I’m taking a chance here, but I think this was taken before the fire that severely damaged the WKPT studios. I don’t recognize the studio configuration or that strange wall treatment.
I didn’t have any luck tracking down when Pilgrims Songs sheet music was published, but the microphone is a Western Electric 639 or so, made in the late 1930s (after 1941, it would have been branded as an Altec). This mike, or one like it, was still around when I was at WKPT. People had their preferences as to the setting. I liked cardioid and got fussed at one time for switching it. Today, these mikes are selling for around $600 to $800 on ebay.
There is nothing of interest on the back of this card…no publisher, no photographer attribution. Annoying.