Re: Best brand coax and F connector for HD cable?

[Ed Nielsen <egnlsn@xxxxxxxxxxx>]

 From a leading engineer in the CATV industry:  "We did a scientific
research for a year on CPD and contact interfaces, the report shows us
that it is very important to break through the oxide layer to prevent a
non-linear behavior in contact surfaces. The torque varies with the type
of plating used on the F-connectors.

Finger tight is not tight enough to break through the oxide layer, and
due to temperature cycles it will loosen up after a while.  Especially
in the neighborhood of the subscribers and RF output of the node it is
important, (the effect of a loose or bad connection is the biggest at
those points) to have proper contact interfaces.

CPD ? This phenomenon, also known as Common Mode Distortion, is
generally the result of age and corrosion in the cable plant connectors.
  This non-linear function is commonly caused by oxidation of metal
surfaces, creating a point contact diode.  Should the diode effect occur
on the ground portion of a connector, common mode distortion and ingress
are likely.  The effect that this diode phenomenon causes is observed as
difference products in the return plant, and can be caused by one or
more faulty connectors.

In general, interfering products will be observed at harmonic intervals
of 6MHz throughout the return plant band.  Sidebands of this will tend
to raise the apparent noise floor.  Because common mode distortion is a
non-linear effect, slight variations in the point diode structure due to
temperature, humidity, wind velocity, etc. have a significant impact on
the interfering levels observed."

Manufacturers and the engineering community in the CATV industry
recommend they be tightened to 30-in/lbs.  The best that can be achieved
by hand is less than 13.


CIAO!

Ed N.

Robert L Bass wrote:
>> ...connector wrench (screwdriver handle with
>> an open hex wrench on the end) won't fit on
>> them - the SNS connectors are too big so I
>> end up tightening them by hand...
>
> That is actually a good thing.  There is no reason to tighten the fittings more than "finger tight."  The electrical connection is
> not made any more or less gas-tight.  Tightening them with a wrench only stresses the connection between the cabinet and the
> fitting -- definitely not a good thing.
>