Aerial antennas have to be grounded for safety. The ground wire drains static from the antenna which would otherwise attract a lightning strike. The ground wire makes it invisible to lightning. But connecting the ground to the earth rod outside the house, then to the signal of your antenna input is a recipe for ground loop hum. Sure enough, I got a loop. After one false start, I have found a
really good fix.
I tried this new humbuster from Jensen this week on my FM antenna lead. Model VRD-1FF. It is a capacitor isolator, not transformer, like their previous VR-1FF was.
http://www.jensen-transformers.com/datashts/vrd1ff.pdf ($45 from avcable.com)
I had been using this one:
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=180-075 ($11 partsexpress.com)
which is transformer based hum isolator intended for cable TV use with the inherent grounding problems with cable. It stopped the hum OK, but it suddenly failed and lowered the signal strength too much, so that hiss and static were heard in stereo, but quiet in mono. Jiggling it while attached to the antenna input would make the hiss stop, but it was intermittant, enough to really piss a guy off. Tightening the connections with wrenches did not fix it.
I started using the Altmann Battery amp with the tuner. In frustration I took out the Dayton isolator in order to stop the hiss and get my signal strength back, and was surprised to hear no hum with battery power - A-HA! No loop! But then I noticed how much better the radio sounded without that transformer in there.
Back to the tube amps and the infernal hum. When I replaced the Dayton unit with the Jensen, the detail, presence and musical wholeness erupted in glorious colors and emotion! A veil was lifted! I ascended into the heavens on a cloud of ecstacy! My Sansui is sooooo happy now!
So yeah, it is better than the other one, a lot better! Jensen plays for keeps and the price difference is well worth it! The clarity of the signal is much better throuigh this filter than the other transformer.
Rich
