Category Archives: Cabling

Mismatched connectors and cable causing bad reception – How long things take to change!

Did you know that every type of cable spec is designed to work perfectly in conjunction with its matching connector?

So many times do we at Deeper Image find poorly fitted F connectors causing bad reception.  General electrical contractors are a common perpetrator of this, but specialist antenna installers also are guilty of not using the appropriate F connector for a given specified cable.

Deeper Image records show that the most common reception fault from a repair service point of view is mismatched or wrongly installed connectors and cable.  Out of every 10 service calls that we make, 7 of them are for cable and/or connector problems.

A common fault is for the shield to be pushed back under the PVC outer jacket: Wrong! This totally defeats the purpose of the shield.

A well-fitting F connector goes on easily and the shield remains flat against the dielectric.  When badly fitted it allows impulse noise interference, there is nothing to stop this happening. There are plenty of interference sources: electrical motors, refrigerators, 12-volt down lights (a bad one) and electric fences, to name a few.

The F connector entered use in Australia in the late 1960s or early 1970s.  An American company called Channel Master manufactured or sold the first drop taps — splitters which were fitted with the early F connectors.

Some consider that it was the Foxtel cable company that really started pushing this type of connector; however Deeper Image’s founder Sally Garden had earlier installed the first MATV Systems in the 1970s using them. We were certainly the pioneers. We therefore consider ourselves experts in the selection of the right connector for the right cable.

One of our spec sheets for signal processors, around 1980, clearly shows the F connectors as part of the installed equipment.  When you consider the antenna industry generally still used saddle and screw equipment up until the year 2000 it is apparent that it has taken a long time for the right type of connector to be used, and unfortunately even today you will find saddle and screw devices being sold and used.

Sally Garden estimates it took about 30 years for F connectors to come into general use, although commercial equipment adopted the F connector earlier.

Pixelation and Cable

In analogue days the blight of a poor television picture was the ghost. You could put up with it to a certain extent but it became unacceptable once it got bad enough to confuse the image like in sporting events. Another problem was the weak or snowing type picture. That has all been replaced with the digital version “the pixelation of the screen” as it becomes unstable or when really bad the message on the screen reads: “no signal”.
Today 70% of digital faults inspected by the digital antenna technician are cable and connections problems. REALLY good cables did not become common until well in the 90′s. There were professional organisation that started to use high quality cables as early as 1986 but that was rare. Most TV cables being sold were solid copper centre conductors with copper shields – these cables are still in use today. Slowly but surely the foil cables started to be used but were only available in a RG59 size. Both types of cables are the cables which are causing the problems today. Over the years being subject to heat and cold they have fractured and though unseen to the eye never the less they will no longer perform well and predictably. They are also deteriorating with age. They are particularly vulnerable in hot weather as the centre core expands. Evidence suggests that if put under a microscope we would see very small fractures.
I first imported the foil cables in the 80’s as I recognised the superior performance of these cables much earlier than the general industry. As a consequence many of the installations I had something to do with still operate successfully today. TV signal cannot be seen so problems are often solved by observation and patterns and then worked backwards to solve the TV problems noted! This is a skill combined with interest – mine has never waned!
Good technicians have known for years that nicks or poorly handled cables produce random and unpredictable results. If a cable stretches there is a reduction in the conductivity of the cable. The electrons have barriers to get around and can no longer flow effortlessly. This increases the errors in the packets. So if you have a problem where it is good sometimes and bad another and no one can find out why then it is most likely you need your cable changed. The technician comes puts his meter on it and says “no problems here” That is a true statement but there is a problem and he/she should investigate what cable is installed, how long it has been there and if there are individual household environmental contributors that are contributing to the data loss. This is what is so much harder with digital antenna installations you have to rely on your meter only, as visual observation is next to impossible when you have tricky situation to solve. It is experience and a willingness to answer the question “WHY”.
Pixelation – the statistics are 70% of faults are cable and or connections
                                         
Pictures how correctly crimped F connectors which are ideal for digital television reception. Today the F connector is the industry standard and reduces random pixelation. They are an important part of a digital television antenna installation. The one of the right is a good quality twist on which the home handyman can install.
Next – Some interesting phenomena reported by customers and observed by technicians