Secondary tested on a curve tracer, and within spec. 
Reviewer:
Seth Burgin
from PHOENIX, AZ USA
After having a possible error called to my attention, I opened a sealed All Electronics box I brought back from California, and put 10 of these on a Tektronix 576 curve tracer. They withheld at + 18% voltage before the casings cracked. At 150% they popped apart. At 100% they ran hot, totally normal. I put some pinned heatsinks on a matched pair thermally coupled them, tied the clips to some copper foil, and these ran at 135% no problem. This batch came out of the Los Angeles area. I also tried another batch I bought in Colorado, and had similar results. An older batch did not fare as well, but their origins are not 100% traceable. Just for fun I put another pair on a Sony built Tektronix 371B. These will not dissipate 1500 watts, but these are only 1.5 watt thermal energy rated, so I expected them to fly apart. 600mA was fine, and the forward gain is typical for a 2N3904. They do vary, and this is 100% normal. If you need matched pairs or complimentary pairs, buy some equipment and match them yourself. I also checked these on a Leader curve tracer, and used cold spray, and checked the hfe. They may not be the world's best 2N3904, but they are more than adequate and seem better than average. I did have one bad batch of Fairchild labeled 2N3904s, but I can not say IF they came from All Electronics or when. Anything that showed up in the past 24 months seems totally fine. I also ran some on an multiple floating ground vintage Heathkit transistor tester. Leakage was well within spec, as was gain, bias, etc. Test equipment Fish 8840 (China), Heathkit transistor/FET tester Model IT121, Testline Curve Tracer model 101, Curve Tracer Judd Nelson Curve Tracer, B&K Model 501 Curve Tracer, Tektronix model 576 curve tracer and Tektronix model 371B curve tracer. The smaller curve tracers were run into a Tektronix Model 2245 O Scope. hfe was also tested on a Radio Shack model 22-174B, which gives a pinout like the Chinese kit tester. These cheap tester do work, but a curve tracer works better. I also ran these on a Sencor, Triplett, and other transistor testers. Those other testers have not been gone through and calibrated yet, but the results seemed good. The 3904 may be the most common NPN bipolar ever. These also seemed to check for Rohs compliance also but I use lead solder and old components, so it's hard to tell. I don't know very many people who love lead free solder, unless they are fixing Tektronix test gear. Remember pretest all components that are going to be used in critical circuits! Batches vary even in new production! For general use, these are just fine! We try our best to keep parts form different suppliers in separate bags or boxes, but with 2 deaths in the family, and another tech suffering a stroke, I am getting stretched pretty thin lately! 73s KI7AQJ
6 of 7 people found this review helpful.
Do you?
Yes
No
(2 Reviews)
