[Hallicrafters] HT-32B Trans

[Wilson Curtis]

Looking for some clarification.
Page 3 of the Hallicrafters' HT-32B manuel.
Figure 3. Application For Accessory Relay Contacts
The receiver on the left shows the SX-100, SX-101 & SX-115
Center shows the HT-32B  
My question relates to the connection shown between pin 4 on the receiver outlet and pin 7 of the HT-32B outlet. It also shows a 10 K ohm pot connected to the wire between the receiver and transmitter : i.e."RF Gain Set for Desired Level When Monitoring CW Transmission"
What exactly is the purpose of this connection?
Thanks.
Reg Curtis - VE9RWC/KB1WCP...............................................................................................