3-8. TEST ADAPTER. Continued
All resistors used by the power supply, except for R3, are mounted on the test adapter power supply CCA
e. RF Signal Routing. This section routes RF signals to and from the reference radio and UUT antenna
connectors and the test equipment.
Relays K1, K2, and K3 control the flow of the RF signals. Each is controlled by the RF switch (S3). 27.5 V dc is
supplied to the positive control lead (+) of each relay. Each relays negative control lead (-) may be connected
to GND through the RF switch. When the negative control lead is grounded, current flows through the relay coil,
shifting the relay output from the NC output to the NO output.
Attenuators AT1 and AT2 decrease the signal strength of RF signals input from either the reference or UUT RTs.
This prevents damage to an RT from a high power input signal. AT3 provides a 50-ohm matching impedance to
the RF DET output.
f. Switching. The switching section is composed of a variety of switches which perform signal routing
Table 3-1 describes them and their uses. The switches are shown in detail in the schematic of figure
Figure 3-3. Test Adapter Interaction Block Diagram