I am grateful to ND0B, who provided information on how the circuit board of the this ARR preamp was laid out, making it very easy to break into the preamp output line, and provide the option of breaking out the preamp output to route it to an external receiver.  In my case, I wanted the option of connecting the preamp to a USB RTL Dongle on my laptop computer when operating portable. 

As can be seen in the photo below, the standard ARR preamplifier was simply mounted in a new die cast aluminum enclosure, adding a power recepticle for the 12 VDC input, along with an RCA connector for manually putting the preamp into transmit (bypass) mode.  The photo was taken before I installed an LED pilot lamp next to the 12 VDC connector, to indicate that the unit had power.  

The photo below illustrates where the circuit board trace was broken.  Each side of the circuit was connected to newly added BNC connectors.using silver plated straps.   A short BNC jumper connected to those terminals restores the original unit operation of providing preamplifier output to the transceiver.   However, the preamp output can also be connected to a low loss splitter so the transceiver and a separate receiver can share the preamp, or the preamp output simply just can be routed directly to the separate receiver.

(August 8, 2017)