10 x 12ax7 Sylvania Tubes
Made in USA for Baldwin
Long Ribbed Grey plates
The lettering is smudged/missing
Tested on Hickok 6000A
1320/1300
1400/1320
1350/1340
1460/1330
1320/1500
1390/1320
1770/1740
1520/1580
1290/1500
1520/1490
Mutual conductance(100%) = 1250/1250
I do combine S&H when possible