[TenTec] Centurion Bias Transistor Follow on post

[Lee]

Hi Mike,

You are probably doing this but I will ask just to be sure.  Are you 
using the BASE as the common test point and testing EMITTER and 
COLLECTOR to base.  In a NPN transistor the BASE - EMITTER junction is 
one diode where the BASE is the anode and EMITTER the cathode.  The BASE 
- COLLECTOR junction is the other diode where the BASE is the anode and 
COLLECTOR  the cathode.  Testing the EMITTER - COLLECTOR leads will show 
open in both directions when the BASE is open.

73,

-Lee-
WA3FIY

------ Original Message ------
From: "Michael Marx" <sndtubes at vacuumtubes.com>
To: TenTec at contesting.com
Cc: TenTec at yahoogroups.com
Sent: 11/20/2017 1:09:53 PM
Subject: [TenTec] Centurion Bias Transistor Follow on post

>Guys,
>
>I just posted a message about my Centurion with a bias problem.  As I 
>stated I replaced the bias transistor which did not fix the problem.  
>Here is something interesting that I don’t understand.  I bought 5 of 
>them from Mouser.  When I measure the transistor junctions with my 
>Fluke 87 meter in the diode function, one junction seems normal as it 
>measures .5 V in one direction and open in the other.  Normal, right? 
>Now the other junction measures open in both directions.  It also 
>measures open in ohmmeter mode.  Could I have bought 5 bad transistors? 
>  Is that even possible?  What am I doing wrong in testing these 
>transistors?  They are just an NPN bipolar transistor, right?  FYI it 
>is an MJ15001G by ON.  This is exactly what Ten Tec sent a few years 
>ago when I had to replace the transistor.
>
>Very confused.
>
>73
>Mike WB0SND
>
>
>Michael Marx
>sndtubes at vacuumtubes.com
>636-939-9190
>
>SND Tube Sales
>105 N. Division St.
>Bonne Terre, MO  63628
>
>
>
>
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