Description

1963 Vintage 5U4G Full-Wave Rectifier Vacuum Tube See Photos For Test Results! Date Code Determined By The Base Print Or GE Dot-Matrix Etched On The Glass Under "5U4GB" for Pre-1960 and under "U.S.A." after 1960. Read details below to learn how we test our vacuum tubes. Our vacuum tubes are always tested on three, or more, individual testing devices. uTracer3+ (curve tracer and tube tester up to 400 Volts 200mA), uTracer6 (curve tracer and tube tester up to 1000 Volts 1A), (2) EICO 667, TV7/B, Hi c kock 600A, 800A, BK 607 and a host of other test equipment. This allows us to test vacuum tubes in a large variety of ways that are better suited for a particular application. For example, if you want power tubes for a Class AB amplifier, those power tubes / output tubes need to be somewhat matched (% advice varies from person to person) say 10% or better in output at a certain operating point during the amps normal operation. That could be 300-500 Volts. To get the best results for matching, the amp itself is always the best test. T he second best (our personal opinion) process for matching these tubes is a curve tracer which can plot out a graphical representation called a "curve". Each tube in a matched pair can have it's curves traced at certain bias points. The results from each tube can be compared to see how close they are at different operating points. We superimpose the curves in our uTracers software. In addition, curves can then be referenced to the vacuum tube manual (or a data sheet readily available with a google search) to compare * it with the typical curves shown there for a "Bogey Tube" . Curve tracers in themselves, semiconductor (transistor) OR vacuum tube, are design tools for the amp builder and audio / tube amp designer. W e also Class A Test All Audio Tubes For Test Result in our listings unless otherwise specified! This means we use the parameters in RCA Receiving Tube Manual, GE Tube Manual, etc, or from data sheets. *NOTE : Tube manufacturing tolerances were very large, as high as 40%! That means a new tube could read very low and still be considered good (look at any tube tester that has a "Bad Good" scale, and notice how large the "Good" is overall). A "Bogey Tube" is a vacuum tube that matches the Vacuum Tube Manuals numbers are better. Thanks for visiting our store. Click "Save Seller" for more great items! Shipping The item will be packaged in original box (if applicable) and then sent out in a seperate shipping box. We use USPS or FedEX shipping services. Please contact us for special shipping needs. Please ask any questions or concerns you have prior to purchasing so your transaction can be fast and accurate!