Tubes are identically the same, construction wise. One logo RCA and other logo Sylvania! One tube broken key guide!
Triple getters, welded plates, three holes in plate, brown base!
One of the best sounding 6550 tubes!!!
Tested on RoeTest V10 (the best modern tube tester!)
Tube 1: 76mA 8.62mA/V
Tube 2: 82mA 8.75mA/V
87mA 9mA/V = 100% (Va 400V, Vg1 -16.5, Vg2 225V)
PRICE IS FOR TWO TUBES (ONE PAIR).
I will pack and secure tubes good.
Feel free to contact me.