Re: Poor antenna reception on channel 13

John, I do some work on TV antennas for commercial installations in 
hotels.  Most of the problems I find with reception are related to 
corroded connections between the coax and the antenna.  Usually I crimp 
a new connector on the coax, or replace old weathered coax and 
everything starts looking good again.  Since your problem happened 
suddenly after a few days, it may not be corrosion related.  I would 
check the connection between the coax and the tv antenna.  You probably 
have a device called a balun connecting the coax to the antenna.  It 
converts the coax cable to a twin lead type of connection which usually 
attaches to the antenna with wing nuts. Make sure both of those leads 
are still attached to the antenna.  If the balun looks corroded or 
weathered, replace it with a new one, they are inexpensive.  Look inside 
the coax connector outside, the copper should be shiny and copper 
colored, not rusty or dark.  If it is replace the coax.   Also check 
inside for loose or bad connections at the tv.  Very often I find bad 
cables connecting tv's to the wall plate.

As far as a meter for off air reception, there are field strength meters 
used in the cable industry, but they are expensive (>$1000) and you can 
get by fine without one.  I would buy/borrow a pair of family walkie 
talkies and have one person check the tv channels while you work on the 
antenna.

Good luck,
Chris

John wrote:
> I have a Radio Shack antenna (model VU-190XR) and I live in Southern
> California (Orange County).  I mounted the antenna to my chimney a
> year ago.  At the time I mounted it, I had reception problems on
> channels 2 and 4.  I tried everything to fix it and I was not able to,
> so I paid an antenna professional to come out and adjust it.  When he
> adjusted it every channel looked great.  Everything was fine for the
> past year, until three days ago.  I am now having problems with is
> channel 13, which is so out of tune I cannot watch it.  The picture
> and sound is absolutely terrible.   The reception on channel 13 looks
> like it is not tuned in properly.  It reminds me of a T.V. with rabbit
> ears that need to be adjusted.  I checked the antenna for physical
> damage and everything looks fine.  All the elements are extended out
> properly and nothing appears to have changed.  I don't think the issue
> with channel 13 is interference, because the characteristics of the
> picture do not look like interference.  
>  
> When I paid the antenna professional to come out last year to adjust
> channels 2 and 4, he told me he "fine tuned" the antenna.  I remember
> him telling me he had some kind of reception meter he attached to the
> antenna to make the adjustment.  Do you have any suggestions how I can
> make the adjustment myself to get channel 13 to come in clear again?
> Also, about the reception meter, I checked Radio Shack online to see
> if they have something like that and I did not find anything.  Do you
> know where I could buy some kind of reception meter?  I appreciate any
> suggestions.