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items: cone breakup cures
items: Re: cone breakup cures

cone breakup cures
type: item
description: I am very pleased with a sample build I have of an MLTL (Mass Loaded Transmission Line) as given by the designer who goes by the handle of GM. I get some cone breakup when listening to an over the air FM signal. If I change from stereo to mono the noise goes away. What is the answer to this? The details are: FE127e in the MLTL w/no stuffing or internal damping at all.
creator: lon
date: 2005-05-09T18:38:56-00:00

Re: cone breakup cures
type: item
description: Why do you think it's cone breakup? Sounds more like a tuner problem... Do you have similar prob. with other source (CD, tape)?
creator: robertG
date: 2005-05-11T23:13:18-00:00

Re: cone breakup cures
type: item
description: Erm, I don't think so. So you're saying ot could be the source? Never had the problem on tv. Or cd that I recall. So that would explain why flipping to mono cured the problem? What would cause that at a broadcast source?
creator: lon
date: 2005-05-13T19:08:44-00:00

Re: cone breakup cures
type: item
description: Do all FM stations exhibit this distortion? I was wondering if you're hearing slight multipath distortion. Does changing the position of your antenna help this problem?.....Colin
creator: colinhester
date: 2005-05-16T12:54:42-00:00

Re: cone breakup cures
type: item
description: It's a mystery. My antenna is a straight wire, shielded and indoors. So antenna tuning is not an option. :-/
creator: lon
date: 2005-05-16T13:00:36-00:00

Re: cone breakup cures
type: item
description: Does this happen on all stations? What tuner are you using?.....Colin
creator: colinhester
date: 2005-05-16T13:24:25-00:00

Re: cone breakup cures
type: item
description: Greets! Apparently you can tune a straight wire antenna by adding resistance. Playing around one day I found that terminating a piece of coax I'm using as a TV antenna with a 75 ohm load and then adding R to suit helped quite a bit. I'm sure there's formulas to calc the required resistance for each frequency or BW, but I don't know them. FWIW, 5m ohms works for most of my local TV stations, though I have to fine tune it by moving the coax around since horizontal/vertical orientation affects it. With the other stations, just attaching the 75 ohm termination to a good ground is sufficient. Attaching the shield at the open end to a good ground helps too, or at least it does with my TV. I couldn't tell any difference when I had it attached at the TV's input, but haven't delved into why it would make any difference since the antenna is only ~6.6ft long. Mine is a huge old metal drafting table/desk 'L' unit, but you can just run a 10 ga solid copper wire from an outdoor grounding rod or in-door cold water pipe. After seeing how superior an OTA HD TV broadcast is compared to what the local satellite or cable service offers, I think it's time I learned about antenna design........... HTH, GM
creator: GM
date: 2005-05-16T14:14:00-00:00