You have probably had many answers by now. The BC375 was very unstable. Modulation ended up being a mixture of AM and FM, about 20 kc wide. That's the bad news. The FCC got after a few hams in the US for using them on the air.
Now the good news. AfterWW2 Air France installed thm on Connies for Atlantic runs. They had one good feature. On CW they didn't arc over at high altitudes The ART13 did that they used. I used to work in Maintenance for Lockheed.
73, Van