🚀 go-pugleaf

In article <1992Apr7.211551.942@pictel.com> wpns@pictel.com (Willie Smith) writes:
>In article <1992Apr2.183611.2614@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
>>In article <1992Mar30.151226.1035@eng.umd.edu> naiming@eng.umd.edu (Naiming Shen) writes:
>>>
>>>I want to install wires for cable TV and maybe used for baseband video
>>>signal also.
>>
>>RG59 is 75 ohm cable for baseband video and CATV RF uses.
>
>Umm, well, sort of.  CATV cable needs to have a full shield (foil is
>good) for leakage considerations, and the frequency response should be
>'good' from around 50 MHz to 500 MHz.  RG-6 is generally used.  RG-59
>is not reccomended due to lack of shielding.

RG-59 is a much abused label. At one time it was a military designator
with a mil-spec, but not anymore. There are lots of RG-59 *type* cables
available, some with belfoil shields, some without. Braid only shield
coverage of 95 percent is available as is cable with only 70% shielding.
Sticking to Belden cables is your best bet for quality cable.

>Baseband video needs to have a low DC resistance and a good frequency
>response from 15 KHz to (something like) 5-10 MHz.  RG-59 is generally
>used, though Belden 8281/9231 is reccomended for 'professional' use,
>like studio wiring.  RG-6 tends to have a relatively high DCR, and is
>not reccomended for use with baseband video.

Baseband is from 30 Hz to 6 Mhz and needs as flat a response as possible
with minimum group delay. We use equalizers on long runs of cable, but
try to choose a low loss cable because the equalizers always disturb
group delay characteristics. Time distortion of the video signal is
a much more serious problem than mere attenuation.

Our professional plants use Belden 8241, one of Belden's versions of RG-59,
for video wiring. We only use 8281 on runs that pass near sources 
of electrical noise. 8281 has double braid shielding, is larger and
much stiffer than RG59, and has more capacitance per foot so it requires
more cable equalization for long runs.

>To throw some more confusion into the discussion, BNC connectors for
>8281/9231 are difficult to come by, unless you want to spend big bucks
>for a crimp tool....  I'm going to have to wire our new house sometime
>Real Soon Now, but I'm not sure _what_ to do....

If you want to play with 8281, you've got to grit your teeth and pay
the $270 for the Kings crimp tool. We use Kings connectors exclusively
on all our coax at our plants. It is by far the most reliable connector
on the market.

Gary