Engineer-in-Charge George Greaves trains another engineer on the Master Control panel at Radio City.

The operator here determined which studio program was fed to which broadcast phone line on the network. Fourteen different circuits could be fed simultaneously, judging by the number of VU meters along the top. All programs fed to KPO, KGO and the two networks originated here. The extensive audio patch panels on either side could be used to quickly substitute a failed studio amplifier in case of emergency. The telegraph sounder on the desk was used to communicate with the KPO transmitter in Belmont.