Terk Tower Antenna

[mashaffer]

Since I don't seem to be able to eliminate the RF interference generated by the plate amp in my sub (seems to turn input cable into transmitting antenna) I thought that I might try using a remote antenna mounted in the attic.

Has anyone tried one of these Terk tower antennas ? For twenty bucks it seem worth a try.

The only other solution I haven't tried yet is converting a computer cord with the ferrite wart to carry my input signals to the sub to reduce the RF radiation however it would be nice to get better overall reception anyway.

mike

[Glowbug]

Have you put ferrite beads on the input cable to reduce common mode noise?

[mashaffer]

No I haven't. I have a cable from a junk computer monitor that has a ferrite built in so I thought I might try just puting RCA connectors from my parts bin on it and try that thinking that it would be the same thing but I haven't tried it yet. If I wasn't so cheap I would probably just run down to Rat Shack and pick up a $6 ferrite. I may still do that to save the time.

BTW. Do you think that the ferrites on old computer cables would have any chance of being as effective as the snap ons?

mike

[mashaffer]

Well I did run out and get a ferrite core and it didn't really do very much so I am still looking to do something with the antenna. I guest I could get a 300-75 transformer and relocate my diapole antenna and run a long 75 ohm run back to the stereo. That would be a cheaper first try. Stronger stations do have less problems with the interference so it seems worth a try.

mike

[DigitalJunkie]

Is your sub's plate amp a class D /switching type?

My question is,Why is the plate-amp radiating RF in the first place? Maybe it's oscillating?

[mashaffer]

Originally posted by DigitalJunkie
Is your sub's plate amp a class D /switching type?

My question is,Why is the plate-amp radiating RF in the first place? Maybe it's oscillating?

I believe it probably is class D (Cheap AR 8" sub is unlikely to use an expensive amp). If it turned out to be a conventional amp with a switching supply I would just build a proper PS and be done with it but if it is class D as I suspect then replacing the amp is probably the only reasonable course of action.

It has had this problem since I first got it. In retrospect I should have sent it back as defective. With very strong FM stations (very few of those around here) the interference becomes unnoticable.

Probably the cheapest real solution is to buy a different plate amp but I am not convinced that class D is such a great idea.

mike

[davidsrsb]

Your sub is violating FCC class B then.

The ferrites on computer monitor cables work better than the snap on ones because the inside hole is only just big enough for the cable.

[cicero32]

Dear friend,
if there are RF interference in the room it's not a good idea use an amplified antenna.This type of antenna it's usually broadband and high gain.I think you will pick any kind of noises present or not.
Better a passive aerial on roof and a better cable with ferrite core and an earthed metal box for sub ampli.

ciao cicero32

[mashaffer]

Thanks for the input folks. Cicero, my plan was to place the antenna in the attic over the garage but I found that just connecting my diapole to a long length of 300 ohm cable and moving it to the other side of the room helped considerably and putting it out on the back porch worked fabulously well. I think I will just run the 300 ohm cable into the garage attic and use my existing diapole that way. Should probably solve the problem.

Again, thanks to all for your help.

mike