Rare 1957 Sylvania 5Y3 GT 5Y3GT BLACK BOX PLATE, balanced and super STRONG.

Here for sale a rare earlySylvania 5Y3Gt black box plate, rectangular getter, copper getter post, black base.
. Getter flash shows some use but still nice, obviously a used tube but an healthy one, perfectly balanced and still super strong.
 Made in 1957 in the USA,  by Sylvania.

Tests results   114 %   112 %

A great rectifier tube

Fully tested on Jackson 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.