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Page 23
When wiring the EHU’s on the DB42 Yagi, it is important to know that there are two different types of
EHU. The Driven element, Director 1 and Director 2 each have relays inside the EHU. The Reflector
and Director 3 EHU do not utilize a relay. Refer to the DB42 Yagi configuration guide in the
Preamble
section of this manual for more details.
The EHU’s that have relays, uses 6 conductor control cable; 4 wires to control the stepper motor, and
2 wires to control the relays. The EHU’s that do not have relays use 4 conductor control cable since
only the motor needs to be controlled for these elements. It is critical that the right control cable is
used for the respective EHU or the antenna will not function correctly, and the electronic controller
could be damaged.
This brings up an important note:
NEVER DO ANY WIRING WHEN THE ELECTRONIC CON-
TROLLER IS CONNECTED TO THE CONTROL CABLE.
Even if the power is turned off of the con-
troller, damage can occur. This is the number one cause of antenna installation failures, so please be
sure to heed the advice.
Figure 2.10
gives an overview of the inside of a SteppIR EHU.
Control cable tray
for routing cable
out of EHU
Relays (this space will
be empty if the EHU
has no relays)
6 position EHU terminal
header (4 position used
for EHU’s with no relay)
Element support
tube
Balun (the balun is only
inside EHU’s that are
driven elements)
Spring reel for
copper strip
SO239 connector
(for driven ele-
ment only)
Sprocket / platen
assembly
CHAPTER TWO
SECTION 2.1
MOUNTING THE EHU’S ON THE BOOM (continued)
ELEMENT HOUSING UNIT (EHU) WIRING OVERVIEW
FIG. 2.10
Serial # sticker