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Message |
Bronzepony
Member Username: Bronzepony
Post Number: 58 Registered: 12-2005
| Posted on Monday, May 08, 2006 - 1:39 pm: |
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Last night saw a TVI issue with my Madison-firebird 500 and the computor. Comp. was off and I would come over the speaker in the base of the monitor. Have never done this before. Have not changed any thing. Do conditions affect this? What about TVI on the KLV amps say a 400 or 550? I do have everthing grounded and I am running a filter. Is the KLV a modulator or pure dead key. |
Kid_vicious
Senior Member Username: Kid_vicious
Post Number: 1536 Registered: 9-2004
| Posted on Monday, May 08, 2006 - 5:58 pm: |
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if you mean DX conditions; then im pretty sure the answer is no. i know better than to say definitively. i'd bet something has changed and that you just havent noticed what it was yet. it could be any number of things that are seemingly unrelated. turned mic gain up a bit? plugged either the radio, amp, or computer into a different outlet? different power strip? monitor volume louder than you usually have it? (you may have lowered the volume control on your computer screen, and turned the one on the outside of the monitor up to compensate) the easiest fix is to go to rad shak, and buy a couple of those ferrite beads that clip over the power cable of the monitor. not the big square ones. the round ones. give it a shot. matt |
Chad
Advanced Member Username: Chad
Post Number: 811 Registered: 11-2004
| Posted on Monday, May 08, 2006 - 9:31 pm: |
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TVI is Television Interference caused by the harmonics of the transmitting frequency, unless it was coming over a TV via an antenna then I doubt it was TVI. It COULD have been a problem with harmonics but more likely a problem of front end overload on the computer speakers. Another... sometimes having the computer off can cause more of a problem then when on. The servo outputs of the soundcard will fight interference via audio feedback. With the soundcard off, this is not happening. if the problem occurs when the computer is on it's best to see if the computer sound card ground is true earth ground, often times it is not. Check the shield of the input line in reference to the 3rd pin of the AC line of the monitor audio with an ohmmeter also. With no harmonics (proven with a spectrum anylizer) my son's and wife's computer speakers pick up RF audio, it's simple AM, all that's needed to decipher this is a PN junction of some sort. My pro soundcards wiht true earth grounds have NO problems and are closer to the radiator not to mention have CONSIDERABLY more power behind them and much more efficient speakers. Don't be fooled, we have this problem in broadcast all the time running clean and legal. Ferrites and grounding the shield helps almost every time. Chad |
Dale
Intermediate Member Username: Dale
Post Number: 369 Registered: 12-2002
| Posted on Tuesday, May 09, 2006 - 9:19 am: |
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if your running a power mic turn it allthe way down then turn it on just 1/8 of a turn modulation is one of many causes of tvi and power mic just amplyifly that.this may help if it doesnt help at all then id try grounds or if ya have grounds check them all dale/cef426 |
Georgeodjungle
Intermediate Member Username: Georgeodjungle
Post Number: 101 Registered: 1-2006
| Posted on Tuesday, May 09, 2006 - 8:37 pm: |
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also: have the swr changed? |
Kmt36264
Junior Member Username: Kmt36264
Post Number: 30 Registered: 1-2006
| Posted on Thursday, May 11, 2006 - 1:03 am: |
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The monitor cable probably already has one on it but the speaker cable most likely does not. Put one bead at each end of the speaker cable and loop the wire through it as many times as you can. |
Kmt36264
Junior Member Username: Kmt36264
Post Number: 31 Registered: 1-2006
| Posted on Thursday, May 11, 2006 - 1:00 am: |
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Try some ferrite beads or small torroids. I have bought several lots of them on internet auction sites very cheap. |
Vanillagorilla
Advanced Member Username: Vanillagorilla
Post Number: 558 Registered: 4-2005
| Posted on Thursday, May 11, 2006 - 7:34 pm: |
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Bronze... You asked if conditions can effect this. Well, my Grant is a KNOW killer on Ch5 TV. If I turn down the mic gain (or lollipop D104) I'll be "ok"...BUT if its raining out I can't even run a stock mic on it with radios gain up. YES...it's been clipped(the radio..not the ferret) by the previous owner and I have been meaning to put that on a switch . If its raining I have to go to the Pluto...doing 30w with another D104 but NOT clipped. I also opt sometimes just to go to a higher freq from .225 to at least .385 where I may not be as resonant on that TV channel...ssb also helps...where was I going with this? Oh yea...I may be overlooking something stupid but RAIN has an effect on my TVI issues even barefoot...BTW SWRs don't change much in my case...they stay under 1.6 from standard 1.2 I've been told by friends that they come through TV's or radios in the room that they have unplugged! HARMONIC overload and or excessive RF leakage! This of course with the heat on. I have never come over my own computer but have transmitted through a neighbors at times so I'm told...always with the clipped Grant not with the unclipped models...lesson learned. So...YES..in my case the conditions have an effect. For the record..the antenna system IS grounded but the equipment is NOT....yet Wanna talk about what that Grant will do to another neighbors OLD (telescopic antenna type) cordless phone on a rainy day!? They've since thrown it away. Hope I didn't run away with this too much. "Ferrets are animals..not RF sponges" ..I wouldn't cry if you wanted to try the "canary in a coal mine" experiment with a cat in the shack though. If Mr.Pickles won't wake up after losing all his hair its time to buy new coax. |
Gator44
Junior Member Username: Gator44
Post Number: 10 Registered: 1-2007
| Posted on Tuesday, January 23, 2007 - 12:32 pm: |
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I'm also having TVI issues!!Aaaarh..Can't seem to rid this monster.Comes over slightly on my big screen and real good over my b-room set. Is it possible its feeding back through my power outlets in my shop back into the house? All is grounded very well,swr's low (don't budge the needle at all)cable coax appears to be relatively new and all tv's are new. The only thing that's different now from the way i was running it is that i now have all plug in gear and before i was running my radio off a battery and charger???All new coax and jumpers on everything!!! HELP....! |
Gator44
Junior Member Username: Gator44
Post Number: 18 Registered: 1-2007
| Posted on Wednesday, January 24, 2007 - 1:18 pm: |
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Well not through outlets...re-grounded my 696 and the skipper and made a choke on the cable coax before it goes into the set and now no TVI problem...It was probably a bad ground on my radio i assume, but i'm back up and running and my wife does'nt keep calling me in my radio room saying i'm all over the tv.... |
Lonestarbandit
Member Username: Lonestarbandit
Post Number: 74 Registered: 10-2006
| Posted on Friday, March 23, 2007 - 8:24 pm: |
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well i have fb500 also and i go over my comp also.... and everywhere else also lol im supposedly doin 800 pep off that amp i say impossible and could be indicator of massive harmonics out of the fb500? |