Create your free account now! Sign up

Re: Adding channels in the FM band

To add to what Joe said. An ingress (high pass) filter only cuts out 5-45 MHz, the FM band goes through just fine. Fix leaks, tighten every connection and make sure all drop connectors are up to spec. Try to get the head end to move any highly watched channels away from the FM band. 

  To make a near field probe to find QAM leaks:

Use a 26" piece of coax, cut a connector on one end

about 6" from the connector, cut out 1/2" of the jacket leaving the braid intact

at the other end strip back the dielectric and shielding to expose 2" of center conductor

bend the cable in a circle and wrap the center conductor around the exposed shielding leaving 1/4" space between the shielding and the dielectric

wrap the exposed dielectric and shielding with black tape making sure the center conductor is the only part touching the shielding, the loop should be about 6" in diameter

To use, set meter to spectrum analyzer

Turn off the low pass filter

Turn on the pre amp and set the freq. you want to look for.

When you find a leak you will see the familiar haystacks of a QAM carrier.


Don't forget to turn the low pass filter back on before looking for upstream ingress.

I have used this to find a crack in jacketed cable that wasn't leaking in the mid band.
Never argue with an idiot, they will drag you down to their level and beat you with experience. Winston Churchill
This is CABL.com posting #362924. Tiny Link: cabl.co/mbGzM
Posted in reply to: Adding channels in the FM band by ddickens
There are 0 replies to this message