EL34 Philips Xf1 / Laboratory samples D-D getter 1957 v30 v36

Description

Here is a pair of Philips Miniwatt EL34 early production tubes. The pair is a selected for the Philips Physical laboratory NAT LAB; which used the highest grade tubes only;  see pictures and test data.

The Philips Sittard production Double D-getter is, apart from the metal base EL34, considered as the absolutely best sounding EL34 ever. 

The pair has excellent specs. Both tubes have date code Xf1 X7F. 

The measurement data below show that the pair is matched. And fully in line with the Philips specification for an EL34.

Test results*

The measurement data below show that both tubes are matched. 

Valve 1 V30	Ia (plate current): Transconductance (Gm): Gas test, Shorts test:	96 mA           11,9  mA/V OK	=  NOS = NOS
Valve 2 V36	Ia (plate current): Transconductance (Gm): Gas test, Shorts test:	102 mA       12,2  mA/V OK	= NOS = NOS

Telefunken measuring values for new unused tubes:

• The rated emission value for a new EL34 is:  100 mA. 
• The rated transconductance value for a new EL34 is:  11 mA/V . 

For Telefunken specs info see last picture 

Test condition & equipment:

Mutual transconductance, plate current, gas and shorts test equipment: AVO Mk IV (Dutch army tester) , AVO Valve Data Manual 23rd edition 1981, RFT stabilised mains, Utracer3+, Philips PE 4832, 2x Korad KA3005P programmable power supply, 2x Keithley 2700 and 2x Fluke 145. 

Test conditions: Ua (plate voltage) = 250 Volts, Us (screen voltage) = 265 Volts, Ug = -13,5 Volts and Uf = 6,3 V ± 3% (factory conditions). Please read our test page.

 

Summarized description