You gave it a good try, but your old antenna is too far gone, and is in very bad condition.

As you said in the title: "Was good, now not so good."

Even if you could figure out how the parts should be connected together, you would still need to drill out
the rusty connections, clean the parts, and replace the screws.

It's time to replace your antenna.

The channels that you want from Columbus are all UHF, so you need to buy a new antenna only for
UHF like the Antennas Direct DB4e.
__________________
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Last edited by rabbit73; 13-Apr-2015 at 2:15 AM.
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Old 18-Apr-2015, 7:41 PM   #12
Martin Malley
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Well, with all respect to Rabbit73's advice, the antenna, baluns properly connected to the transformer, is back up. The best we did before was about 15 channels. The initial scan came up with 40! I'll have to dig through the map and see where they are all coming from, but one is from Zanesville, in about 180 degrees the opposite direction, and Athens, 90 degrees the wrong way. Hooray!
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Old 18-Apr-2015, 8:32 PM   #13
rabbit73
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Thanks for the update with the good news. Good job on repairing the antique antenna.

What was good, is now good again!
__________________
If you can not measure it, you can not improve it.
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