I went under the roof and saw that the coax cable coming from the satellite antenna neither the one coming from the FM antenna are grounded. Both cable run along the same path. Odd that one would picked up mains hum but not the other.
Yes , thats strange. Maybe cable have breaks, connection points , water corrosion , which affected shield foil . Many TV cables have alu foil , very weak with moisture .Did you tried to check FM antenna cable connectivity with multimeter? Probably at antenna end , in connection box , cable is shorted , so in other end at jack you should see maybe few ohms between center and shield . Most passive antennas have dc shorted by it's construction, by loop connection method.
Unfortunately no : the antenna connection box is to high on the roof to be accessed without securing equipment.
Meanwhile, I have put another type of tuner in the hi-fi. I will see if it get preamp and amp as warm as the other one.
Meanwhile, I have put another type of tuner in the hi-fi. I will see if it get preamp and amp as warm as the other one.
Try current FM tuner without antenna cable first, use piece of wire instead of antenna for test .
I think this is the wrong track. Nothing but RF is going to get through the front end, and no RF is going to get out of the IF strip, let alone the audio section of the tuner, let alone the preamp.
Can this temperature rise be measured? It's such a bizarre and unlikely event as to require some numbers to believe.
Every country has different rules, but in America (not famous for modern safety rules, as contrasted with EU) all antenna and cable wiring is required to have shields Earthed (to the same Earth as mains power) before entering the building. It's very surprising that rules in EU are less stringent than in America. You should really do it anyway, for safety. Might also get a little better lightning immunity.
All good fortune,
Chris
Every country has different rules, but in America (not famous for modern safety rules, as contrasted with EU) all antenna and cable wiring is required to have shields Earthed (to the same Earth as mains power) before entering the building. It's very surprising that rules in EU are less stringent than in America. You should really do it anyway, for safety. Might also get a little better lightning immunity.
All good fortune,
Chris
You're right. I am deeply unsatisfied with the work done by the installer. When I get all the parts to redo the wiring of the antenna, I will make some experiment and monitor case temp with a thermocouple in various situation.
I have had a few inexplicable failures of hi-fi stuffs throughout the years. I wonder if remote lightning strikes (I always disconnect everything from mains and antenna in case of weather storm when I'm at home, but you never know) or static discharges could have been the culprit.
I have had a few inexplicable failures of hi-fi stuffs throughout the years. I wonder if remote lightning strikes (I always disconnect everything from mains and antenna in case of weather storm when I'm at home, but you never know) or static discharges could have been the culprit.
If you have an outside antenna that enters the house, the whole thing has to be grounded by a solid wire to a dedicated ground point. Usually before it enters the house. That is standard in Europe.
If yours is not grounded, connect it at least to the nearest central heating or water pipe. This is not allowed today, because of all the plastic used, but did a good job for a century. See, there are two things: One is the technical component and the other the legal side, where the norm has to be fullfiled 100% as written in some book.
If your house burns down and the missing antenna ground was the cause, your insurance won't pay. If your house does not burn down after a thunderstorm, because your "wrong made grounding" prevented it, no one will ask why. So better an old fashioned, wrong but working ground, than none.
Whether that will cure your problem of the hot FM is another page.
My serious advice: Read the rules for grounding antennas in your region and check your installation. If it does not comply, fix it or have it fixed.
Sometimes the ground pole connection suffers from corrosion. I had that twice at my house, where the clamps had simply corroded away. Ground poles are metal rods hammered deep into the ground. Google how they look in France and walk around your house to find them.
If yours is not grounded, connect it at least to the nearest central heating or water pipe. This is not allowed today, because of all the plastic used, but did a good job for a century. See, there are two things: One is the technical component and the other the legal side, where the norm has to be fullfiled 100% as written in some book.
If your house burns down and the missing antenna ground was the cause, your insurance won't pay. If your house does not burn down after a thunderstorm, because your "wrong made grounding" prevented it, no one will ask why. So better an old fashioned, wrong but working ground, than none.
Whether that will cure your problem of the hot FM is another page.
My serious advice: Read the rules for grounding antennas in your region and check your installation. If it does not comply, fix it or have it fixed.
Sometimes the ground pole connection suffers from corrosion. I had that twice at my house, where the clamps had simply corroded away. Ground poles are metal rods hammered deep into the ground. Google how they look in France and walk around your house to find them.
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Are the power transformers getting warmer as well in the preamp and power amp?
In this case it could be that there is an issue with the power supply of the tuner (dirty).
It could be checked with an oscilloscope on the secondaries of the preamp's transformer then.
In this case it could be that there is an issue with the power supply of the tuner (dirty).
It could be checked with an oscilloscope on the secondaries of the preamp's transformer then.