6688=E180F National UK gray plate NOS probably made by Amperex (16ma) Title: 6688

6688=E180F National UK gray plate NOS probably made by Amperex

16ma

Gm=14,100

(10,000 hour 9-pin frame grid broadband Pentode, variant is 7737)

– Supratek Chenin, Cortese preamp
– Yamamoto 06-3 2010