The document summarizes an 860 DSPi 85 MHz return transmitter board. It allows the technician to use an 85 MHz low pass filter and turn on a pre-amp for added 17 dB amplification of signals below 85 MHz. Key benefits are seeing deeper into noise levels, preventing meter overloading, and aiding in noise tracking. The board can be verified by checking for "Transmitter (85mhz)" under the unit's Calibration Info screen. The pre-amp/LPF can be turned on/off from the unit's Spectrum mode menu.

1. Application Note
860 DSPi 85 MHz Return Transmitter Board
The 860 DSPi with the 85 MHz return board P/N 2072133000 allows the technician to utilize and 85 MHz
low pass filter (when activated), it also allows the technician to turn on the Pre-Amp which is now
activated with this board. The Pre-Amp / Low pass filter can be turned off and on inside the Spectrum
Analyzer mode. The Pre-Amplifier adds in +17 dB of amplification. The low pass filter runs from 85 MHz
and below, cutting off anything above 85 MHz.
There are three distinct benefits to having the Preamp/LPF built inside the 860 DSPi:
1. Allowing the technician to dive deeper into the noise, where as before he could not see down that
low.
2. Keeping the meter from overloading due to forward channel power.
3. This feature makes a considerable difference when tracking noise in the system.
The screen capture shown to the right provides
an example of the information shown on the
Calibration Info screen, this information can be
used to verify whether this option has been
installed in the 860 DSPi.
To determine if the 860 DSPi has the 85 MHz
return transmitter board installed, turn on the
860 DSPi, press the "Setup" softkey, then go
into "Info". Under Calibration Info you should
see Transmitter (85mhz).
The screen capture shown to the right provides
an example of how to turn on/off the
Preamp/LPF.
To turn on the Pre-Amp go into the "Spectrum"
option on the installer screen. Once inside,
press the "FN" key on the 860 DSPi. This will
open the function menu and then select the
option "Preamp / LPF". Once the Preamp/LPF is
turned on you will see in the upper right on the
spectrum graph "Preamp/LPF", this indicates
you are using the Preamp and Low pass filter.
Note that the Preamp/LPF mode uses the
alternate input connection.
For Additional Help Contact
Trilithic Applications Engineering 860 DSPi 85 MHz Return Transmitter Board
1-800-344-2412 or 317-895-3600 P/N 0010275077 – Rev 6/11
support@trilithic.com or 1 of 1
www.trilithic.com
Copyright © 2011 Trilithic, Inc. All Rights Reserved.