A ground loop in your AV system caused by antenna connection or TV cable is very common if you have your computer connected to the same system. This type of ground loop problem can be solved by using suitable isolator between your AV system and the antenna cable. The simplest way to get rid of the hum is to disconnect the antenna cable from the AV system. If you still want to watch cabe TV or listen to your radio an keep the system hum free then you have to install isolators to all those antenna cable connections your system has.
Antenna isolator is very convient way to solve antenna connection related ground loop problems. Unfortuantely isolator has some drawbacks: attenuation and possible poor suscpectibility to RF interference. All antenna isolators attenuate antenna signals small mount and (around 1 dB) if your antenna signal is already marginally low you can see noticable picture quality decration. If the antenna signal is in recommended antenna signal range then small attenuation should not cause any noticabe decration to the picture quality. Because the isolator cuts the continuous shielding in the antenna cable then this arrangement can make you antenna cabling more suspectible to the radio frequency interference. If the interference is of any problems depends on the construction of the isolator and how much interference is near your equipments.
Antenna isolatiors are manufactured commercially and but you can also make your own if you know something about electronics.
Here is list of some commercial product made for antenna isolation and ground loop elimination. I have tested only some of the products listed below (JEBSEE EU-634, J A-A Junction). I have no information how good other products are.
Commercial antenna signal isolators
- Cable Master Cable Isolator from Electronic Specialists
- GroundGuard form Tributaries Cable
- ISO-MAX Model VR-1FF from Jensen Transformers
- J A-A Junction häiriöadapteri televisioon from SUOMEN RADIOAMATÖÖRITARVIKE OY
- The MAGIC Box from Mondial Designs Limited
- Unhummer from Clearview Engineering
Where to get isoltors in Finland
- SUOMEN RADIOAMATÖÖRITARVIKE OY sells J A-A Junction häiriöadapteri televisioon (around 50 mk)
- Yleiselektroniikka has JEBSEE EU-634 CABLE/VCR GROUND BREAKER FEED THRU SURGE PROTECTOR (around 60 mk)
- Partco Oy sells also antenna isolators (around 50 mk) (Teuvo Pakkalan tie 9 Hki Puh: 09-5876960), order name: ANT EROTIN