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Bias design, amplifier design, filtering etc.

bob85

Supporting Member
Mar 30, 2005
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interesting link,
it notes the same problem i did regarding constant current bias not having the ability to track modulation of the signal due to the bias circuits very high output impedance,
their answer was to add a current boost pass transistor to make it act like a constant voltage source but that also degrades their circuits ability to track temperature changes in the rf devices,

im interested to see what circuit ken has in mind and how it operates(y)
 

-=PEAKABOO=-

Active Member
Oct 29, 2001
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This has been a very informative thread!!!! I am glad I found this forum. Peakaboo is even on here! This is where he hides from the other forum LOL.

I have been on this forum for years man. I just did not post for about a year or so and I lost my original status:confused:

I wish there was a way to fix that but maybe not.
This forum original started I believe about 10 or so years ago and I was a member from then on. CDX#10 by default.
 

-=PEAKABOO=-

Active Member
Oct 29, 2001
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A recent pic.

IMG_0304.jpg
 

Moleculo

Ham Radio Nerd
Apr 14, 2002
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Peakaboo, what's the transistor configuration on that thing? Have you ever built any thing for 6m that will output somewhere in the neighborhood of 600 watts (or more?)
 

-=PEAKABOO=-

Active Member
Oct 29, 2001
642
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Peakaboo, what's the transistor configuration on that thing? Have you ever built any thing for 6m that will output somewhere in the neighborhood of 600 watts (or more?)

That is just the bias circuit in the picture, it is 6x2SC2879 amplifier.
Yes I am familiar with 6 meter amplifiers, never did anything that did that much power though.
 

bob85

Supporting Member
Mar 30, 2005
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getting your 6pill bias on yo(y)

are you using the three transistors to track heatsink temp?
what is the drift like
how well does base voltage hold up at full drive

yes i am a nosey _ _ _ _ but i aint biased;)
 

-=PEAKABOO=-

Active Member
Oct 29, 2001
642
0
26
getting your 6pill bias on yo(y)

are you using the three transistors to track heatsink temp?
what is the drift like
how well does base voltage hold up at full drive

yes i am a nosey _ _ _ _ but i aint biased;)

Yes, 3 transistors, 1 per stage to track heat.

Very stable at the drive levels I have tested it at.

Drift? I see no drift except for when the heatsink is warming up.
 

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