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[Amps] matching power transistors.

To: Amps <Amps@contesting.com>
Subject: [Amps] matching power transistors.
From: dan <dansawyer@earthlink.net>
Date: Tue, 24 Dec 2013 05:43:42 -0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Good day all. I am building an rf power amp from th430 / sd1728s. I have 6 devices and am looking for the best matched set. I also have a Tek curve tracer. I have set the tracer bias to produce the first trace at the 1 cm line and steps to 5. The best matched pair is:

1. Bias value:    first trace T1 .8 cm and T2 1 cm
2. hfa value:    5th trace T1 5.6 cm and T2 5.5 cm

My questions are:

1. Is the bias value important to matching. Since the value is small, if the difference is small is it swamped in normal operation? 2. The relative amplification is critical to matching. Does this value scale from small signal inputs to operational level inputs?
Is testing at larger base step values required to match?

Thanks,

Dan kb0qil
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