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@vacuumtubes.com>
To: TenTec@contesting.com
Cc: TenTec@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@vacuumtubes.com
636-939-9190
SND Tube Sales
105 N. Division St.
Bonne Terre, MO 63628
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