Practical_Antenna_Handbook_0071639586

632 p a r t V I I I : M e c h a n i c a l C o n s t r u c t i o n a n d I n s t a l l a t i o n T e c h n i q u e s
Figure 28.5 Center insulator connections.
Note Use only resin-Âcore solder for antennas! Typical solder is 50/50 or 60/40 lead/tin ratio
and may be labeled “radio-ÂTV” or “electronic” or something similar. Newer solder alloys,
without any lead, are also available. Most plumber’s solder is acid-Âcore and will destroy your
connection within a short time.
The life of the solder joint can be extended by painting it with nail polish or spraying
it with an acrylic lacquer such as Krylon, after the joint has cooled. As with the soldering
process itself, the entire assembly should be not be moved or jostled until the
coating has dried.
Keep in mind that even “new” copper wire needs to be sanded or scraped. Bare
copper wire may, in fact, have a clear enamel insulation on it that isn’t obvious to the
eye. But all bare copper oxidizes, forming an insulating layer over the conductor; the
early stages of that process result in only a slight dulling of the surface, so cleaning off
the wire immediately prior to soldering it is an excellent habit to form. Similarly, when
preparing the center connector, it is also good practice to use steel wool or sandpaper
on the solder lugs to remove any oxidation that may have formed over time. Oxidized
metal simply cannot be soldered!
An SO-Â239 UHF coaxial receptacle (socket) on the bottom of the center support device
shown in Fig. 28.5 accepts any feedline terminated in a standard PL-Â259 plug. Once