[TenTec] Centurion 422b troubleshooting help needed

[Duane Calvin]

Mine was an early life failure - as I mentioned, within the first hour or so
of operation.  After replacement, it lasted several years until I sold the
amp.  I don't recall the replacement device - TT shipped it out to me
immediately.  I do remember what a tough soldering job it was to remove that
board to work on it with the heavy filament wires.  If you socket the
transistor, be sure the socket and XSTR connections can handle the current.

	73, Duane

Duane Calvin, AC5AA
Austin, Texas
ac5aa at ac5aa.com 


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of A R
Sent: Sunday, February 21, 2016 9:49 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Centurion 422b troubleshooting help needed

   
Duane, Andy, and Carter:

 

Wow. Just confirmed that the TO-3 bias transistor (MJ15001) in my 422b is
shorted collector-to-emitter. Admittedly, 4 failures isn't a huge sample,
but it sure suggests that there's either a quality problem with the
MJ15001's, or the circuit (application) is overstressing their spec'd
characteristics/limits. Did you all re[place the faied transistors with
MJ15001's, or some other transistor? My 422 manual calls out a 2N3055, which
is a "15A, 60V, 115W" device, compared with the MJ15001's "20A, 140V, 250W"
rating. Without knowing the root cause of Q1 failures, I'm tempted to
"socketize" Q1. At least replacing Q1 again (if needed) wouldn't be quite
the PITA (and board-stressing) as it is with a soldered-in Q1. How much
failure-free time on your amps since replacement of Q1? Thanks for the
feedback and good info!

73,

Allen--W7GIF


----- Original Message ----- 

From: Duane Calvin<mailto:ac5aa1 at gmail.com> 

To: 'Discussion of Ten-Tec Equipment'<mailto:tentec at contesting.com> 

Sent: Sunday, February 21, 2016 6:14 PM

Subject: Re: [TenTec] Centurion 422b troubleshooting help needed



Bias transistor?  I had one go out on my Centurion when it was only a couple
hours old.

73, Duane

Duane Calvin, AC5AA
Austin, Texas
ac5aa at ac5aa.com<mailto:ac5aa at ac5aa.com> 



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