Rare NOS 1972 TELEFUNKEN ef86 silver MEDICAL grade SUPER STRONG tube preamp limiter tube mic U67

Here for sale a super rare, super strong and quite special Telefunken ef86 made in Germany at the Ulm factory in 1972 the 24th of septembre.
It has obvious remaining trace of the red tip marking for medical and lab grade

Test result 116 %    

Code U4202904

It has the distinctive Telefunken diamond mark molded on the bottom between pins.

It's like new, after a full check, it had just had a few hours of use, tests and auditioning .
In top condition, even all the super fragile white label and factory code are almost perfect.

Silver shield, ring getter, a very high quality tube wich is super rare now in this perfect condition in medical, lab, red tip version.

Highly thought after by audiophiles, pro audio studios and guitar player. THE Telefunken sound...

And this tube benefit sfrom excellent resuts also when lower voltage is applied on heater wich means very robust cathode and super strong life test results !
  No short
 No leaks  no issue                      
I COMBINE SHIPPING ,Test result 112 %   Code U4202904

 SO PLEASE HAVE A LOOK AT MY OTHER INTEMS AND SAVE .

Shipping price includes tracking and insurance.

  Fully tested onJackson 648S for

Filament

Circuit

Shorts

Plate

Life test...

The Jackson 648. It is definitely one of my favorite tube testers. While it does not employ a mutual conductance test circuit, it does use an advanced emission circuit that applies separate element voltages to each tube element, and separate load circuits are also used. “These voltages and loads have been carefully selected for each tube to meet most ideally the normal operating condition of the tube.” (Source: 1950 Jackson catalog.)

In my experience, the Jackson circuitry is very effective, and often will surprise you with accuracy that approaches Hickok’s coveted “mutual conductance” test method. ( Source tubesound web site.)

I do my best to test and describe the tubes the best I can.

Note that test results may vary from one tester to an other so this must be taken as an indication, although my jackson is regulary tested for calibration.

 Photos are part of the description you get what you see.

Private sale so no guarantee or return please.

But if any problem (never happened yet ) please contact me first.

Thank you for your interest.