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amateur radio 101

Cables & Cords

Here we will begin a discussion on cables and cords. What I mean by this is all the stuff that connects the antenna to the transceiver, and what connects the transceiver to the power source. If you're looking for a Excellent book on wire try this one. Lets begin shall we?

Coax-Coaxial cable

This is the most widely used and versatile cable that you will probably come in contact with. This is the same cable that you see with your cable TV. It is typically used in feed line applications for our purposes, i.e. it is a cable that is used to go between the antenna and the radio. It consists of a center conductor typically made out of copper or aluminum coated with copper; this center conductor can either be a solid piece of wire or stranded. Next comes the Dielectric which insulates/separates the flow of electrons of the center conductor from the flow of electrons in the next part the outer shield. The outer shield is typically grounded out creating a kind of cage around the center conductor to keep it from getting any spurious interference from outside. Please also be aware that some cables come with a foil shielding between the dielectric and the outer shield, this is to assist with further insulating the center conductor from spurious signals. In some cables this can be a 2nd braid or on larger cables this can even be metal tubing. The insulating jacket or outer layer is made from a number of different materials depending on the application but typically it is made from a polyvinyl chloride plastic.

Coax Connectors

The two most common connectors that you will see on coax cable are "UHF" connectors, which you will find on most of your cables in amateur radio for mobile and base station applications, and "F" connectors like on your cable TV shown respectively below. There are a couple of others "N" connectors, "SMA" connectors, and "BNC" Connectors that i may add in later.

Ladder line-Twin-Lead || Balanced feed line

This is another type of cable that is also typically used in feed line applications. This cable is two wires typically 20 or 22 awg(gauge), They are held at a precise distance apart by the polyethylene jacket that typically covers the twin feed lines. The parallel transmission lines allows for lower signal loss than coaxial cable. any changes in the spacing would cause the RF signal to reflect back down the line to the source. There are two common types used in amateur radio; 300 ohm twin-lead with has a spacing of about .5 inches and 450 with a spacing of about 1 inch. Note: the gauge of the wire used in the twin-lead will affect the distance between the leads to maintain the 300 or 450 ohm impedance. Also note that for most applications this line will be attached to wing nuts on the back of the radio or tuner, and typically go into a Balun or just soldered into the antenna.

Power cord-zip cable || red & black cable

This is the stuff that typically comes on mobile rigs and is what you buy if there is not enough to reach the battery, or to make jumpers for changing connectors or adding fuses. 12 awg is what comes on most radios that use zip cord. 10 awg will suffice for most applications, it has the load capacity to carry current for almost all the manufactured radios. Using smaller than 12 awg is really not recommended as your current draw may be more than the wire can handle. and using 8 awg should be reserved for long runs(still looking that up) and for when using multiple radios or adding an amp. Although typically I like to run seperate cableing from my power source to each piece of equipment (note: I also like to have fuses in both sides as well for each).

Additional information

.... can be found in the following books