E8257D/67D, E8663D PSG Signal Generators Service Guide 315
Assembly Replacement
A24 20 GHz Highband Coupler (Options 503, 509, 513, 520, and 521)
Figure 3-32 A24 20 GHz Highband Coupler (Option 521 - Standard)
Figure 3-33 A24 20 GHz Highband Coupler (Option 521 - Option 1EM)