EL34 RFT strong pair V63 v65

Description

Here is a pair of RFT EL34 old production valves. 

The EL34 is a transmitting beam tetrode. The tubes have a top halo-getter. The RFT old production is absolutely the among the best of EL34. Many Telefunken EL34 tubes actually are produced by RFT ! These tubes deliver superior sonics compared to the Chinese and Russian new production EL34.  

The pair has STRONG test values. 

Test method

Mutual transconductance, plate current, gas and shorts tested with: AVO CT-160 (Dutch army tester), Utracer3+, AVO Valve Data Manual 23rd edition 1981, Philips 1532, RFT stabilised power supply and 2x Keithley 2700. Test conditions: Anode 250V, Screen 250V, Grid -13.5V, Filament 6,3V. Before testing they were burned in for 48 hours. Rated Ia = 75mA, Gm = 11 mA/V (for in practice NOS tubes often between 10 & 11 mA/V). AVO Valve Data Manual 23rd edition 1981.

Test results*

The measurement data below show that the pair is nicely matched. 

Valve  V65

Ia (plate current): Transconductance (Gm): Gas test, Shorts test:

92 mA       10,3  mA/V OK

=  NOS =  Strong

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