Re: [A/S] TV Interference

[Rick Kunath <k9ao@xxxxxxxxxxx>]

>>Let me know what kind of lead-in wire or cable is on the set (coaxial 
>>cable or twin-lead) and how you have it connected to the set, antenna, etc.
> 
> We have a TracVision dome with coaxial cable connected to the TV.  The 
> external regular TV antenna is also connected into the same leadin.  

I am not sure how this may have been done by your TracVision Installer, 
but if indeed the external TV antenna and satellite TV output are in 
parallel, this is not proper installation practice. That said, I doubt 
if the connections are paralleled and most likely they are installed 
correctly. (I don't have a wiring diagram for the TracVision unit handy.)

> We have an A-B 
> switch to switch from our dish-antenna system to park cable.  We have tried 
> bypassing this switch and it doesn't make any difference. 

Good test. some of these coaxial switches are known to break the cable 
shielding integrity but as you already tested this, your model must be 
OK in this regard.

> Do you think it might 
> be the coaxial cable?

I doubt it, but there have been cases where poor quality cable has been 
used. More often it is improper installation of the cable connectors 
that is the culprit. If you had a professional installation, this is 
unlikely. Poorly installed connectors are sometimes easily spotted by 
visual inspection. They should not be a screw-on connector. The 
connectors should be crimped by a crimping tool, and have a full 
crimpable outer metal sleeve over the cable (solidly crimped by a 
crimping tool and not a pliers, the cable shell should have a 
symmetrical crimp), not a crimped small slide-on ring. You should be 
able to give the connector a tug and not have it pull off the cable.

But lets do the antenna-removed test and see what happens. Unscrew the 
coaxial cable from the back of the TV and let me know if you still see 
interference.

I want to know if the interference is getting into the TV via the 
antenna or the power cord.

If you have a small portable battery operated radio, you might use it as 
a sniffer on FM on an unused channel. Run the hair dryer or the lamp, 
something that will put the interference out continually. Move the radio 
around the trailer. See if there is any increase in noise as you get 
close to the power cord of the TV. Then go outside and place it at 
various places near the trailer's aluminum skin and see if the noise is 
strong there.

Let me know what you discover.

Rick Kunath
WBCCI #3060