Revised 14 June 2003
1
USER MANUAL / ASSEMBLY INSTRUCTIONS
CAL-AV Labs, Inc. 2D-40A
DUAL-DRIVEN ELEMENT 40 METER ANTENNA
DESCRIPTION:
The 2D-40A is a rotatable horizontal array of two full-size, closely spaced driven
elements. Each element is about 70 feet long. The rear element is longer than the front.
They are fed approximately 140 degrees out of phase, using a shielded phasing line that
is inside the boom. The pattern is cardioid, with a free space forward gain of 6.5 dBi
and a front-to-rear ratio of 20dB.
Matching and fine tuning is by means of hairpin transmission lines mounted along the
underside of the boom near the feed point of each element. Both hairpins are adjustable.
The front hairpin is used to set minimum VSWR, which is specified as adjustable to 1.0:1
anywhere in the entire band. Adjustable element tip lengths set the intended operating
frequency of the array. It is noteworthy that all four element tips are moved by the same
amount for a frequency adjustment. The rear hairpin adjusts resonant frequency over a
small range, approximately 70 kHz.
Feed connection is by means of an SO-239 UHF receptacle located in the RF neutral
section of the forward hairpin. This patented feed, phasing, and matching system also
functions as a wide band, high power balun. Also, because the elements are electrically
connected to the boom at the neutral points of the hairpin sections, both a static drain
and a dc path for lightning-induced EMP or direct-strike current are provided.
In no-ice conditions, wind survival is 100 mph. With 1/2 inch of ice loading on the
elements, the wind survival is de-rated to 40 mph. Weight of the 2D-40A, including
hardware, mounting, and matching accessories, is 163 pounds (74.1 kg). For more
detailed information, including specifications, drawings, parts list, patterns and graphs,
please see the appendices.
UNPACKING:
The 2D-40A is shipped in three cartons; two are about 7 feet long, and the third is about
a 2-foot square.
Inspect cartons for any sign of shipping damage. Then open cartons and inspect the
contents for hidden damage. Shipping damage is not a common occurrence, but it does
happen. If damage is found, save the cartons and packing materials, and notify the
carrier.
Remove contents and inventory for the following:
Carton 1:
1 of each of the following: Front, rear, boom and mast mounting plates
1 kit Mounting plate hardware.
