Campbell Scientific RF401-series and RF430-series Spread Spectrum Data Radios/Modems - Manual (Page 24)

RF401-series and RF430-series Spread Spectrum Radio/Modems
3.3 Antenna Considerations
3.3.1 Line of Sight
The single most important factor in radio performance is antenna placement.
As Appendix H, Distance vs. Antenna Gain, Terrain, and Other Factors,
states, “height is everything.” The two radios must be able to ‘see’ each other if
distances over a mile or two are required. This can be accomplished with a
mast or tower.
3.3.2 Mounting
The higher the gain of a yagi antenna, the more important it is to aim the yagi
precisely and mount the yagi solidly to prevent movement due to strong winds,
large birds, etc.
3.3.3 Antenna Cable Routing
The antenna cable should be routed in a protected area and made secure against
damage from wildlife, wind, and vandalism.
3.3.4 Antenna Cable Weather Sealing
The presence of water inside the antenna cable’s plastic sheath can attenuate
your transmitted and received signals significantly. The RF energy, instead of
traveling the length of the cable with little loss, is absorbed according to the
amount of water present (like in a microwave oven). A small amount of water
can ruin a once good communication link.
When moisture gets inside the sheath it is very difficult to remove. Some
careful cable handling (even pinholes can let in significant amounts of water),
thoughtful cable routing, and good weather-proofing can prevent this.
Apply a 1/8 inch thick coat of pure silicone rubber compound (RTV) 1) where
the cable connector screws onto the antenna connector (apply after the
connector is in place allowing future removal) and 2) at the junction between
plastic cable sheath and cable connector. If carefully done this should last for
years. An alternative approach is to wrap self-vulcanizing rubber tape around
these same areas of the antenna connector, cable connector and cable sheath.
This tape can be purchased at most electrical supply stores (see Section 6,
Troubleshooting, item 6).
4. System Components
4.1 RF401 or RF430 Radios
4.1.1 Indicator LEDs
The radios have a red LED labeled “Pwr/TX” and a green LED labeled “RX.”
When 12V power is applied the red LED lights for ten seconds. About 3
seconds after power-up the green LED lights for a second. Ten seconds after
power-up the selected standby mode begins to control the red LED. The red
LED lights to indicate when the receiver is actively listening. When the
receiver detects RF traffic (header or data with the same hopping sequence),
the red LED will light steadily. When the RF401 is transmitting, the red LED
will pulse OFF as the RF packets are transmitted (it will not be on solid).
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