I have several USN 803 tubes from Catoctin. They are circa WWII and were used as audio modulator tubes in high power AM transmitters. I was wondering if anyone has any experience with these, and if so, how they might work in a high fidelity tube amp application. Plates are capable of handling 200 watts so I could probably get 50 watts of audio in a single ended design without pushing them to hard. Any thoughts?