Vectronics VEC-1402K - Manual (Page 16)

VEC-1402K Instruction Manual 2 Meter Pre-Amp Kit
14
signals. Many scanner listeners use 100 feet or more of poor-grade RG-58 or
TV-type coax between the scanner and antenna, not realizing this cable has
considerable loss. Police and radio amateurs may run only a few watts,
transmitting weak signals that may become lost to feedline attenuation before
ever reaching your scanner. By mounting the preamp at your antenna, you boost
weak signals before they enter the cable. This allows previously noisy or
unreadable signals to come in loud and clear at the far end of the line!
You can make a simple bias-T using a couple inexpensive molded chokes and
capacitors (see below), or you can buy one at most CATV supply houses. The
"T" keeps RF energy isolated from your power supply, and keeps DC voltage
from being fed into your receiver where it might do some damage.
Coaxial Cable
2.2 uH Molded Choke
Antenna
100 pF Capacitor
VEC-1402K
In Out
+
Bias-T
100 pF Capacitor
2.2 uH Molded Choke
+ 9 - 15 VDC -
To Receiver
Preamp
Warning: Never reverse-install a bias-T so DC voltage
is fed into your receiver's antenna
terminals. Also, never reverse-polarize the
supply voltage to your preamp (swap + and -
leads). In both instances, damage may
result!