Lit Number: 11-06-21-068
Page (14)
4.3.1.2 Litze
Wire
Because a low resistance is required for high Q antennas, Texas Instruments use
Litze Wire in their antennas. Litze wire uses multiple (e.g. 120) individually insulated
(lacquered) wire stands, covered in silk to make up the wire. As each strand is twice
the skin depth, total current flow occurs in each strand and for a particular wire size,
eddy currents are eliminated. Result – low impedance wire and, because there is only
a thin silk outer layer, multiple windings are kept as close together as possible.
Figure 15. Litze Wire (3 sizes)
Litze wire has its disadvantages though:
•
It is expensive
•
It is more brittle and liable to break if vibration is present.
•
It is more difficult to work
One re-occurring issue is when a standard antenna connector breaks off. The
temptation is to strip off the silk and crimp a new connector onto the copper wire.
Unfortunately, you are crimping onto the insulating lacquer, and the antenna will no
longer work effectively. When using Litze wire, the insulating lacquer has to be burnt
off in a solder pot.
Tip 1:
If just the wire is put into the solder pot, solder flows up the wire by
capillary action and the wire swells at the end and is too large for the
connector. Always lightly crimp the terminating connectors onto the wire
before putting into the pot.
Tip 2:
Commercially available solder pots are rated at 320 ºC (608 ºF) but
struggle to reach that temperature. Some have space for an additional
heating element. Buy a spare set and add the extra element.
Summary of Contents for 2000 LF Series
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