Can I expand the PA821 by linking a PA760 or PA770?
It is possible to use a PA760 or PA770 with the PA821:
On the front panel of the PA821 is a bnc jack labeled "MAIN OUT." To the right of this is a group of 3 bnc jacks labeled "EXPANSION PORT."
Connect a short bnc-to-bnc cable (included with the PA821) from the "MAIN OUT" bnc jack to the "A IN" bnc jack of the expansion port.
Use an additional bnc-to-bnc cable to connect from the "ANTENNA OUT" bnc jack on the rear of the PA760 (or PA770) to the "B IN" bnc jack of the expansion port.
Finally, connect an antenna (or cable and antenna) to the "A + B OUT" bnc jack. This is now the combined output of the PA821 and the PA760.
The section labeled "EXPANSION PORT" is actually a high-quality passive 2-into-1 combiner. Since it is passive it does introduce a loss of about 3.5dB in the combined output signal. However, this should not significantly reduce the overall capability of the systems.