• Cable 2 [ 2] (55.55 Mhz) = 6 Meters
• Cable 17 [ D] (139.25 Mhz) = 2 Meters
• Cable 18 [ E] (145.25 Mhz) = 2 Meters
• Cable 23 [ J] (217.25 Mhz) = 1.25 Meters
• Cable 24 [ K] (223.25 Mhz) = 1.25 Meters
• Cable 64 [UU] (421.25 Mhz) = 70 Centimeters
• Cable 65 [VV] (427.25 Mhz) = 70 Centimeters
• Cable 66 [WW] (433.25 Mhz) = 70 Centimeters
• Cable 67 [XX] (439.25 Mhz) = 70 Centimeters
• Cable 68 [YY] (445.25 Mhz) = 70 Centimeters
• Cable 69 [ZZ] (451.25 Mhz) = 70 Centimeters

 This interference can go both ways! In the majority of the cases reported, the interference was caused to the cable by the amateur. But there have been instances where there have been large enough leaks from the cable system to interfere with the amateur! From what I have seen, these instances have been created by either an improperly terminated cable ends (unconnected!), or by customer-installed "illegal" hookups. Rarely, the problem can be caused by a bad cable distribution amplifier or shield break somewhere on the pole cable.

 As an example, I was receiving a S9 carrier on 145.250 on my packet radio. My radio was an Icom 28H and I had an 11 element vertical beam at 60 feet. I reported this to my cable company. A few days later they sent out their Engineer and DF Vehicle. I brought him up in my shack and showed him the interference. We used my beam antenna to determine that the interference was coming from a beam heading of 315 degrees (NW). We went to our vehicles and found on that heading, the offending equipment 500 yards away! It was an improperly terminated connector inside someone's house! An illegal hook up! So you can imagine what a bad distribution amplifier outside your window will do! Most of these leaks can be easily located with your HT or a hand held scanner. These are a few frequencies to listen for:
 
 
 

• Cable Channel 17 (D) --- Audio at 143.75 Mhz.
• Cable Channel 18 (E) --- Video at 145.25 Mhz.
• Cable Channel 18 (E) --- Audio at 149.75 Mhz.
• Cable Channel 23 (J) --- Audio at 221.75 Mhz.
• Cable Channel 23 (J) --- Video at 223.25 Mhz.

If leakage from the cable system caused harmful interference, it is the responsibility of the cable operator to eliminate the interference, regardless of the cause. If they determine that the leakage is coming from a subscriber's home, they must, if necessary, disconnect that home until the cause of the interference is found and corrected.

Part 76 of The Federal Communications Commission Rules and Regulations, which governs the Cable Industry, clearly states:

 76.613 Interference from a cable television system. (a) Harmful interference is any emission, radiation or induction which endangers the functioning of a radionavigation service or of other safety services or seriously degrades,obstructs or repeatedly interrupts a radio communication service operating in accordance with this chapter. (b) The operator of a cable television system that causes harmful interference shall promptly take appropriate measures to eliminate the harmful interference.

 There is much more to be read out of this part of the FCC Rules and Regulations and can be seen at yourlocal Field Operations Bureau if you are interested.

In these bulletins, I am going to focusmostly on the type of interference caused to the Cable Channel 18, 24, and 64-68. The reason for this is two-fold. One, is because these are the channels that most commonly experience fundamental overload interference from amateur stations, and, two, because any interference caused by amateur stations to these cable television channels is clearly not the legal responsibility of the amateur. Depending on the ultimate cause of the problem, it may be the responsibility of the cable operator, the TV manufacturer or the subscriber.

 (Continued in Part 3)