Matched Pair Philco Type / Number 27 #27 Vacuum Tubes Valves Black Plates 6AF4A engraved base number 78 tubes

engraved base number 78 tubes were tested on our Paul Hart-calibrated TV7/U for shorts

They have chamfered top O getters

but They are more cosmetic than anything else

They measured 38

Tube One measured 47/44 while Tube Two measured 48/43 where minimum (65%) is 25/25 and 100% is 38

Matched Pair Philco Type / Number 27 #27 Vacuum Tubes Valves Black Plates 6AF4A engraved base number 78 tubesThis matched pair of Philco Type 27 triodes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 35 for Tube One and 36 for Tube Two where minimum (65%) is 25 and 100% is 38. The tubes have rounded black plates; wire snubbers for increased rigidity and lowered microphonics; dimpled sheet getters; excellent flashing and well secured bases and bottles that are nice and