Masthead Amplifier

[jonnytabpni]

Hey folks. I'm sorry if this is in the wrong section.

We have had an antenna setup for a good while now. We have two antennas. One of them goes into a Masthead amp at the pole. Then out of this amp into a diplexer (also at the pole) and the other antenna goes stright into the diplexer. Then out of the diplexer down the long cable into the lounge into a PSU. Then out to the TV.

Our reception from the antenna which needs the masthead amp wasn't working. So I went out and bought a new PSU for it (different brand). Low and behold it worked...for a while. Then the short circuit protection kicks in. I have remade the coaxial connections in the lounge multiple times to no avail...after about 15 – 20mins, the short circuit protection kicks in.

What do you reckon is going on? Some water in the masthead amp/diplexer at the pole cuasing some form of a short?

You help is appreciated.

Cheers,

Jonny

P.S. On the new PSU, there is a grren LED which changes to RED when a short has been detected. In my case, the light slowly changes to red (being yellow in the middle...)

Note to mods, if you feel this post should be in another section, please move it cheers

 

[crutschow]

The diplexer may look like a resisive load to the PSU. Measure the resistance across the coax. If it's around 50 ohms, then that's what's loading the PSU. You need a diplexer that's designed to carry power to the masthead amp.

 

[jonnytabpni]

thanks for the advice however it was installed by a professional company about 8 years ago and has been fine up until a couple of months ago.

What should the resistance accross the coax be?

Cheers

 

[crutschow]

What should the resistance accross the coax be?

It should be just the resistance of the amplifer power connection. I would estimate that to be at least a few hundred ohms.

 

[RadioRon]

Its quite possible that there is water inside the coax and that is looking like a low resistance to the PSU. Only fix is to replace the coax if thats the case, or wait until summer and for the coax to dry out (if it ever does) then seal up the ends a bit better against the weather.