[TenTec] Centurion 422b troubleshooting help needed

[A R]

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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