TransWorld Antennas
TW8080
TM
12
TW8080
TM
Instruction Manual
Loading Array Operation. The loading array on the TW8080 consists of two
boxes (labeled “Side A” and “Side B”, below). The cover can be removed off of
each, and the coils inside tuned. Each half of the antenna (top half and bottom
half) is tuned by seven series-connected coils.
Equipment. The tuning process requires Voltage Standing Wave Ratio (VSWR)
measurement. These measurements can be accomplished using most any
antenna analyzer. However, these devices typically generate a very small signal
(less than 0.2W), and may show higher than expected VSWR readings. A
reading of 1.3:1 at the tuned frequency is typical at this low power. The VSWR
readings should decrease once the antenna is used with 5W of power or more.
The VSWR reading on your transceiver will likely show a lower VSWR than a
low-power antenna analyzer.
Cables. Make sure that the coax used for the tuning process is at least 65 feet
long, and that the coax is installed at a 45 degree angle as described on page
11.
Tuning. By spreading both “Top Coils” and “Bottom Coils” above, the tuned
frequency will increase. Likewise, compressing the coils will decrease the 80m
tuned frequency.
1) Preparation. To begin the tuning process, remove the loading array cover
using a small Phillips screwdriver and connect the coax cable to the loading array
box. The coax you use for the tuning process should ideally be the coax you
plan to use for the antenna during normal use. Connect the coax cable to the
device you wish to use to measure VSWR.
2) Tune. Determine to what frequency the antenna is best tuned. If you wish to
increase the tuned frequency, spread open all “Top Coils” and “Bottom Coils” on
the circuit board, as shown in the figure below.
