Vectronics VEC-813 - Manual

VEC-813/814 Intermod Filter Owner's Manual
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Vectronics VEC-813/814 2-Meter FM Intermod Filter
GENERAL INFORMATION
The VEC-813 HT Filter and the VEC-814 Mobile Filter are especially designed to
eliminate squeaks, squawks, bleeps, and other strange noises caused by intermodulation
distortion. These "phantom signals" are caused by unwanted mixing between ham-band
signals and out-of-band traffic from pagers, public-service repeaters, aircraft, and other
powerful sources. Intermod signal are not only annoying, in many congested areas they
can render your sensitive wide-band radio useless!
The only cure for intermod is to get rid of the out-of-band signals that cause it. Your
Intermod Filter uses three high-Q bandpass sections plus two low-pass L-sections to form
a razor-sharp network. This knock-out combination passes signals falling within the two
meter band, while attenuating out-of-band interference. Attenuation of unwanted
commercial FM signals approaches -50 dB in most cases, and that's the difference
between extremely strong and completely gone! When the filter is engaged, intermod
vanishes. During transmit, RF sensing automatically switches the filter off-line.
The VEC-813 HT version comes with BNC connectors and is self-powered from a
internal 9-volt battery. The VEC-814 Mobile version uses standard SO-239 connectors
and runs on external 12-VDC. Both models uses state-of-the-art surface-mount
construction and special high-Q porcelain chip capacitors to ensure top performance.
Both are housed in a RF-tight case with an On/Off switch and power LED. The mobile
version uses a standard 2.1mm x 5.5 mm DC plug.
VEC-813 INSTALLATION
Before attempting to use the VEC-813 on your HT, you must install a 9-volt battery. To
do this, remove the two case screws, slip the battery into its spring holder, and install the
snap-clip lead connector. Use a premium-quality Alkaline-type battery for best results.
You may then plug the VEC-813 directly into your HT's BNC antenna connector.
Important: The filter's by-pass switching circuit draws power whenever the VEC-
813's power switch is turned on. For longest battery life, be sure to turn
the unit off when not in use--and whenever intermod conditions do not
require using the filter to copy stations. If your 9-volt battery should
run down while the unit is turned on, the VEC-813 will automatically
default to its "pass-through" mode, and no damage will result.
Important: A 50-mW or greater transmit signal is needed to activate the unit's
automatic by-pass switching. Do not exceed a transmitter RF output
power of 50 Watts, or damage may result. If using an external HT
amplifier, install the VEC-813 between the HT and amplifier.