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[Amps] RF power transistor curve trace question

To: Amps <Amps@contesting.com>
Subject: [Amps] RF power transistor curve trace question
From: Dan Sawyer <dansawyer@earthlink.net>
Reply-to: dansawyer@earthlink.net
Date: Sat, 13 Jun 2009 20:07:09 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
All, this is a continuing question in the quest to understand and modify 
an ENI base bipolar power amp. I speculated the power transistors were 
SD1728's however I am not so sure. I have one SD1728 from another app. 
When placed in the curve tracer it produces a pattern with almost 
horizontal trace, based step. I removed the devices from one of the ENI 
boards and checked the curves . They were rising with a pattern of 
between 0 and about 15 degrees, significantly different pattern. (the 
gain was close.)

What determines the 'slope' in an RF power transistor?

What is its significance?

These are marked as ST devices, however they appear to have local 
markings. They are definitely in a .55 inch case. Any speculation on the 
device?

Does the different slope on the curve tracer identify the devices as 
different? What spec affects the slope?

Thanks in advance - Dan
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