Help! Amplifier not working anymore

[tuckgergg]

Hi - I recently installed a large (~14 foot) antenna on top of my garage. I bought a pre-amp/amplifier kit from Radio Shack, have the pre-amplifier installed on the mounting pole under the antenna and have about 120 ft of RG-6 running into my house. The cable runs down the side of the garage, then I dug a small trench in the yard to run it underground. It comes out close to the house and goes into the basement from there. The antenna is grounded at the install point and the cable is grounded going into house.

When I first installed everything, I got about 20 channels and was able to pick up everything that I wanted (live in zip code 16127, antenna pointed ~180 degrees). A few weeks ago, I stopped getting reception and started to investigate. I checked the entire length of the cable (apart from the 30 feet underground) and didn't find any issues. Then, when looking at the amplifier inside, I noticed the light wasn't on, anymore. The strange thing is that when I unplug the input line (the line coming in from the antenna), the power is restored to the amplifier, which makes me think there's a short somewhere.

So, now to my question. Anyone know what could be causing this? Is it a problem with the line? Do pre-amps short out sometimes? Would love to hear if anyone has any opinions. Thanks!

 

[mike123abc]

I would check for a cable short, disconnect at both ends and OHM it out and see if there are any shorts. The preamp probably has automatic protection in case of shorts.

 

[tuckgergg]

Thanks, do you mind elaborating on what you mean by "OHM it"? Sorry, I'm new to this.

 

[mike123abc]

Put an OHM meter on one end of the cable (the center and the ground) and see if there is any short. If a squirrel decided to chew a section of your cable it could be shorted.

 

[FTA4PA]

If you do find a short, it could also be at one of the coax connectors on the ends or possibly water infiltration depending on how well the connections were sealed from weather.

 

[tuckgergg]

I bet it is weather related. I wrapped everything in a pretty good layer of electrical tape, but I have a feeling that may not have been enough. Likely I'll need to buy a better and longer coax cable. Thanks.

 

[FTA4PA]

I use

I bet it is weather related. I wrapped everything in a pretty good layer of electrical tape, but I have a feeling that may not have been enough. Likely I'll need to buy a better and longer coax cable. Thanks.

I use this on all my outdoor connections. Self-sealing, rubber electrical tape - it stretches and seals to itself around just about any connection. I've never had a problem with water infiltration using it: http://www.lowes.com/pd_78453-98-2155_0__?productId=3129711

 

[FaT Air]

RadioShack® Model: 22-182
http://www.wikihow.com/Use-an-Ohmmeter

 

[jayn_j]

Look for about 75 ohms when the antenna is connected to the amp. Then disconnect the amp and measure either end from the center connector to the shell. It should be infinite/open. If the ohmeter test shows a short (0 ohms) then something has caused the center wire to come in contact with the shield. Most likely it is at the connector on the roof. Try cutting off about 2-4 ft and crimp on a new connector. Use FTA4PA's trick for sealing, or just use silicon bathtub calk.

I was a ham radio geek back in the 60s as a teenager. I was also a hormonal teenage jerk like all my friends. One of our tricks when we got mad at someone was to stick a pin through his coax and then cut off the ends. If you did it right it was impossible to find the short and they guy would need to replace the whole cable run. Did it to others, had it done to me. Then I grew up.