“Interesting, any specs on frequency response, s/n ratio of the station?”
Proofs of performance documentation, although no longer required, were never required to be submitted to the FCC and therefore are not in the master 1150 AM Vancouver file in Washington, D.C. They exist only in the local files at the station. Although they might still exist, I doubt it. Also, “high fidelity” meant something totally different back then.
“double wide” ???? Never heard of this. Without a custom made receiver, wider broadcasts with better frequency response would be undetectable. Receiver performance is traditionally the weak link in AM broadcast reception.
Jr, I am sure it was marketing and not engineering. Early AM transmission systems didn’t pass full fidelity signals. With plate modulation, the size of the modulation transformer (and the price) would be untenable if you had full spectrum audio. Better sounding AM didn’t really come along until low level modulation techniques came around, eliminating a high level modulation transformer.