[RFI] Eliminating TVI

N6KJ kelly at thejohnsons.ws
Fri Dec 26 13:36:12 EST 2003


Thanks for the advice, but that test proved to be inconclusive.  The
problem is that the primary symptom of the interference is that a color
signal becomes somewhat black-and-white.  I can see little horizontal
color lines, but for the most part the interference only affects the color.
With no input all there is is black-and-white snow.  When I transmit with
no input I see no interference.  What I really need is some way of supplying
an input that is practically guaranteed to be interference free...something
like a piece of test equipment that supplies a picture through a very
short, well shielded cable, preferably running off DC.

Someone suggested a few days ago that I try displaying one of the tv's
menues instead of an input signal and see if the interference is there.
Well, it isn't.  I see no interference when the menu is on the display.
Of course, I don't know what this tells me.  I'm sure this rules *something*
out, but I'm not sure at what point in the RF/IF/etc chain the menu gets
injected.  

On Tue, 23 Dec 2003 20:49:24 -0500, "Tom Rauch" wrote:

> 
> If it were my TV, I'd disconnect all the interconnecting cables except the
> power cord. I would add a good differential and common mode filter on the
> power cord.
> 
> I'd watch the snow on an unused channel, and see if it changes when the TX
> is operated.
> 
> If it does, I'd look for another TV. If not, I'd add external connections
> one at a time until the TV messes up.
> 
> 73 Tom
> 
> 
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