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Side Length in
Feet
Diagonal
Physical Length
in Feet
Factored 0.95
Electrical Length
in Feet
DLY3 Physical Length
in Feet (0.85 VF)
135 (160m)
190.9
181.4
154.2
98 (160m & 80m)
138.6
131.7
111.9
70 (80m)
99.0
94.0
79.9
Table 3 - Examples of DLY3 Required Length
After calculating the required electrical length, you must include the VF of the coax being used
when determining the correct physical length of DLY3. Multiply the factored electrical length by
the VF. The result is the correct physical length for DLY3. See
Figure 4
and the sidebar for an
example.
Note:
These calculations are in feet, not feet and inches.
To find the physical length of DLY3, calculate the
diagonal length of the array by either directly
measuring the diagonal or by multiplying the array side
length by 1.4142. DLY3 will be significantly shorter
than the actual physical length. The diagonal length is
first multiplied by 0.95. This gives the factored
electrical length for DLY3. Next, multiply the DLY3
electrical length by the VF of the delay line coax. The
result is the correct physical length for DLY3.
Figure 4 - Diagonal Dimension
For Example
: An array with 90 foot side spacing, the diagonal length is 127.3 feet. The 0.95
factored physical length for DLY3 electrical length is 120.9 ft. Multiply 120.9 ft.
by 0.85 (the VF of DX Engineering 75
Ω
coax).
The correct physical length for DLY3 is 102.77 feet, or 102 feet 9 inches.
Delay lines DLY1 and DLY2 must be half the length of DLY3. Make DLY1 and DLY2 as close to
half the physical length of DLY3 as possible. To avoid performance degradation due to inconsistent
coax construction, all the delay line coax should be cut from the same spool.
Delay line cables can be neatly coiled in a 1-1/2 ft diameter coil. Support the weight of the cables
by taping or securing them to the support pole or mast rather than allowing them to hang from the
connectors.