I think the 'Squadron Signal' picture book on the PBY aircraft shows the ATB at radio position.

One of the two ATBs i have owned came from Frederick Chesson, who had been a PBY pilot. I should have interviewed ( grilled ) him ! The other ATB came from G&G NYC, maybe the last one sold. I still have the Chesson one, need to find the keying relay for it, which was removed. I think i still have one 'metering kit' for it. This pretty nice equipment....but i have 4 or 5 Japanese HF sets which might be even more big fun to use, and the clock is always running.