Tait International Limited TBCK4B Manual Do Utilizador

TB9400 Installation and Operation Manual

© Tait Electronics Limited September 2011

Do not remove the load from the PA while it is transmitting 
as this may damage the PA output stage.

The RF input to the 

base station

 is via the marked BNC connector on the 

rear panel of the reciter. The RF output is via the N-type connector on the 
rear panel of the PA (refer to 

Cables and antennas should be of high quality construction. Solid shield 
heliax type cables are best, but if braided shield cables must be used for short 
distances, their braids must be silver-plated.

We recommend the following installation procedures, which should protect 
the PA from damage under all but the most extreme operating conditions.

1.

Do not connect the PA directly to the antenna. Fit an isolator or 
duplexer between the PA and the load. Fit the isolator as close as pos-
sible to the RF output connector on the PA. Do not connect any 
switching equipment between the isolator and the PA, unless the 
switch cannot operate while there is RF present (i.e. the 

base station

 

is transmitting).

2.

Fit a surge suppressor to the antenna cabling where it enters the 
building.

3.

Inspect all cables and equipment connected to the 

base station

 for 

defects.

Ice on the antenna, or a broken antenna, is unlikely to cause damage to the 
PA. 

The circuit design of the PA protects the circuitry from high VSWR. This 
makes it difficult to damage the RF power device by keying the PA into a 
mismatched load, or if the load deteriorates over even a short period of time 
(milliseconds).

However, it is possible to damage the device if all the following conditions 
happen at the same time:

■

there is a step change in the PA load (for example, the load is removed)

■

the PA is transmitting

■

the feed line loss between the PA and the mismatch is < 1 dB.

The effect of such conditions is variable: some devices will not be destroyed, 
and some may fail after repeated load interruptions.