Specifications

APEX™ Exciter Incorporating FLO™ Technology
Navigating the LCD Display Screens Details of the System Setup Screens
Page: 3-40 888-2604-001 03/08/07
WARNING: Disconnect primary power prior to servicing.
3.6.3.1 Filter Type
The Setup > RTAC Setup > Filter Type applies the necessary amplitude response and
group delay precorrection, which reduces the distortions so that they are within the correc-
tion range of the RTAC circuits. Selecting the correct filter improves the correction and
speeds the initial automatic setup time. Choices are:
• Standard: This selection is used if the transmitter system includes the standard
D-Mask filter.
• Asymm STF: Use this if the transmitter system uses the sharp tuned filter (sometimes
called “Cool Fuel”) it also is used when the group delay for the transmitter is not sym-
metrical, such as when its output is reflected through an adjacent channel sharp tuned
filter in order to combine the two transmitters.
• FLO BANDPASS: Use this selection only if the system includes the FLO bandpass
high power filter.
• The Exciter must be restarted to make filter change active.
3.6.3.2 Max Peak Stretch
Peak stretch can cause nuisance overdrive trips in some transmitter models. When the
Apex adapts it’s non-linearity correction, the algorithm is designed to produce a peak
stretch up to a 3 dB limit. Nuisance overdrive trips can be avoided by programming the
maximum peak stretch parameter of the RTAC Setup Screen. The maximum peak stretch
is adjustable from 3 to 0 dB in 0.25 dB steps in order to limit the peak stretch that the Apex
exciter non-linear correction algorithm imparts to its RF output signal.
If they are going to happen, nuisance overdrive trips will typically occur within 30 minutes
to 1 hour after transmitter operation with RTAC is first started. If this happens, perform the
following:
1 Reduce the peak stretch from 3 dB to 2.5 dB.
2 Wait for one hour to see if further overdrive trips occur.
A If they do, reduce the peak stretch by another 0.5 dB.
3 Repeat step 2 until overdrive trips cease.
4 Excessive peak stretch reduction may effect the linearity correction of the transmitter.
A After peak stretch has been adjusted, observe the adjacent channel response
to ensure that they still exceed the transmitter output signal mask require-
ments.
3.6.3.3 RTAC Power On Mode
An RTAC Power On Mode parameter gives the customer the option of starting the exciter
in the bypass or default mode when AC power is applied.
• The default setting will load the RTAC correction settings which are held in the filter
set number displayed on this screen (the RTAC Setup screen) when the AC power is
applied to the exciter.
• In bypass mode RTAC settings are discarded and RTAC must re-adapt when the ex-
citer is switched on line.