Coax Terminators / Caps

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DPMin

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Pennsylvania
Hello,

I am wondering when and why coax terminators / caps should be used? For an example of the item I am refering to see: Ideal 85-038

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From what I've been able to find so far, it seems that when installed they prevent the signal from escaping, and thus improving the performance of the system. Is the improvement noticable? Should I use these on every jack I install?

Thanks!
 
It's not just signal ingress/egress. It is also signal reflections. When a signal gets to an unterminated point, it is reflected back from whence it came, where it is again reflected back down the line, where it again hits the unterminated end of line and is again reflected back, and so on. This can cause multiple images on any/all of the TVs/monitors on the same line. the greater the distance the signal travels in reflection, the worse the multiple image(s). It can also cause standing wave, which results in some of the information not making it to where it needs to go.

Same thing if a cable exceeds the minimum bend radius or is pinched by a nail or staple.
 
Never heard of them before but here is some info I found.

Global Spec The engineering search engine

?Coaxial terminators are electrical devices that connect to the ends of coaxial cables to prevent signals from reflecting back when they reach the end of the cable. They differ in terms of frequency range, power rating, voltage standing wave ratio (VSWR), return loss, and resistance. Voltage standing wave ratio (VSWR), a unitless ratio ranging from 1 to infinity, expresses the amount of reflected energy at the input of the device. A value of 1 indicates that all the energy passes through. Any other value indicates that a portion of the energy is reflected. Return loss is a measure of the match between the impedance of coaxial terminators and the impedance of the system. With coaxial terminators, choices for electrical resistance include 50 and 75 ohms.
Coaxial terminators use various types of RF connectors. Common types include BMA, BMMA, BNC, Type C, Type F, FME, Type G, MCX, MHV, and MMCX. Coaxial terminators with MMCX, Type N, QMA, QWS, SC, SMA, SMB, SMC, SSMA, SSMB, SMP, and TNC connectors are also available.?

JJ
 
Those are 75 ohm terminators. It is correct that they terminate the line to eliminate reflections. They also eliminate radiation and ingress which are big problems for CATV systems. No splitter port or jack should be left unterminated. You probably won't find cable companies using those. They will use something like it on the unused splitter ports and just not connect the runs to jacks not being used because they know that terminators will never be replaced once removed.

-Hal
 
75 ohm terminators

75 ohm terminators

I have been on several jobs where Verizon Fios was installed in customers home. In all homes the installer terminated every unused splitter port.
 
There are 3 reasons to use terminators.

1.) To prevent ingress from entering the system through an open port at the tap.
2.) To prevent signal reflections (which really isn't too big of a problem).
3.) To prevent cable theft.
 
MAK said:
What is a gilbert terminator? How does it differ from the ones shown in this thread?
Click to expand...
It is a special locking terminator that CATV companies use.

For example in my neighborhood the CATV company sets a pedestal, and each pedestal serves 4 homes, so each pedestal has 4 taps. It is very easy to get into the pedestal. All one would have to do to connect themselves is simply plug their feeder cable in on of the taps. The CATV company uses a Gilbert Terminator to prevent you from doing that.
 
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