Help!! Low level hum from FM cable sgnl

Sounds very much like a ground loop problem. Your cable connection is grounded where it enters the house; if this is not the same physical point as the ground for your power panel feeding the preamp, you typically have a voltage differntial betweenteh two ground points, which is manifested as a hum in the system. Easiest solution typically is to reroute the cable ground to the same physical connection as the power system ground.

Had this problem as well... Monster 1200 (nor any other filter device) will remove this completely. One thing to do is to make the grounds common (keep in mind NEC & local ordinances)(I disagree with the previous post that this is the easiest solution in all cases). The other thing to do is to take $50 to your local high end AV dealer and get an isolation transformer for your cable. This device will pysically disconnect the ground from the cable respective to your tuner. I took the latter approach with wonderful results. Write me if you need help finding this device.

Per J-k a hum-bucker is probably the best answer. But I did find a cheaper solution for my rig. I happened to have on-hand a car-audio isolation transformer. Actually this is two transformers (left & right channels) in 1 package, available from a car-audio shop. Run the audio coax's thru them to your preamps' inputs. These coupling transformers are probably not the nicest thing for your FM audio signal, especially a Dynalab (I have one too) so the hum-bucker is the best solution.

J_k is right. Try an in-line "cable ground breaker", but not from your hi-end A/V store if they charge $50. It will only cost you $15 from a mid-fi store that deals with A/V installations.

I agree with the previous posts about less costly solutions than $50 (Sonance RFGI1)... There are versions as cheap as $8, but there could also be trade-offs with the signal quality. I got tired of trying a box for $8, another for $15, and then I did an audition of this one and it COMPLETELY fixed my problems (I had really loud HUMMMMMMM). I run a 65" HDTV capable TV, and even a minor problem with a cable, connection or signal will drive this thing nuts, The Sonance RFGI1 is a high end component, which also removed hum bars and some other rudeness that the CATV company provides me. You can experiment with all of the above suggestions, and they may work -- If you have more money than patience, or equipment that is finicky of its RF input, try the Sonance. I forgot to mention in my previous post, the monster 1200 and other devices like it have to tie the cable ground to the wall ground to comply with UL device manufacturing rules (all exposed metal must be ground potential). Good luck!!