This eBay sale is for ONE (1) Vacuum Tube, aka Valve(UK), Lamp(EEU), Rohre(DE) 

Type type : National Union 12A (UX-4) Triode Tube Made in the USA with Dated Code : "V" etched.
Physical   : Black Phenolic base is etched "z National Union z" "V"
4 Pins       :  UX4 (UX-4) 2 Thick 2 Thin Base with bayonet
Etched Glass : Circle with "12A" "Made in the USA" inside the circle, a little faded but visible.


Condition: Very Lightly Used - Found out of Box, Tested above Vintage Factory Average NOS, 
Calibrated TV7D/U Tested Transconductance(Gm) = 83.1/min good=42, 83.1=2,077.5 uMhos at 12.9 mA Plate Current emissions. This is a very strong tube.

This tube will ship in a new Westinghouse Box as shown with a printed copy of this description and test results.

Please read the pics from the Vintage RCA/Cunningham/Sylvania Data Sheets where they show Average Factory new
Transconductance (Gm ) and Plate Current Emissions in mA depend upon the Plate Supply Voltage Applied to
the tube under Test.
'Bogey' Values for Tube Type 12A for Transconductance(Gm) and mA Plate Current Emissions :
                                             Plate Supply Voltage:
                                            90V        135V      180V (max).
Transconductance( Gm)   1,575      1,650    1,800
Plate Current (mA)             5.0-5.2      6.2       7.6-7.7

All TV7 versions test at a maximum of 150VDC Plate supply Volts and 135VDC Screen/Grid Volts.
This tube was tested at 150VDC Plate Supply Volts.

Our Test Bench: Dan Nelson Recently (07/24/2023) Restored, Upgraded and Calibrated TV7D/U with Digital Meter
reading Gm and mA.

NO Shorts, NO Gas, No Leakage, No Apparent Microphonics detected,

TEST RESULTS:  Gm = 83.1/min good=42, 83.1=2,077.5 uMhos Gm at 12.9 mA Plate Current emissions



Details of Tube Type 12A
Identical to12A = NX112A = CV1774 = NU-12A = P112A = X112A = F12A = 412A = PA112A = 112A = UX112A = CX112A
Similar Tubes
Normally replaceable-slightly different:
  38012 ; PX1120_Tungsram ; WX25
Other base and data slightly different:
  WD25
BaseUX-Base (4 Pins (2 thick, USA 1924, UX) (Codex=Bc)
Was used byRadio/TV-reception etc.
FilamentVf 5 Volts / If 0.25 Ampere / Direct / Battery =
Description

UX112 was having a filament for 0.5 Amps and was designed for battery-operated sets equipped with UX201A tubes. It was replaced in 1927 by the UX112A (112A, 12A, etc.) with the half (If) of 0.25 Amps.